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458 Cards in this Set
- Front
- Back
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Describe the cortex of the ovary. Where are the ovarian follicles? |
It is the peripheral, outer region. Ovarian follicles are within a cellular CT stroma |
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Describe the medulla of the ovary. |
It is the central region. CT stroma containing main blood and lymphatic vessels and nerves. |
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Describe the germinal epithelium of the ovary - include the cells |
Covering epithelium of the ovary. The cells look cuboidal |
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What is external to the follicular cells? |
Basal Lamina |
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What are the components of the ovarian follicles? |
Oocyte, surrounding follicular cells and basal lamina separating follicular cells from CT stroma |
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What happens to the CT as the follicle grows? |
Some of it will develop into distinct layers called thecal layers |
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What are the types of Ovarian Follicles? |
Primordial, Growing and Mature/Graafian/Preovulatory |
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Describe the Primordial Follicle |
Inactive, resting follicle. It has a store of oocytes and surrounding coverings. Consists of single layer of flattened follicular cells surrounding primary oocyte |
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Describe the Growing follicle |
It is the follicle once it is activated. Can be subdivided into primary/secondary or pre-antral/antral categories |
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What does the Follicular Development involve? |
Ooocyte and follicular growth. Cell division and cellular differentiation |
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Where does follicular development culminate in? |
Ovulation |
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Do all follicles and their oocytes complete development? |
No, most undergo atresia |
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What makes up the wall of the follicle? |
Granulosa cells |
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What do follicle cells undergo and develop? |
Undergo large amount of division and then differentiation occurs. Develop particular receptors for LH and FSH |
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Does the early growth of follicles depend on gonadotrophin stimulation? |
No - they are independent of it (therefore don't depend on LH or FSH |
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In the growing follicle, what leads to multi-layered follicular wall? |
Mitosis of follicular/granulosa cells |
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How does a growing follicle change in shape? |
From flattened to cuboidal |
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When does the Zona Pellucida begin to form? and between what? |
Growing Follicle and between oocyte and granulosa cells |
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What develops during the growing follicle stage? |
Theca Interna and Theca Externa from Stroma |
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What does the theca interna develop from? What does it acquire? |
Surrounding CT cells and acquires receptors for LH |
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What are the paracrine factors for follicule growth? |
Growth factors and calcium ions |
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The continuation of growth is dependent on what? |
Pituitary hormones - FSH and LH |
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What does the binding of LH and FSH stimulate? |
Conversion of cholesterol |
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What continues to occur during mature graafian follicles? |
Continued differentiation of granulosa cells into subpopulations |
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What are the subpopulations of granulosa cells? |
Outer wall, corona radiata and cumulus oophorus |
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Describe the outer wall granulosa cells - what do they contribute to? What do they secrete? |
Contribute to follicular fluid. Secrete oestrodial under influence of FSH. Basement membrane is attached to it |
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Describe the corona radiata |
it surrounds oocyte and zona pellucida and is a protecting layer of cells |
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Describe the oophorus |
It is the connecting stalk and therefore connects the oocyte to follicular wall |
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Is the Mature Graafian Follicle well defined? |
Yes - theca interna is vascularised and has steroid producing cells. Theca externa is also well defined |
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What is follicular atresia? |
Degeneration of follicle and/or oocyte prior to ovulation |
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Why do we think atresia occurs? |
Because there isn't enough gonadotrophin |
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Can atresia occur at any stage of follicular growth? |
yes |
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Do the granulosa cells die too? |
Yes |
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What else may contribute to atresia and arrest of the follicle? |
Lack of hormonal support |
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What occurs as a result of the LH surge? |
Ovulation |
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Why is the LH surge possible? |
Because positive feedback of oestrogen occurs which increases amount of LH due to granulosa cells having LH and FSH receptors |
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What happens to the oocyte during ovulation? |
Completes first meiotic division |
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What causes the actual release of the secondary oocyte? |
Hormonally mediated changes and enzymatic effects |
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What are the hormone mediated changes in the release of the secondary oocyte? |
Increase in volume and pressure of fluid in antrum therefore oocyte is released out of cavity |
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Where can the secondary oocyte be picked up after release? |
Fibriae - finger like projections on oviduct |
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When does ovulation culminate? |
In the release of the secondary oocyte, the surrounding zona pellucida, the coronal radiata and cumulus cells and the antral fluid |
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What does the remaining collapsed follicle form? |
Corpus Luteum |
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What appearance does the Corpus Luteum have? Why is this? |
Endocrine organ because there is a production of progesterone and oestrogen |
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What infiltrates the corpus luteum and what does this mean for the granulosa cells? |
Blood capillaries from the Theca Internat. It means that the granulosa cells are now known as granulosa lutein and theca lutein |
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What happens if there is no fertilisation? |
Regression after 14 days |
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What is the Corpus Albicans? |
Scar tissues left over from functional corpus luteum |
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What happens after the degeneration of the corpus luteum? |
Remanents of granulosa and theca lutein cells are phagocytosed by macrophages |
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Why is scar tissue apparent after the corpus luteum degenerates? |
Because there is an infiltration of fibroblasts which lay down collagen and hyalinisation occurs in the region, thus producing white CT scar tissue on ovary |
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What is the average ovarian cycle? |
28 days |
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What classifies as the ovarian cycle? |
interval between successive ovulations |
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Describe the follicular phase of the ovarian cycle in terms of FSH levels, how long it goes for, and which hormone is most dominant |
FSH levels do not equal LH levels because growing follicles produce inhibin which has a negative feedback to down regulate production of FSH. The length of the follicular phase is 10-14 days and Oestrogen is most dominant |
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How long does the Luteal phase go for? |
12-15 days |
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Which hormone is most dominant during the Luteal phase? |
Progesterone from corpus luteum |
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What type of hormonal control is there for ovarian functions? |
