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81 Cards in this Set

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Give an outline of the process from sperm and egg to embryo development.
Meiosis of sperm and meiosis of egg.

Ejaculation of sperm and ovulation of egg.


Fertilisation - egg activation and pronuclear formation

Embryo development
Define fertilisation.
Fertilization converts two terminally differentiated cells into a totipotent zygote, capable of forming all cell types of the body.

Fertilisation is the process that initiates the union of a sperm and oocyte in order to form an embryo.

- Spermatogenesis and oogenesis is the process to prepare gametes for fertilisation
- Meiosis produces sperm and egg that are haploid - their union produces diploid embryos
Describe the hormonal regulation of ovulation.
Ovulation is initiated by increased hormone leutinizing hormone (LH) which provokes the mature follicle to rupture and release the oocyte. LH also initiates resumption of meiosis.
Describe the process from a primary oocyte to a secondary oocyte.
An LH surge causes the Germinal Vesicle (GV) in a primary oocyte to break down.

Prior to fertilisation the egg has initiated meiosis and becomes an arrested secondary oocyte at Metaphase II.

There is the extrusion of 1st polar body.
What is the Zona Pellucida (ZP)?
glycoprotein coat that surrounds the oocyte.
Describe the steps in which sperm acquires the ability to fertilise.
1. Sperm capacitation

2. Binding of sperm to the egg outer coat or ZP
- sperm undergoes the acrosome reaction
- Zona contains specific ZP3 receptor proteins to prevent inter-species fertilization.
- ZP3 induces the acrosome reaction to expose the ZP2 binding sites on the inner acrosome membrane.

3. Binding of sperm to the egg plasma membrane
- release of cortical granules - block to polyspermy
- increase in calcium - wave
- resumption of female 2nd meiotic division
- changes in sperm chromatin structure
- formation of male and female pronuclei
- activation of embryo development
List the stages of sperm and egg transport.
1. Sperm deposited in vagina (250 000 000)

2. 100 000 sperm reach uterine cavity

3. 50 or less sperm arrive at distal end of fallopian tube

4. Delay at Ampullary-Isthmic Junction where fertilisation occurs (days 1-2)

5. Delay at utero-tubal junction (days 2-3)

6. Egg enters uterine cavity as a morula (days 3-4)

7. Blastocyst implants (day 7)
Describe what happens when sperm moves through the female reproductive tract and acquires the ability to fertilise.
- Minutes after intercourse human sperm leave semen and swim into cervical canal
- semen contains secretions from accessory glands - due to structural proteins
- degraded by prostate specific antigen PSA (serine protease secreted by prostate)
- sterols removed, which increase sperm plasma membrane. permeability to ions (such as calcium) and expression of receptors and binding of stimulatory ligands (SABP)
- As sperm migrate, those that are abnormal or less "healthy" die or become phagocytised by infiltrating lymphocytes.

THUS the sperm that enter into uterus are more homogenous and more likely to fertilise.
What two important changes do sperm undergo in the ampullary region of oviduct?
1. Hyperactivation (may help sperm to penetrate ZP)

2. Capacitation
What are the receptors on the oocyte that bind to sperm?
Why is ZP3 critical for sperm binding to the zona pellucida?
- ZP3 - thought to be involved in species specific barrier to fertilisation
- Recent paper showed that mice eggs with a human ZP3 protein did not result in human sperm binding. Although mouse sperm did
- This may have been due to post-translational modifications of the protein, such as glycosylation, which was established in the mouse.
Describe the acrosome reaction.
- Involves reorganisation of membranes in the head of sperm
- Multiple fusions occur between outer region of acrosomal membrane and the plasma membrane that overlies the acrosome
- Loss of membrane reveals inner acrosome membrane with form a a new head membrane
- contents in the acrosome, such as hyaluronidase and proteases help sperm to penetrate through ZP glycoprotein coat

THE SIGNALS THAT CAUSE THE ACROSOME TO REACT ARE NOT KNOWN - binding to ZP3 induces acrosome reaction.
What is the secondary binding of sperm?
Secondary binding of sperm is to ZP2 on the oocyte zona pellucida
How is the egg activated?
Sperm releases a factor (as yet unknown) that initiates calcium waves into the oocyte.

