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180 Cards in this Set
- Front
- Back
What is gestational age?
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- calculated from first day of menstral cycle (LNMP)
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What is conceptional age?
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- calculated from day of fertilization
- 2 weeks less than gestational age |
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What is expected date of delivery?
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- add nine months and 7 days to LNMP (gestational age)
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Embryo
Fetus Neonate Infancy |
1. 1st to 8 weeks
2. 9th week onwards 3. First 28 days after birth 4. First year of life |
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What is gametogenesis?
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Conversion of primodial germ cells into mature male and female gametes via meiosis and cytodifferentiation
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Development of Primordial germ cells?
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Yolk sac --> gonadal ridge (dorsal body wall)
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What do primordial germ cells induce?
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- primary sex cords which lead to male and female gonads
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What happens if primordial ger cells don't migrate to the gonadal ridge?
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- they form tumors
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When are the gonads indifferent?
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- before 7 weeks
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What is sex determined by?
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- SRY gene on the short arm of the y chromosome
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What does the SRY gene code for?
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- Testis Determining Factor
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1. N number
2. Ploidy |
1. number of like or homologus DNA strands
2. number of like or homologus chromosomes |
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Aneuploidy
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- one or a few chromosomes above or below the normal number
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Where does Meiosis occur?
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- in the germ cells
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What are the products of meiosis?
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- 4 gametes with 23 chromosomes and 1N DNA
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What are the stages of Meiosis 1?
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- synapsis: pairing of 4 homologous duplicated chromosomes
- crossing over: exchange of segments of DNA - alignment: 46 chromosomes separate from each other - cell division: 2 secondary gametocytes are formed (23, 2N) |
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What are the stages of Meiosis 2?
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- No synapsis and crossing over
- alignment: 23 duplicated chromososmes align at metaphase plate - Disjunction: 23 chromosomes separate to form 23 sing chromosomes - Cell division: 4 gametes (23 single chromosomes, 1N) |
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Stages of spermatogenesis
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1. Spermatocytogensis
2. Meiosis 3. Spermiogenesis |
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When do primordial germ cells arrive at the gonads?
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- Week 4
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How long to primordial germ cells stay dormant in males?
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- week 4 - puberty
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What happens to primordial germ cells at puberty in Males?
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- differentiate into type A spermatogonia
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How do Type A spermatogonia form Type B spermatogonia?
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- via mitosis
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What do Type B spermatogonia give rise to?
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- primary spermatocyte
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What do primary spermatocytes do?
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- undergo meiosis to form secondary spermatocytes
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What do secondary spermatocytes give rise to?
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- 4 secondary (halploid) spermatids which give rise to mature sperms
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What is spermiogenesis?
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- from late spermatid to spermatozoa
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What is sperm capacitation?
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- capacity to fertilize an oocyte
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Where does capicitation occur?
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- Female genital tract
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How does capacitation occur?
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- removal of surface coating proteins and unmasking of enzymes
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Where is sperm motility aquired?
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- epidydimis
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When do primordial germ cells arrive in gonads and differentiate into oogenia?
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- week 4
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When are all primary oocytes formed?
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- 5th month of fetal life
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How long do primary oocytes remain dormant?
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- from prophase of meiosis 1 till puberty
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What occurs to primary oocytes at puberty?
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- completes meiosis 1 to form two daughter cells
- secondary oocyte and first polar body (later degenerates) |
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What occur during meiosis 2 involving secondary oocyte?
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- secondary oocyte stops at metaphase of meiosis 2
- if fertilization occurs, then completes meiosis 2 to form mature oocyte and secondary polar body |
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Increased paternal age is associated with what chromosomal abnormality?
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- Achondroplasia
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What chromosome abnormality is Down syndrome?
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- Trisomy 21
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What is Down Syndrome associated with?
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1) esophageal atresia
2) Congenital Heart Disorders 3) abnormal facial features 4) esophageal atresia 5) acute lymphocytic leukemia 6) Alzheimers disease |
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What are symptoms of Turners syndrome?
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1) web neck
2) widely spaced nipples 3) infertility |
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Kleinfelter's Syndrome
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- gynecomastia
- XXY |
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What is the ovarian cycle?
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- changes in the ovary
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What is the menstrual cycle?
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- changes in the endometrium
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What hormones control Ovarian cycle?
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- Gonadotropins: FSH and LH
- from the pars distalis of the pituitary gland |
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What occurs during Ovarian cycle?
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- Only one oocyte of several primordial follicles matures and ruptures during ovulation
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What is corpus luteum?
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- After ovuluation, the follicle is converted to corpus luteum in which oocyte is released
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What are the three stages of Ovarian cycle?
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- Follicular phase: 1-13 days
- Ovulation phase: 14 (rupture of follicle releasing oocyte) - Luteal phase: 15-28 (presence of corpus luteum activity) |
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Where does follicle rupture in ovulation?
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- at stigma at center of swelling of follicle
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When is secondary oocyte released with granulosa cells?
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- 12-24 hours after LH surge
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What is corpus luteum formed under the influence of?