Negative and positive feedback |
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What does the release of GnRH from the hypothalamus act on in the follicular phase of the ovarian cycle? |
The anterior pituitary to bring secretion of LH and FSH |
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What does FSH influence in the follicular phase of the ovarian cycle? |
Granulosa cells converting to androgens (testosterone) to oestrogen |
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What effect does low oestrogen have on the hormonal control of the ovarian cycle? |
Negative feedback on the hypothalamic axis |
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What effect does high oestrogen have on the hormonal control of the ovarian cycle? |
positive feedback which increases LH therefore granulosa cells can develop receptors for LH |
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What effect does LH have on the corpus luteum? |
bring about secretion of progesterone and oestrogen late in cycle, and has negative feedback |
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What is the role of the Uterus? |
Provide suitable physical and hormonal environment for implantation and support/maintenance of embryonic and foetal development during pregnancy |
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What role does the Uterine Cervix have? |
Retains foetus in uterus |
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What does Cervical Mucus do? |
Facilitates sperm transport to site of fertilisation and prevents entry of Micro-organisms to uterus |
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What are the 3 parts of the anatomy of the uterus? |
Body, Fundus and Cervis |
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What are the 3 layers of the uterine wall? |
Perimetrium, myometrium, endometrium |
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Describe the perimetrium |
It is the external serosa layer of the uterine wall and has CT covered by mesothelium. |
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Describe the myometrium |
Middle muscular layer of uterine wall, and is also the thickest layer. It has smooth muscle running in all directions |
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Which layer produces contractions during labour? |
Myometrium |
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Describe the endometrium |
It is the inner most layer. Mucosa of uterus. Has simple columnar epithelium over lamina propria containing tubular uterine glands |
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What are the two endometrial layers? |
Stratum functionalis and Stratum basale |
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When is the Stratum Functionalis shed and re-built? |
Shed during menstrual phase of each cycle and re-built afterwards |
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Describe the stratum basale |
Basal layer, compact and always present |
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Is the stratum basale retained during menstruation? Why, why not? |
Yes because it is reserve tissue for regeneration of stratum functionalis in subsequent cycles |
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Where does the Uterine blood supply come from? |
Outside uterine wall and penetrates uterus |
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Describe the uterine artery |
Gives off number of branches |
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Where does the uterine artery penetrate the uterus? |
At the myometrium |
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Is there only one uterine artery? |
No, there are more arteries called radical arteries. These extend into basal part of endometrium (the stratum basale) |
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What do straight uterine arteries do? |
Supply stratum basale |
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What do spiral uterine arteries do? |
Continue into more superficial stratum functionalis |
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Do spiral uterine arteries continue into anything else? |
Yes, into spiral arterioles |
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What do hormonal changes cause in the endometrial vessels? |
Spinal artery vasoconstriction and therefore necrosis of the stratum functionalis and menstrual flow |
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When do these hormonal changes in the endometrial vessels occur? |
At beginning of menstrual phase |
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What changes does the Endometrium undergo in response to hormonal changes? |
Cyclical changes in appearance |
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What do the changes of the endometrium appearance correlate with? |
Maturation of ovarian follicles |
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What is the Menstrual cycle? |
Series of events to describe the appearance of tissue in the uterus |
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When does the menstrual cycle begin? |
Puberty |
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When does the menstrual cycle cease? |
Menopause 45 to 55yrs old |
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What is amenorrhea? |
Lack of normal cyclic activity |
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What is the average length of the menstrual cycle? |
28 days |
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What are the 3 phases of the Menstrual cycle? |
Menstrual, proliferative and secretory |
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What does the organisation of tissues in the menstrual phase look like? |
Disrupted and vessels rupture |
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What occurs to the epithelial covering during the menstrual phase? |
Breaks down |
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Why does the breakdown of the epithelial lining occur during the menstrual phase? |
Because there is a massive decrease in oestrogen and progesterone from ovary therefore a local hormone is released |
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What does the local hormone released from the ovary do? |
Has very strong binding to muscle and so it binds to smooth muscle of arterioles |
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What blocks the spiral arterioles flow to the stratum functionalis? |
Contraction of muscle |
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What happens to the stratum functionalis during the menstrual phase? |
Becomes necrotic |
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What is the result of the menstrual phase of the menstrual cycle? |
Menstrual flow (tissue, blood, uterine fluid) |
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What is proliferative phase also known as? |
Follicular phase |
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What occurs to the tissue during the proliferative phase? |
Breaks down and the degeneration of the corpus luteum |
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What does the proliferative phase correspond to? |
The follicular phase in the ovary when antral follicles mature |
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What is the result of not much oestrogen and progesterone being produced during the proliferative phase? |
Inhibition of LH and FSH |
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How does Oestrogen get into the blood during the proliferative phase? Where does it bind to? |
Through uterine artery and binds to target cells in remaining endometrial tissue (the stratum basale) |
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What does the binding of oestrogen in the stratum basale stimulate? |
Mitosis of the stratum functionalis and the repairment of epithelial, endothelial and stromal cells |
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What do the stromal cells secrete? |
Collage and AGS |
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What else is repaired/grows when oestrogen binds to stratum basale? |
Regeneration and elongation of arterioles as well as growth of glands |
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Describe the appearance of the proliferative phase |
Glands are very tubule and mitotic figures present. It all looks very cellular |
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What does the secretory phase link up with? |
The luteal phase of the ovarian cycle |
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What occurs during the secretory phase? |
Maturation and secretion of uterine glands |
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What happens to the levels of progesterone during the secretory phase? |
They increase and therefore maturation occurs and the size of cells increase |
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What sort of appearance do cells in the secretory phase develop? |
Bulging into lumen |
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What appearance do arterioles in the secretory phase develop? |
Convolution and coiling |