Calcium pulse initiated by IP3 (inisitol trip phosphate)

The Calcium release
- initiates cortical granule release - which alters membrane to inhibit further sperm binding.
- initiates the resumption of meiosis - resulting in the extrusion of the 2nd polar body.
- initiates alterations in sperm chromatin and ultimately, formation of the zygote and subsequent embryo.
How does one cell - the fertilised egg become a multicellular organism?
List the stages.
Mammilian preimplantation embryo development
- uniting of maternal and paternal genomes
- activation of the embryo genome
- cell division
- setting up two cell types (differentiation)
- blastocyte formation
Describe the activation of the embryo genome.
Embryonic genome activation (EGA)
- The global activation of thousands of genes
- Critical for embryo development
- 40% of maternal mRNA is degraded by the 2-cell stage in the mouse
- occurs at teh 2-cell stage in the mouse
Describe cell division.
Cleavage occurs slowly.

In mouse every 12 hours
Describe setting up two cell types (differentiation).
Formation of blastocyst involves setting up two cell types:

Inner cell mass cells form EMBRYO

Tophectoderm cells from PLACENTA
Describe blastocyst formation.
Formation of a blastocoelic cavity

Na/ATPase pump produces fulid which forms a cavity as the blastocyst expands.

The blastocyst hatches and implants into the endometrium.
What are some statistics on human embryo development?
- 15% embryos die
- 30% women abort very early (prior to implantation)
- overall spontaneous abortion 45% (approx 50% due to chromosome abnormalities)
What are some statistics on infertility and fertilisation in vitro (IVF)?
29688 women in UK underwent IVF with 10424 children born. (35%)

3158 underwent donor insemination with 825 children born (24%)
What are some statistics on male infertility?
- 20% infertility cases due to male infertility
What does ICSI stand for?
Intracytoplasmic Sperm Injection
What is the optimal time for human pregnancy?
Among healthy women trying to conceive, nearly all pregnacies can be attributed to intercourse during a six-day period ending on the day of ovulation. For practical purposes, the timing of sexual intercourse in relation to ovulation has no influence on the sex of the baby.
What is the Australian Legislation about the human Embryo?
Research Involving Embryos and Prohibition of Human Cloning Bill 2002

Prohibited embryos and practices
The Prohibition of Human Cloning Act 2002 prohibits the creation, placing in the human body or the body of an animal, import or export of a human embryo clone, whether or not it did not or could not have survived.

The act also prohibits a number of other practices as follows:
- Creating a human embryo by a process other than by fertilisation of a human egg by a human sperm, or intentionally developing such an embryo.
- Creating a human embryo outside the body of a woman for any purpose apart from attempting to achieve a pregnancy
- Creating or developing any of the following embryos:
> a human embryo with genetic material from more than two people
> a human embryo created using precursor cells from a human embryo or fetus
> a human embryo in which the genome has been altered in any way that could be inheritied by the descendants of the embryo
> a chimeric or hybrid embryo
> developing a human embryo outside the body of a woman for more than 14 days, excluding any period when development is suspended.
Define an embryo.
"offspring of an animal before birth; undeveloped; immature"

biologically the creation of an embryo marks the beginning of life

A human embryo is a descrete entity that has arisen from either:
1. The first mitotic division when fertilisation of a human oocyte by a human sperm is complete; or
2. Any other process that initiates organised development of a biological entity with a human nucelar genome or altered human genome that has the potential to develop up to, or beyond, the stage at which the primitive streak appears; and has not yet reached eight weeks of development. (NHMRC)
What are the stages of the embryo?
Zygote (fertilised cell)
0 days