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- LH
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What does corpus luteum secrete?
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- progesterone and small amounts of estrogen
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What happens to corpus luteum if no fertilization occurs?
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- forms corpus albicans by 10-12 days
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What happens to corpus lutuem if fertilization occurs?
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- continues to first 20 days of pregnancy as corpus luteum of pregnancy
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What hormone is needed to maintain pregnancy?
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- progesterone
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What hormones influence Menstrual cycle?
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- estrogen and progesterone
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What occurs during first five days of menstrual cycle?
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- uterus sheds endometrium
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What is the proliferative phase of mestrual cycle?
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- Epithelium regenerating under influence of estrogen
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What is secretory phase of menstrual cycle?
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- secretions under influence of progesterone
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What are two layers of endometruim of uterus?
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1) stratum functionalis: undergoes cyclical changes, shed during menses
2) stratum basalis: gives rise to basal layer, permanent layer |
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What is the menstrual phase of menstrual cycle?
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- 1st day of menstrual cycle: lasts 3-5 days, functional layer sloughed off
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What is proliferative phase of menstrual cycle?
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- last 9 days
- growth of ovarian follicles - controlled by estrogen secreted by follicle |
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What is secretory phase?
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- 13 days, progesterone dependent
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What happens in secretory phase if fertilization occurs?
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- blastocyst implants about 6th or 20th day of normal cycle
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What happens in secretory phase if fertilization does not occur?
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- secretory endometrium enters an ischemic phase
- falling hormone levels (especially progesterone) cause cconstriction of arteries in endometrium |
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What is fertilization?
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- contact of sperm with secondary oocyte
- ends with fusion nuclei of sperm and ovum |
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How does sperm penetrate oocyte?
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- acrosomal cap of sperm head releases enzyme hylarunidase that allows passage through corona radiata
- acrosome also release acrosin and neuraminidase which lyses zona pellucida - sperm passes through zona and zona/cortical reaction occurs that makes the plasma membrane of the ovum impermeable to other sperms |
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What is a female pronucleus?
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- Nucleus of mature oocyte
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What is male pronucleus?
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- Nucleus of the sperm (tail denerates)
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What is a zygote?
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- Fusion of male and female pronucleus
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When is fertilization complete?
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- Within 24 hours of ovulation
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When is Early Pregnancy Factor produced and what is its function?
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- 24-48 hours after fertilization
- produced by ovary - immunosupressant, prevents zygote from being destroyed |
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What is In Vitro Fertilization?
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- sperm cultivated with unfertilized egg in test tube and then transplanted into uterus
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What is Gamete Intra Fallopian Transfer? (GIFT)
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- gametes of male and female injected into female’s fallopian tube for fertilization to occur
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What is Zygote Intra Fallopian Transfer? (ZIFT)
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- egg is fertilized outside the body and then implanted into fallopian tube
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What is Intracytoplasmic sperm injection? (ICSI)
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- fertilization in which a sperm is directly injected into an egg to achieve fertilization. ICSI done for male infertility
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What is Intrauterine insemination?
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- a catheter tube is inserted through cervix into uterus to deposit sperm
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What is a blastula?
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- Division of zygote which will implants in uterus(blastomeres)
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What is cleavage?
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- Process in which zygote divide within 24 hours of fusion
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What is compaction?
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- Blastomeres align against each other by interacting with surface glycoproteins
- Outer cells form tight junctions which form trophoblast - Inner cells develop gap junctions which develop embryo |
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What is Morula?
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- Solid ball of 12 or more blastomeres
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What does trophoblast give rise to?
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- The placenta
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What is a blastocyst cavity?
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- Fluid filled spaces between central blastomeres
- Increases in size as zona pellucida degenerates |
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Where does blastocyst attach?
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- Endometrium adjacent to embryonic pole
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When does this attatchment occur? (implantation)
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- 6 days post fertilization
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What does trophoblast differentiate into?
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- Inner cytotrophoblast
- Outer synctiotrophoblast (invades endometrium during implantation) |
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When is blastocyst completely embedded in uterus?
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- 10th-11th day
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Where does normal implantation occur?
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- Upper posterior wall of the uterus
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What is an ectopic pregnancy?
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- Implantation anywhere apart from the uterus
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Where is the most common place for ectopic pregnancy?
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- Fallopian tube
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Where is amniotic cavity located?
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- At embryonic pole b/w trophoblast and epiblast
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What does the inner cell mass differentiate into?
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- Epiblast: facing amniotic cavity
- Hypoblast: facing the blastocyst cavity |
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Where does the yolk sac come from?
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- Blastocyst cavity
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How does the Amnion form?
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- Amnioblasts delaminate from the epiblast and form membrane surrounding amniotic cavity
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What two structures give rise to primary yolk sac?
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- Exocoelomic membrane
- Exocoelomic cavity **cells migrate from hypoblast to form membrane which surrounds blastocyst cavity which is now called exocoelomic cavity |
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What is extraembryonic mesoderm derived from and where is it located?