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What happens to the CT in the secretory phase? |
They become active and fluid build up occurs because of the convolution of arterioles |
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What appearance do glands take in the secretory phase? |
Look irregular |
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What regulates hormones during the menstrual cycle? |
Ovary |
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What happens to the endometrium if implantation occurs? |
Undergoes decidualisation and is non-cyclical |
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What do CT fibroblasts (aka stromal cells) turn into during pregnancy? |
Polyhedral cells with characteristics of protein-secretory cells (decidual cells) |
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What happens to the appearance of glands during pregnancy? |
They enlarge and become more coiled |
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Describe the features of the uterine cervix |
More rigid, less contractile than rest of Uterus and few smooth muscles, rather more dense CT |
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What is the epithelial lining of the endometrium? |
Mucous secreting columnar epithelium |
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What do the stroma contain in the uterine cervix? |
Large, branched glands that secrete mucous into cervical canal and serve as a plug except around ovulation |
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Are there spiral arteries in the endometrium? |
No |
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Is the endometrium shed during the menstrual phase? |
No |
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What is spermiogenesis? |
Development of the species specific morphology of a mature spermatozoon from stem spermatogonium |
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What does spermiogenesis arise from? |
Meiotic division and spermatids |
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Where does spermiogenesis occur? |
In semintubule compartment of the testes |
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What are the 4 events in spermiogenesis? |
Formation of acrosomal vesicle and acrosome cap; Nuclear shaping; Manchette; Formation of sperm tail |
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What is the acrosomal vesicle derived from? |
Golgi complex and the vesicle migrates from the golgi to cytoplasm |
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What is the role of the acrosomal vesicle/acrosome cap? |
Penetration of egg coats |
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What is contained in the acrosomal vesicle? |
Bag of enzymes that will assist in penetrating the egg |
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What shape does the nucleus go to in spermiogenesis? What happens to the chromatin? |
Spherical to elongated. Chromatin condense |
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What happens to the DNA in spermiogenesis? |
Winds around nuclear proteins |
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What are histones replaced with in spermiogenesis? |
Protamine which has low molecular weight therefore enabling DNA to wind more tightly around protein |
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What is the manchette formed from? |
Region called anualest which has microtubules coming off of it |
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What does the manchette contribute to? |
Shaping of nucleus |
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What does the axoneme of the sperm tail arise from? |
Longitudinal centriole |
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How is the sperm tail midpiece formed? |
Mitochondria aligning around proximal axoneme |
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What are the two key features in a mature spermatozoon? |
Head and Tail |
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What two things are part of the sperm head? |
Nucleus and Acrosome |
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What is the role of the nucleus in the sperm head? |
Stabilises DNA and has implantation foss where the tail attaches to the headW |
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What are the two segments of the acrosome part of the sperm head? |
Main segment and equatorial segment |
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What does the main segment of the acrosome do? |
Covers apical portion of nucleus |
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What does the equatorial segment cover? |
Sperm egg fusion site |
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Does the acrosome extend over the entire nucleus? Why is this answer important? |
No it doesn't. This is important because it is uncovered when fertilisation occurs |
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What is the core of the sperm tail made up of? |
Aconeme |
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Where do morphologically mature sperms go to? |
Rete Testis |
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What are the three sections of the sperm tail? |
Tail midpiece, tail principle piece and tail end piece |
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Briefly descrie each part of the sperm tail |
Midpiece has mitochondria with outer dense fibres, principle piece has fibrous sheath and axoneme;End piece has axoneme only covered by plasma membrane |
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What does the axoneme provide? |
Sperm movement to deliver DNA to site of fertilisation |
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What does the epididymal maturation of spermatozoon involve? |
Elimination of cytoplasmic droplet |
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What does the development of motility involve? |
Lining cell secreting proteins which are incorporated in sperm |
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Can oogonia under division before puberty? |
No |
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When does oocyte maturation occur before ovulation? |
Between period of time where follicular is activated and starts to grow, and the time of completion of the first meiotic division |
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When is the germinal vesicle oocyte arrested? |
Prophase of meiosis 1 |
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What happens when germinal vesicle is activated again? |
You get alignment to form metaphase plate and extrusion of completion of first meiotic division and first polary body |
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What happens to the cytoplasm during the reactivation of the germinal vesicle? |
It is retained by cell that will form ovum |
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What can the granulosa cells of corona radiata do? |
Directly communicate with oocyte and penetrate through spaces in Zona |
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What happens when the germinal vesicle breaks down? |
Redistribution of organelles |
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What do the cortical granules do when the redistribution of organelles in the oocyte occurs? |
Align themselves to form a layer beneath the membrane of the oocyte |
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What happens if you have the fertilisation of the secondary oocyte in terms of the chromosomes? |
They allign at the metaphase 2 |
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What do the cortical granules do if the secondary oocyte is fertilised? |
Released between oolema and zona pellucida and exocytose contents into perivitelline space |
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When is meiosis one completed? |
Prior to ovulation |
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What does the LH surge bring about in terms of the wall of the oocyte? |
It weakens it |
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What is released from the follicle in ovulation? |
Zona pellucida, secondary oocyte, first polar body, corona cells |
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What pushes the zona pellucida, secondary oocyte, first polar body and corona cells out of the follicle? Where do these components go? |
High pressure of fluid . Go to pericaneal cavity where they are picked up by fibrae on oviduct |
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What does the remnants of the follicle wall become? |
The Corpus luteum |
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What does a mature oocyte contain? |
Cumulus (zona pellucida and granulosa cells), polar body 1, ooplasm and zona pellucida cells of corona radiata |
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What is oogenesis? |
Maturation of an ovum from an oogonium |
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Is the number of potential oocytes fixed or can it grown? |
No it is fixed and finite (limited) |