Morula (cells divide)
3-4 days

Blastula (hollow ball of cells)
5-6 days

Gastrula (layers form)
12-16 days

Development of organs and tissues
What are the stages of control of follicular development?
Primordial follicle pool
Follicle growth initiated (antrum forms)
Gonadotrophin responsive
Gonadotrophin dependent
Ovulatory follicle
Describe the selection of follicles.
- 2 to 3 times number of follicles destined to ovulate are initially selected
- Antrum formation
- Follicles beome responsive to gonadotrophins
- Follicles acquire FSH receptors
- Follicles enter rapid growth phase
Describe the dominant follicle.
- Ovulatory quota will become dominant and will be ovulated, usually one in humans
- Selection of dominant follicle occurs at about day 6 of cycle
- Remainder of selected follicles become atretic
- Further recruitment of follicles to gonadotrophin phase is blocked
What are 3 distinctive features of the dominant follicle.
1. Increased estrogen and inhibin production.
2. Increased mitogenic activity in granulosa cells.
3. Decreased dependence on FSH
Why does the dominant follicle have a decreased requirement for FSH?
1. Increased blood supply (VEGF).
2. Acquisition of LH receptors - induced by FSH and an increase in concentration estrogen during selection.
3. LH stimulation maintains high cAMP levels in the cells of the dominant follicle which counteract the effects of the decreased FSH levels.
Describe the Follicular (proliferative) phase.
Under influence of estrogen
- Proliferation of glandular, stromal and vascular endothelial cells
- Thickening of mucosa
- More prominent in superficial 2/3's of functional layer
- Subsides by days 11-14
Describe post ovulatory events.
Within 3 days of LH surge
- proliferation of endometrium ceases
- glands become tortuous
- secretory activity of glandular cells increases
- maximum activity at 7 days
- stromal oedema occurs in preparation for implantation (VEGF)
Why does the corpus luteum fail?
- In humans - don't really know
- Many species - prostaglanding F2alpha
- Gradual decline and demise?
What is menorrhagia?
Menorrhagia is an abnormally heavy and prolonged menstrual period.

Causes may be due to abnormal blood clotting, disruption of normal hormonal regulation of periods or disorders of the endometrial lining of the womb. Depending upon the cause, it may be associated with abnormally painful periods (dysmenorrhoea).
What is normal blood loss?
- 40mL
- 10 to 80 mL
- 3 to 5 days
What is abnormal blood loss?
> 80 mL
List some of the causes of menorrhagia.
Endometrial - polyp
Submucosal - fibroid
Endometrial - hyperplasia
Endometrial - adenocarcinoma

Anovulatory - DUB
Ovulatory - DUB

DUB = dysfunctional uterine bleeding
PCOS = polycystic ovary syndrome
What is fibrinolysis?
Fibrinolysis is the process where a fibrin clot, the product of coagulation, is broken down. Its main enzyme, plasmin, cuts the fibrin mesh at various places, leading to the production of circulating fragments that are cleared by other proteinases or by the kidney and liver.
Describe fibrinolysis in menorrhagia.
- Menstrual blood does not clot
- Fibrinolysis
- Due to endometrial plasminogen activaotr
- This is increased in menorrhagia
- Tranexamic acid (4gm for 4/7) inhibits Endometrial Plasminogen Activator
What medication can be given for menorrhagia?
- 5mg
- 12/7 at least

Medroxyprogesterone acetate
- 5mg
- 12/7 at least

Cox-1 and cox-2 inhibitors

Mefenamic Acid
- 1gm 8 hourly
- Begin - 4/7 before menses
- Stop - cycle D4
What are some non-medicinal treatments of menorrhagia?
- cervical dilation
- uterine curettage
- a diagnostic test
- office hysteroscopy & endometrial sampling

Endometrial ablation
- removal of the endometrium
- through the vagina
- day surgery

- removal of the uterus
- abdominal
- vaginal
What are 3 ways of removing endometrium in patients with menorrhagia?
a) Endometrial resection using a rectoscope loop is favoured for menorrhagia due to submucosal fibroids

b) Endometrial ablation is recommended for menorrhagia due to dysfunctional uterine bleeding

c) laser endometrial extirpatio is now uncommonly used.
What is hyperprolacinaemia?
Elevated prolactin.
What are the clinical features of prolactin excess?
Inadequate Luteal phase
Early miscarriage
Estrogen deficiency
What are the clinical features of androgen excess?
Hirsutism - hair growth is increased and/or present where it is not normally found