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The growth of the oocyte is completed when? |
Prior to first meiotic division |
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What happens to the first polar body when the oocyte is mature? |
It degenerates |
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What happens to the chromosomes of a mature oocyte? When do they reactivate? |
They become suspended on metaphase plate of meiosis 2 and is only reactivated if sperm-oolemma binding and fusion occurs |
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What must sperm makes it way through to reach and bind with zona pellucida? |
Cumulus cells |
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Why is sperm carried in tubular fluid after leaving the testis? |
Because they are immotile |
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What is the pathway that sperm travel before being ejaculated? |
Seminerfous tubules -> Rete Testis -> flushed to Ductuli efferentes -> epididymus -> vas deferens -> sperm added to accessory gland secretions -> urethra at ejaculation |
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When is fluid absorbed during the transport of sperm? What does this mean for the concentration of sperm? |
During epididymal transit. It increases |
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What happens to the sperm residual body? |
It is phagocytosed |
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What is the transport of sperm assisted by? |
Muscular contractions, particularly of vas deferens at ejaculation |
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What is semen? |
Sperm + fluid vehicle from gland secretions |
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What happens to the plasma membrane properties of sperm during the epididymal passage? |
There is an acquisition of sperm motility and stabilisation of sperm to prevent premature activation. Also can then recognise female gamete |
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Where is sperm stored? |
Distal part of epididymus known as Cauda epididymus |
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What is the contraction of the smooth muscle wall that ejaculates sperm triggered by? |
ANS activation |
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Where does semen pass through once deposited in vagina? |
cervical canal into uterus |
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Why is the cervical canal difficult to pass through? |
It is very narrow, has hostile environment and is acidic, has cervical mucous which can be thick |
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After the cervical canal, where does the sperm travel? |
Through uterotubual junction (UTJ) which has 2 tubes leading to oviduct |
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Do both tubes leading to the oviduct have a fertilised egg? |
No, only one does |
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What other complications might the sperm face once entering the uterus? |
Immune attack from leukocytes and inflammatory response. |
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What occurs at the UTJ? |
Selection of sperm based on swimming behaviour, sperm morphology and sperm surface markers and recognition molecules |
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How long do sperm remain viable in the female tract? |
5 Days |
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Where do sperm live in the female tract? |
The isthmus (closest to uterus) of oviduct |
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Where is the secondary oocyte ovulated into? |
Peritoneal cavity |
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What is the oocyte picked up by? |
Fibria on infundibulum of oviduct |
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Why can the oocyte move through the oviduct? |
Because of the beating of cilia |
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Where does fertilisation occur? |
In ampulla of oviduct |
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What is the process essential for sperm to be able to fertilise an egg called? |
Capacitation |
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What does Capacitation involve in terms of the modification of sperm membranes? |
Reversal of stabilising factors from male tract and increased fluidity to enable acrosome reaction |
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Which events are reversed in capacitation? |
Events that prevented both sperm damage during transit and premature sperm activation |
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What does capacitation involve in terms of hyperactivation? |
Tail can beat quickly and swimming ability for sperm increases. |
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Why is hyperactivation of the tail and increased swimming ability of the sperm important? |
Enables sperm to penetrate the cumulus surrounding the oocyte and the zona pellucida after the acrosome reaction |
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Why does the sperm undergo the acrosome reaction? |
It is in response to agonists |
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Where do all the changes for the sperm occur? |
At molecular level |
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What does the change in lipid order of the plasma membrane for the sperm enable? |
Membrane can fuse with acrosome membraneW |
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Apart from hyperactivity, what is another event that occurs during capacitation that involves the modification of sperm membranes? |
The exposure of receptors for binding with zona pellucida |
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What is the first step of sperm penetration of the egg coat? |
Penetration of extracellular matrix around cumulus cells by hyperactivity of sperm |
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What induces the acrosome reaction? |
Binding to zona pellucida thus changes in membrane |
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What is the cumulus penetration assisted by apart from hyperactivity? |
The cumulus matrix which is susceptible to be broken down by enzyme called hyaluronidase which sperm is rich in W |
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Where is the enzyme hyaluronidase kept? |
In the acrosome and then it digests the matrix |
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What are the earliest capacitated sperm thought to be? |
Sacrificial because they release their enzymes prematurely to help other sperm penetrate the cumulus mass |
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How does sperm-zona binding occur? |
Receptors on acrosome attaching to ZP3 protein W |
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Why can't the sacrificial sperm fertilise the egg? |
Because they won't have the receptors for ZP3 protein therefore won't be able to induce acrosome reaction |
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What occurs during the acrosome reaction? |
Exocytosis of acrosomal enzymes including hyaluronidase, beta-hexosaminidase which prevents further sperm binding to egg and acrosin which digests path through zona pellucida |
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Why are only capacitated, acrosome reacted sperm capable of sperm-oocyte binding and fusion? |
Because it needs the features to penetrate and lose its acrosome so that the binding sites are uncovered and available to the oocyte |
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Where does the sperm-egg fusion occur? |
Between plasma membrane of sperm head overlying equatorial and post acrosomal region and oolemma |
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What happens to the apical tip of the sperm head once fusion occurs? |
It is phagocytosed and sperm is incorporated into ooplasm |
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When does oocyte activation occur? |
Once sperm fuses with it |
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What happens when the sperm fuses with the oocyte, in terms of the oocyte? |
There is a large increase in free intracellular calcium ion levels and these accumulate within the cytosole |
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Why does calcium accumulate in the cytosole? |
Because it is critical for all subsequent events in fertilisation |
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What effect does calcium influx have on the oolemma? |
It depolarises it and blocks further sperm-oocyte binding and fusion |
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What is the cortical granule reaction? |
Exocytosis of enzymes that act on zona pellucida to cause zona hardening and loss of ZP3 binding ability |
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What is the easy way to tell if an egg has been fertilised? |
There will be a second polar body |
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Why is the oocyte depolarised and why is the zona hardened? |
To block polyspermy |
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Which is faster: the depolarisation of the oocyte and the calcium inflow to the oocyte and the cortical granule reaction? |
Depolarisation |
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What does calcium activate in terms of meiosis? |
It activates the secondary oocyte to complete meiosis |
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What happens to the male and female chromosomes now that the egg and sperm has fused? |
They decondensed to form male and female pronuclei |
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What is syngamy? |
the merging and mixing of male and females DNA resulting in 46 chromosomes |
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What is a fertilised egg called? |
Zygote |
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What is the structure of a fertilised oocyte? |
visible second polar body, presence of 2 rounded pronuclei |
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What is a monula? |
Ball of cells |
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What is a blastocyst? |
Organised and polar cells |
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What is a Bilaminar? |
Hatched, differentiation of blastocyst |
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What occurs during days 1 to 3 of fertilisation? |
Early mitotic divisions (cleavage) which results in daughter cells called blastomeres. No net growth of conceptus despite the cells becoming progressively smallerD |
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Do the blastomeres reamined closed in the zona pellucida? |
Yes |
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When is the Morula formed? |
3 to 5 days after fertilisation |
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|
Why do blastomeres remain so close to each other? |
Because there is limited space where they can because due to the ZP |
|
|
What else occurs during days 3 to 4 post fertilisation? |
Compaction |
|
|
Describe compaction |
blastomeres flatten and develop inside-outside polarity. Tight junctions formed between cells and there is pumping of fluid into morula |
|
|
When does the blastocyst form? |
During days 4-4.5 |
|
|
What occurs during the first differential event? |
2 distinct population of cells develop: Inner cell mass/embryoblast (ICM) and Outer trophoblast |
|
|
Where is the outer trophoblast? |
From wall of blastocyst |
|
|
What happens to the blastocelic cavity after the formation of the trophoblast/ICM? |
It will increase in size via passage of fluid across cells to extracellular space |
|
|
When does the hatcing of the blastocyst occur from the ZP? |
Day 4-4.5 |
|
|
When does hatching usually occur? |
When blastocyst has got from oviduct to uterus |
|
|
What can occur if hatching happens prematurely? |
Ectopic pregnancy - where the blastocysts sticks to wall of uterine tube and implants there |
|
|
What is the role of the Zona pellucida before implantation? |
Holds blastomere in close proximity before compaction and prevents attachment to wall of oviduct prematurely |
|
|
Before cleavage occurs, where is the oocyte moved? |
Region in oviduct called ampulla |
|
|
Where does fertilisation occur? |
Ampulla |
|
|
What does the blastocyst secrete during pre-implantation development? |
Human chorionic gonadotrophin which is a signalling hormone to change uterine endometrium and develop endometrial lining cells to become receptive to blastocyst |
|
|
What does the endometrium express for fertilisation? |
Receptivity markers include Integrins, pinopodes and LIF |
|
|
What does Human chorionic gonadotrophic (hCG) do for the corpus luteum? |
Maintains it to continue the increased levels of progesterone for about 3 months till the corpus luteum degenerates and placenta forms |
|
|
What day does the blastocyst attach to the uterine epithelium? |
Day 5 |
|
|
During days 5-7, what happens to the trophectoderm (trophoblast) cells? |
They differentiate into cytotrophoblasts and syncitiotrophoblasts |
|
|
What does the inner cell mass give rise to? |
Bilaminar disc with 2 layers of cells |
|
|
What are the two layers of cells in bilaminar disc? |
Hypoblast (underneath and closest to blastocylic caivty) and epiblast (on top and at embryonic pole) |
|
|
What does the syncytiotrophoblast invade and where? |
Endometrial stroma between uterine epithelial cells |
|
|
What is the blastocyst structure at implantation? |
Inner cells which give rise to all tissues, outer cells which give rise to embryonic component of placenta |
|
|
By day 9, what has occured? |
Invasion of blastocyst completely into endometrial stroma |
|
|
What occurs in terms of the trophoblast after implantation is complete? |
Rapid proliferation of trophoblast particularly at embryonic pole (where the inner cell mass was present) |
|
|
What forms with the syncitiotrophoblast? |
Lacunae surrounded by the syncitiotrophoblasts |
|
|
What do these lacunae do? |
They connect to form network filled with maternal blood from erosion by syncitiotrophoblast |
|
|
How does the ICM get nutrition fluid? |
Passage across trophoblast to embryonic disc |
|
|
What is the amniotic cavity? |
Cavity formed between blastocyst cavity and cytotrophoblast |
|
|
What is the amnion? |
Cell layer developing along trophpblast border of amniotic cavity and is continuous with epiblast. It is a membrane |
|
|
What is the exocoleomic membrane? |
Cellular membrane fromed between blastocyst caivty and cytrotrophoblast |
|
|
What does the exocoelomic membrane transform the blastocyst membrane into? |
Primary yolk sac |
|
|
Where does the extraembryonic mesoderm form?
|
Between exocoelomic membrane and cytotrophoblast |
|
|
What do the cavities in extraembryonic mesoderm produce?
|
Chorionic Cavity |
|
|
What does the connecting stalk eventually form?
|
Umbilical chord
|
|
|
What happens to the primary yolk sac?
|
It reduces in size and becomes secondary yolk sac |
|
|
How are the bilaminar disc, amniotic cavity and secondary yolk sac suspended? |
Via connecting stalk of extraembryonic mesoderm inside the chorionic cavity |
|
|
What is Gastrulation?
|
formation of trilaminar embryonic discs |
|
|
When does gastrulation begin? |
week 3 of development |
|
|
What forms during gastrulation?
|
Primitive streak in midline of epiblast |
|
|
Where does the invagination of epiblast cells occur? |
Primitive streak |
|
|
What do the epiblast cells do as the primitive streak? |
Displace hypoblast cells and a layer is formed called the definitive endoderm |
|
|
The cells between the epiblast and endoderm layers do what? |
Differentiate into embryonic mesoderm |
|
|
What do the remaining epiblast cells do?
|
Become embryonic ecotderm |
|
|
What forms the primitive streak?
|
thickening of epiblast in midline |
|
|
What are all 3 layers of trilaminar disc derived from? |
Epiblast |
|
|
What forms the notochord?
|
Primitive node at cranial end of primitive streak |
|
|
What does the ectoderm from the trilaminar disc end up forming?
|
Epidermis of skin and neural tube (brain, spinal cord of CNS) |
|
|
What does the mesoderm from the trilamniar disc end up forming?
|
Somites (musculoskeletal system), cardiovascular system, embryonic kidney and attachment to extraembryonic mesoderm |
|
|
What does the endoderm from the trilaminar disc end up forming?
|
Lining of the GIT and respiratory tract
|
|
|
What does the notochord do?
|
Defines axis of embryo and induces ectoderm to form neural plate |
|
|
What is neurulation?
|
formation of the neural tube |
|
|
What is the neural plate formed by?
|
Ectoderm thickening over midline notocord |
|
|
Is all of the ectoderm involved in forming the neural plate?
|
No, only the medial |
|
|
How do the neural folds develop?
|
Lateral edges of the neural plate move superiorly (aka elevate) and medially |
|
|
What is a neural groove?
|
Depression in centre of neural folds |
|
|
Where do the neural folds meet?
|
Medially to form neural tube |
|
|
Where does the tube closure begin?
|
In middle of embryo and moves both cranially and caudally |
|
|
Does the neural tube stay connected to the ectoderm and mesoderm?
|
No, it detaches |
|
|
What are neural crest cells?
|
Cells that fall off when neural tube starts to form
|
|
|
What cells can originate from the neural crest cells?
|
Peripheral nerve cells |
|
|
What is segmentation?
|
formation of somites which are mesodermal blocks that give rise to body segments
|
|
|
When does segmentation occur?
|
Same time as neurulation |
|
|
How does the segment develop? (in which direction) |
Cranial to caudal |
|
|
How is the paraxial mesoderm formed?
|
Thickening of mesoderm which has folds and grooves |
|
|
How is the paraxial mesoderm related to segmentation?
|
It segments into somites |
|
|
What can somites differentiate into? Describe them |
Sclerotome (which develops into bone) and myodermatone which develops further into myotomes (skeletal muscle) and Myodermatomes (CT of skin) |
|
|
What do somites determine in terms of migration patterns?
|
They determine the migration patterns of neural crest cells to form peripheral nerves |
|
|
When does Embryonic Folding occur?
|
Week 4 |
|
|
What sort of embryonic folding occurs in the median plane?