Virilization (or masculinization)
1. Defeminization
- decrease in breast size
- amenorrhoea
- loss of female body contours
2. Masculinization
- increased skeletal muscle mass
- temporal balding
- acne
- deepening of voice
- clitoral enlargement
What are the criteria for diagnosing PCOS?
Menstrual irregularity
Hyperandrogenism - clinical & biochemical
Exclusion of other causes
What are the menstrual irregularities seen in PCOS?
Peripubertal onset or after weight gain
- irregular periods
- endometrial hyperplasia
- endometrial carcinoma
- amenorrhoea
- negative P challenge
What are the symptoms of hyperandrogenism seen in PCOS?
- Hirsuitism - upper lip, breast, lower abdomen
- Acne
- Temporal balding
- Increased muscle mass
- Voice deepening
- Clitoromegaly
What is the clinical presentation of PCOS?
Menstrual irregularity
What history needs to be taken for PCOS?
Menstrual history
Time course of symptoms
Weight history
Family history
What examination needs to be done for PCOS?
BMI and body habitus
Abdomen and pelvis
What is the link between obesisty and PCOS?
- half of those with PCOS are obese
- 20% of these have IGT or NIDDM by 40 years - acanthosis nigricans
- Predisposition to heart disease - lipid abnormalities
What is the link between PCOS and NIDDM?
- women with PCOS have a 30% incidence of NIDDM
- age, ethnicity and weight matched ovulatory women have a 10% incidence
What is the link between infertility and PCOS?
- not all women
- may take longer to conceive
What are the hypotheses for PCOS?
- LH
- Insulin
- Ovarian
- Combination
What do you do to make a diagnosis for PCOS?
What causes need to be excluded from PCOS?
What other tests should be done in relation to PCOS?
Fasting lipid profile
What is treated in PCOS?
Weight loss
Menstrual irregularity
Insulin resistance
How do you treat menstrual irregularity for PCOS?
Sequential progestogen
How do you treat hirsutism for PCOS?
Cosmetic measure
Pharmacologic therapy
- 6/12
- Anti-androgens
How do you treat infertility for PCOS?
Clomiphene citrate
Ovarian drilling
How do you treat insulin resistance for PCOS?
What does syndrome X entail?
Lipid abnormalities
Type 2 diabetes
Endometrial hyperplasia
Endometrial carcinoma
What are the two phases in the ovarian cycle?
Follicular phase
Luteal phase
What are the steps in the Ovarian cycle
- D1-D5
- Follicle growth trajectory
- ?? 200 each cycle
- a cohort of follicles

- winnowing by atresis
- day 5-8
- random
- to 1 follicle

- functional dominance
- D8 to ovulation (D14)
- inhibits competing follicles

- follows LH surge
- +36 hours
Which two chemicals affect the dominant follicle?
Inhibin A&B
Which cheminal affect the corpus luteum?
12-16 day lifespan
Dominance & regression
HCG - fertile cycle
What are the layers of the uterus?
- elastic
- muscular

- proliferative
- secretive
- glands & stroma
What does the endometrium consist of?
- single columnar epithelium
- glands - progesterone dependent
- stroma - decidua
- spiral arterioles
What are the endometrial hormones?
What happens in puberty in relation to the menstrual cycle?
- Medial basal hypothalamus
- Pulsatice GnRH Release
- increase FSH release
- increase LH release
- anterior pituitary
List the stages of puberty
I - Thelarche
II - Growth spurt
III - Adrenarche
IV - Menarche
What occurs in each stage of puberty?
I - Thelarche - Breast buds (9-13 years)
II - Growth spurt
III - Adrenarche - Axillary/pubic hair
IV - Menarche (11-15 years)
Describe the estradiol receptor.
- an acidic protein in cytoplam: 70KD
- transforms into a DNA-binding form
- high affinity binding (Kd = 0.1mm)
- E2>x10 Estradiol & estrone
Describe the progesterone receptor.
- 2 protein dimer
- high affinity (KD= 1nm)
- synthesised by estradiol action
- ~12000 progesterone receptors per cell
- peak at day 20
List some prostaglandins.
- uterine hormones
- endometrial origin
- linoleic acid --> arachidonic acid
- cyclo-oxygenase a key synthetic enzyme
- PGF2D & PGE2
Describe the physiology of prostaglandins.
- Dilate the cervix
- contract the myometrium
- vasoconstrict
- cause period pain: dysmenorrhea
- causes labour
- misoprostol - a PGE analogue
Where does endometrial prolactin come from?
- from dicidua - D21 onwards
- early pregnancy - angiogenic
- late pregnancy - protects amniotic fluid