|
cranial and caudal folds (head to toe) |
|
|
What sort of embryonic folding occurs in the transverse plane?
|
Lateral |
|
|
Where does the placenta form? |
Site of implantation of blastocyst into uterine endometrium |
|
|
What are some of the requirements for pregnancy in terms of the maternal side?
|
Maternal adaptions for fetal survival must be made, maternal side has to recognise the pregnancy and not kill it, there must be supply of nutrients by mother for fetus and there is physiological adaptions for parturition as well as preparation for milk synthesis and lactation |
|
|
What is the fetal contribution to the placenta?
|
The chorionic villi which is contact with blood in intervillous space and chorionic plate |
|
|
What is the chorionic villi made up of
|
Trophoblasts (both differentiations of it), extraembryonic mesoderm |
|
|
What is the maternal contribution to the placenta?
|
Decidual tissue which is transformed from endometrial stroma and intervillous space |
|
|
What is the decidua basalis?
|
The only portion of uterine endometrium to which implantation and attachment has occured |
|
|
What is the decidua capsularis? |
The cover site of implantation at most superficial cavity which is in contact with chorion |
|
|
What is the decidua parietalis? |
Remaining endometrium not in direct contact with embryo/fetus |
|
|
What are the functions of the decidual cells of the decidua basalis? |
Restrict trophoblast invasion, provide some nourishment for embryo and fetus, create a separation layer at parturition so corionic villi and placenta are with baby and secrete relaxin |
|
|
What are the regions of the chorion (the fetal contribution to the placenta) |
Chorion Laeve and Chorion frondosum |
|
|
What is the chorion laeve? |
Smooth region with few to no villi
|
|
|
What is the chorion frondosum? |
Villus which produce large, branched villi
|
|
|
What are the 5 types of chorionic villi?
|
Primary, secondary, tertiary, stem/anchoring, branching/floating/free
|
|
|
What are primary villi made from?
|
Trophoblasts only |
|
|
What core do secondary villi have?
|
Mesoderm |
|
|
What do tertiary villi have?
|
Vascular network in central mesodermal core |
|
|
What do stem/anchoring villi do?
|
Attach fetal origin tissue to maternal endometrium. There is a shell of cytotrophoblasts present at attachment sites |
|
|
Why does the mother have no control over whether or not it contributes blood to the intervillis space?
|
Because the cytotrophoblastic shells can erode into spiral arteries that supply endometrial tissue and eat out smooth muscle layer in wall |
|
|
Where do branching villi branch from?
|
Stem villi |
|
|
Does branching continue throughout pregnancy? |
Yes |
|
|
Where is the main site for placental exchange?
|
Branching villi |
|
|
What are free villi bathed directly in?
|
Maternal blood |
|
|
How is the chorion attached to the decidua?
|
via stem/anchoring villi
|
|
|
What are chorionic villi composed of? |
Syncitiotrophoblast, cytotrophoblast, extraembryonic mesoderm and villous blood vessels |
|
|
The efficiency of exchange is facilitated by what? |
Large surface area, thin placental exchange barrier and maintenance of diffusion gradient |
|
|
What does the placental barrier include? |
Only fetal tissues of villus |
|
|
What do the placental barrier layers include? |
Syncitiotrophoblasts, cytotrophoblast, trophoblastic basement membrane, villous CT, villous capillary wall |
|
|
What happens to the placental barrier during pregnancy? |
It decreases |
|
|
What is the endocrine activity of the Placenta? |
Secretes hCG early on in pregnancy, produces steroids and has the capacity to act as an endocrine organ on its own |
|
|
What does the secretion of hCG do? |
enters maternal blood stream and prolongs life of maternal corpus luteum |
|
|
What does the production of steroids (progesterone and oestrogen) do? |
Maintains placental function and prevents premature rejection of placenta by mother |
|
|
Why does the placenta need to act as an endocrine organ? |
Because the Corpus Luteum regresses after 3 months |
|
|
What are readily transferable from the mother to the fetus? |
Nutrients, antibodies, immunoglobulin G, vitamins, harmful substances |
|
|
What are readily transferable from the fetus to the mother? |
waste products, RBC antigens |
|
|
What are non-transferable? |
Bacteria, Herparin and IgM |
|
|
What does the breast develop as? |
Modified apocrine sweat gland |
|
|
When does the breast develop? |
In the fetus - both males and females |
|
|
What gives rise to the inverted nipple structure of the fetus? |
Ectodermal bud from ectodermal tissue |
|
|
What do adipose tissues stimulate? |
Branching of the cord of cells from bud |
|
|
What happens after the branching of the cord of cells? |
Epithelial ductal cells develop |
|
|
What are epithelial ductal cells controlled by? |
Secretion of oestrogen |
|
|
Why don't males get the same degree of the development of breasts as females do? |
Because testosterone drives involution of duct system |
|
|
In males, where do some of the lining cells go in the breast? |
Differentiate into myoepithelial cells and migrate to periphery of the ducts and alveoli |
|
|
What do lactiferous ducts respond to in new borns? |
Maternal homrones |
|
|
What do lactiferous ducts do after responding to maternal hormones? |
Produce secretion of fat, leukocytes and alpha lactalbumin |
|
|
What occurs to breasts during puberty? |
Increase in size and secretion of hormones |
|
|
What hormones are secreted by the breast? |
Oestrogen and prolacting |
|
|
What does the production of oestrogen and prolactin stimulate in the breast? |
Further development of duct system and enlargement of fibro-fatty CT |
|
|
What occurs during the second half of the ovarian cycle, once a woman has reached puberty and until menopause, in terms of the breasts? |
Alveolar buds develop at end of ducts , fluid increases surrounding CT and there is a withdrawal of progesterone at end of ovarian cycle which leads to buds regressing and disappearing |
|
|
What is the development of alveoli driven by during pregnancy? |
Maternal prolactin and progesterone as well as direct hormones from placenta |
|
|
When is the first secretion of lactation? |
Few days after childbirth |
|
|
Is it milk that is secreted? If it isn't, then what is it? |
Colostrum which is different to milk and is more alkaline as well as high in protein content. It also contains antibodies which provide baby with passive immunity |
|
|
What is the second secretion after colostrum? |
Milk |
|
|
What does milk lactation contain? |
lactogerrin, lysozyme, digosaccharides and mucins |
|
|
What does the secretion of milk enable? |
Intestinal bacteria to become established in baby's intesine |
|
|
Why does lactation occur? |
Because of rise in prolactin |
|
|
What produces the milk? |
Alveolar cells |
|
|
What is another hormone, apart from prolactin, that causes milk secretion and ejection? |
Oxytocin |
|
|
What does the suckling of the baby on the nipple stimulate? |
Prolactin and oxytocin |
|
|
What does oxytocin act on? |
Myoepithelial cells that surround alveoli and ducts |
|
|
What does oxytocin cause myoepithelial cells to do? |
Contract which forces milk into lactiferous ducts |
|
|
What are the two ways milk can leave? Describe them |
APOCRINE - leaves through secretion of lipids and is membrane bound MEROCRINE - leaves through secretion of proteins and carbohydrates and is exocytosed |
|
|
What is cessation of lactation and what occurs? |
No suckling = cessation which means oxytocin and prolactin drop in response. Where there's no stimulation of the glandular alveoli, the cells will undergo apoptosis |
|
|
What replaces duct and alveolar cells when there is cessation of lactation? |
Adipose tissue |
|
|
How is Fibrocystic disease identified? |
Mammography |
|
|
What happens when you get Fibrocystic disease? |
Hyperplastic unequal growth of ducts and CT |
|
|
What does invasive adenocarcinoma breast cancer develop from? |
Terminal ducts and lobular units (epithelial tissue) |
|
|
What do some of the cancerous epithelial cells pass through? |
Basement membrane and infiltrate the CT where they can migrate to the lymph vessels |
|
|
Where else can breast cancer metastasise? |
Lungs, bone and liver |
|
|
What is the prostate? |
gland size of a large walnut that sits on the base of bladder |
|
|
What passes through the prostate? |
Prostatic urethra |
|
|
What is the Prostate made up of? |
Branched glands |
|
|
What are the branched glands of the prostate arranged in? Describe each of them |
3 zones |
|
|
Describe the appearance of these branched glands |
Relatively wide lumen with irregular profile lined by 1-2 layers of psuedostratified cells. Also surrounded by fibrous CT and smooth muscle. |
|
|
What does the prostate have a large amount of? |
Fibromuscular tissue called Stroma |
|
|
What is the main function of the prostate? |
Produce and store prostatic fluid in glands |
|
|
What is prostatic fluid? |
Fluid that contributes to 1/3 semen |
|
|
How does prostatic fluid contribute to sperm? |
Contributes to the coagulation of it after ejaculation |
|
|
What are the components of prostatic fluid? |
Increase concentration of citrate, proteolytic enzymes, acid phosphtase and prostate specific antigen |
|
|
What is the main change in the prostate as men age? |
The development of Benign Prostatic Hyperplasia |
|
|
When does Benign Prostatic Hyperplasia usually start? |
50yrs old |
|
|
What does Benign Prostatic Hyperplasia affect? |
Transitional and central glands |
|
|
What is a result of increase epithelium during benign prostatic hyperplasia? |
Increase activity therefore prostatic concretions form in lumens of glands and can become calcified |
|
|
What is the result of the calcification occuring in BPH? |
Exerts pressure on urethra therefore difficulty in urination and can lead to renal disorders |
|
|
Where does prostatic cancer arise? |
Outer prostatic glands and occasionally advanced tumour cause urinary obstruction |
|
|
What are the common sites of prostatic cancer metastases? |
Pelvic lymph nodes and bones |
|
|
How is prostatic cancer detected? |
Serum levels of Prostate Specific Antigen |
|
|
What is prostatic cancer usually dependent on? |
Testosterone |
|
|
How would you treat prostatic cancer? |
Blocking testosterone |
|
|
What are the causes of infertility in females? |
Disorders of ovulation and absence of menstruation Tubal Obstruction Uterus Cervic Loss of Ovarian Reserve |
|
|
What are the underlying causes of disorder of ovulation and absence of mensutration? |
High gonadotrophin secretion Low gonadotrophin secretion Gonadotrophin insensitivity Follicular cysts Polycystic Ovarian Syndrome Short Luteal Phase |
|
|
What may high gonadotrophin secretion indicate? |
Ovarian failure because there's no feedback of steroid hormones produced from growing follicles Premature menopause |
|
|
What may low gonadotrophin secretion indicate? |
Problem with hypothalamus or pituitary gland |
|
|
What occurs during gonadotrophin insensitivity? |
Cells are unable to recognise gonadotrophin therefore will not be able to elicit an affect on its target cells |
|
|
What does it mean if gonadotrophin can't elicity its affect on its target cells? |
Oestrogen will not increase during follicular phase of ovarian cycle therefore follicle will not mature |
|
|
Why can follicule cysts interfere with fertility? |
Because they interfere with normal ovulation |
|
|
What does Polycystic Ovarian Syndrome mean is happening in the body? |
Increase testosterone and increase BMI and increase hairyness |
|
|
What can cause Polycystic Ovarian Syndrome? |
Adrenal gland Theca Interna cells are under the influence of LH and producing testosterone which is being converted to follicular cells under influence of FSH |
|
|
Why does a short Luteal phase contribute to infertility? |
Because there is not sufficient support for fertilisation |
|
|
What are the causes of tubal obstruction? |
Obstruction and infection |
|
|
What problems with the uterus can contribute to infertility? |
Poor endometrial receptivity or endometriosis |
|
|
What is endometriosis |
Inflammation of endometrium |
|
|
Why can the cervix influence infertility? |
It can be too hostile of an environment |
|
|
Why does a loss of ovarian reserve contribute to infertility? |
Because there aren't enough eggs to fertilise due to age |
|
|
What causes a failure of the oocyte to release from the follicle? |
Not enough LH receptors which means won't be able to produce high levels of oestrogen therefore feedback will not work |
|
|
What happens if you don't have LH sensitivity? |
You won't get the increase LH surge therefore no ovulation and follicle doesn't release ooxyte |
|
|
Where does LH bind in females? |
Thecal cells |
|
|
Can there be a failure of the hypothalamic-Pituitary-Gondal Axis? |
Yes, it can lead to infertility |
|
|
What can cause failure of sperm transport in females? |
Infection that results in blockage in oviduct |
|
|
What happens if there is a blockage in the oviduct? |
Oocyte may be picked up but sperm cannot make their way to the oocyte |
|
|
What is the implantation window? |
Endometrium is maximally receptive to implantation |
|
|
What happens if you miss this window? |
You could miss implantationW |
|
|
What can lead to missing the implantation window? |
Hostile or unperceptive uterine environment |
|
|
What are the causes of subfertility in men? |
Impaired secretion of gonadotrophin Sperm Defects Accessory sex gland malfunction Inadqueate venous drainage and dilation of spermatic vein Testicular Insult or Trauma Obstruction of epididymus or no vas deferens Lifestyle factors |
|
|
What lifestyle factors contribute to subfertility? |
BMI, smoking, drug use, excess alcohol |
|
|
How can the obstruction of the epididymis or no vas deferens contribute to subfertility? |
Ducts may become fibrotic |
|
|
What are some trauma's that can happen to the testes that can lead to subfertility? |
Infection, irradaition, anti-miotic agents, chemotherapy, insecticides, heavy metals |
|
|
What can impaired secretion of gonadotrophins lead to? |
Bring about hypogonadotrophic hypogonadism which means small glands become tissues and don't develop |
|
|
What sort of sperm defects can lead to subfertility? |
Low number, no or reduced motility, abnormal sperm morphology |
|
|
Why does inadequate venous drainage and dilation of spermatic vein lead to subfertility? |
Because the pressure environment is not ideal at maintaining tissue |
|
|
What are the parameters to assess semen? |
Concentration of sperm, Motile %, Living % and morphology |
|
|
What are the 2 main types of Assisted Reproductive Technology? |
IVF (in Vitro fertilisation) and ICSI (intracytoplasmic sperm injection) |
|
|
What do the ART techniques usually rely on? |
Cryopreservation of gametes |
|
|
How is the hormonal induction of follicular development done? |
Administration of antiestrogen which suppressed gonadotrophin secretion. Then, this drug is withdrawn and therefore the rebound surge occurs which leads to ovulation |
|
|
What are the 6 steps of IVF? |
1. Ovarian hyperstimulation 2. Oocyte retrieval/pick-up 3. Semen preparation 4. Insemination 5. Assessment of Fertilisation 6. Embryo Cleavage and Transfer |
|
|
How is Ovarian hyperstimulation achieved? |
Use GnRH agonist followed by human menopausal gonadotrophin which stimulates growth of oocyte Once you get growth, you then administer hCH to prepare follicles for ovulation |
|
|
What route is oocyte retrieval and pick-up usually done by? What is guided by? |
Transvaginal guided by ultrasound |
|
|
Once the oocyte is located through the transvaginal route, what happens? |
It is then sucked up from follicles and put in culture medium |
|
|
What happens once you've collected the sperm? |
Wait until it coagulates and liquifies then centrifuge it to get sperm pellet |
|
|
How do you determine the best sperm from the sperm pellet? |
Add density gradient |
|
|
Is the concentration of sperm insemination high or low? When is the sperm added? |
High and added when oocytes are at metaphase 2 |
|
|
How are oocytes examined after insemination? |
Removed and examined for pronuclei and polar bodies |
|
|
When is the embryo placed in the recipients uterus? |
When the oocyte is at 2 or 4 cell stage |
|
|
Why is Embryo freezing used? |
To slow cropreservation |
|
|
How is ICSI carried out? |
Sperm is immobilised and sucked up in pipette then injected into oocyte |
|
|
What are the 3 main ways to control fertility? |
Sterilisation, Contraception and Induced pregnancy termination |
|
|
What are main contraceptive methods used world wide? |
Oral, female sterilisation, injectible steroids, IUDs, male condom |
|
|
What is a Vasectomy? |
Sterilisation method where tubes are cut and blocked at location close to scrotum |
|
|
What is a tubal occlusion? |
Fallopian tube in isthmus region is closed off through being clipped, banded, cauterised, tied or cut |
|
|
What is a hysterectomy? |
Blating lining of uterus is removed, or whole uterus is removed |
|
|
What are the natural methods of fertility control? |
Rhythm method and coitus interruptus |
|
|
What are the barrier methods of contraception? |
Condom, cervical cap and diaphragm |
|
|
How does the diaphragm and cervical cap work? |
Device that fits inside vagina and prevents sperm from passing through entrance of cervic |
|
|
What are Oral Contraceptives? |
Synthetic variants of natural oestrogen and progesterone |
|
|
What is the difference between a monophasic regime and a bi/triphasic regime? |
Monophasic = releasing same amount of hormones over a cycle Bi/triphasic = can alter concentration of oestrogen relative to progesterone |
|
|
What are the target sites of oral contraceptives? Describe its actions there |
Hypothalamic-Pituitary axis - by negatively feedback on GnRH and gonadotrophins Uterus and Cervix - cause endometrial thinning and bringing about changes in glycogen and cervical mucus |
|
|
How are the mono, bi and triphasic regimes based? |
Around 28 day cycle with 21 active pills and 7 inactive tablets |
|
|
How do the combined oral contraceptive act on hormone levels? |
Circulating levels of synthetic hormones suppress LH and FSH by having negative feedback of gonadotrophins |
|
|
What does the suppression of LH and FSH have on the follicles? |
Have inability to mature to preovulatory stage therefore increased levels of oestrodiol not produced therefore no LH surge therefore no ovulation |
|
|
What does progestagen act on? |
Cervical glands. It alters the viscosity of mucous to make it thicker and impenetrable to sperm |
|
|
What effect does the combined oral contraceptive have on the uterine endometrium? |
Thins it and alters uterine secretory activity by reducing secretion of glycogen, reducing receptivity to blastocyst and reducing capability to support implantation |
|
|
How does the Progestagen only pill work? |
Works by thickening cervical mucous and prevents sperm from entering the uterus |
|
|
What is difference between the injectable contraceptives and the oral ones? |
Injectable ones last longer |
|
|
What does the vaginal ring have as its features? |
Impregnated with progesteron or EE and progestagen. It induces hostile mucous to prevent sperm penetration |
|
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How do IUDs prevent pregnancy? |
Induce low grade inflammatory response so leukocytes migrate into uterine lumen and change intrauterine environment to reduce sperm transport to UTJ. It also impairs blastocyst viability, implantation and decidualisation |
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What do active IUDs include? |
Copper or Porgestagen |
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What is RU486? |
Substance used to cause a miscarriage early in pregnancy and to treat range of medical conditions including endometriosis and cancer of uterus |