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- Derived from hypoblast
- Located around amnion and primary yolk sac |
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What is extraembryonic coelum derived from?
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- Isolated cavities in extraembryonic mesoderm
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What is the connecting stalk?
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- embryonic mesoderm attatches wall of amniotic cavity to trophoblast
- coelem does not develop here |
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What does connecting stalk give rise to?
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- Umbilical cord
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What two layers does the extraembryonic mesoderm form?
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- Somatopleuric extraembryonic mesoderm: lines trophoblast and outside of amniotic cavity
- Splanchno extraembryonic mesoderm: lines outside of yolk sac |
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When does Secondary yolk sac form?
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- As extraembryonic coleom forms
- Primary yolk sac decreases in size - Exocoelmic vescicle is degenerates (remnant) |
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What forms the chorion?
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- Extraembryonic somatic mesoderm
- Trophoblast **coleom now called chorionic cavity |
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What are predisposing factors of ectopic pregnancy?
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- Previous history of PID/Salpingitis
(pelvic inflammatory disease/inflammation of fallopian tubes) - Previous surgery on tubes or close to tubes - Previous history of ectopic pregnancy - Intra Uterine Device - Advanced maternal age - Smoking |
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What is gastrulation?
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- Process by which the bilaminar disc is converted to trilaminar disc
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What are two places where the mesoderm does not reach?
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- Prochordal plate (cranium)
- Chrodal reion (cloacal membrane) |
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What is primitive streak?
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- Thickened linear band formed by migrating cells of epiblast at beginning of 3rd week
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Where is primitive streak located?
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- Caudal end of embryo
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What does primitive streak grow to form?
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- Primitive node at its cranial end
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What does prochordal cavity form in the future?
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- mouth
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What does cloacal membrane form in the future?
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- anus
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How does intraembryonic mesoderm form?
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- Cells from primitive migrate between epiblast and hypoblast
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How does intraembryonic mesoderm form?
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- Displaced cells migrated from hypoblast
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When does the primitive streak degenerate and what does it become?
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- around 4th week and beomes insignifican structure of sacrococcygeal region
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What happens if primitive streak persists?
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- Becomes sacrococcygeal teratoma
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What is and how does the notochordal process form?
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- A median cellular cord that is formed by cells which have migrated cranially from the primitive node
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Where is the notochord located?
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- Extends from primitive node to prochordal plate
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What is the prochordal plate?
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- Where endoderm and ectoderm fuse
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What are the two regions on the embryo where the disc is bilaminar?
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- Prochordal plate: forms oropharyngeal membrane
- Cloacal membrane: site of future anus |
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What defines primitive axis of the embryo?
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- The notochord- gives rigidity
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What does the notochord give rise to?
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- Vertebral column
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How does Neurenteric Canal form?
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- The primitive pit extends into notochordal process.
- Cells of process fuses with endoderm. - Located between yolk sac and primitive cavity **if persistence occurs, then have neurenteric cysts |
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What is allantois?
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- Outpouching from yolk sac extending into connecting stalk
- Occurs around day 16 - Involved w/ development of urinary bladder as it will form urachus |
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What is neurulation?
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- Processes involved in formation of neural tube
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What does the neural tube give rise to?
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- Brain and spinal cord
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When is neurulation complete?
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- end of 4th week
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How does neuroectoderm form?
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- notochord induces overlying ectoderm
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How does neural groove form?
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- Neural plate invaginates in longitudinal plane
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Where are folds of neural groove prominent?
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- Cranial region
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How does neural tube form?
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- Neural folds move towards each other and begin to fuse converting neural plate to neural tube
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What are neuropores?
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- Openings at cranial and caudal end of neural tube
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When is neuralation complete?
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- During 4th week when neuropores close
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What happens if two openings of neural tube do not fuse?
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- Severe malformations of the brain
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What are neural crest cells?
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- Specialized cells at surface ectoderm and neuroectoderm
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What happens to neural crest cells when neural tube is formed?
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- Separate into two parts and migrate ventrolaterally
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What are dervitives of neural crest cells?
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1) Dorsal root ganglia and ganglia of ANS
2) Schwann cells 3) Piamater and arachnoid 4) Melanocytes 5) Adrenal medulla 6) Skeletal and muscular components of the head |
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What three parts is the intraembryonic mesoderm divided into along sides of the notochord and neural tube?
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1) Paraxial mesoderm
2) Intermediate mesoderm 3) Lateral plate mesoderm |
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What are somites?
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- Balls of paraxial mesoderm on either side of the neural tube
- Give rise to axial skeleton and associated musculature |
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What are chordomas?
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- Tumors of notochordal remnants in bone
- Arise anywhere in skeleton from base of skull to coccyx |
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What are neural tube defects?
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- occur due to defect in neurulation
- common birth defects |
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What causes neural tube defects?
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- Multifactoral: genetic and environmental
- Folate deficiency - Chromosomal abnormality (Trisomy 13, 18. 21) - Maternal hyperthermia - Maternal diabetes - Alcohol abuse - Drugs like valproate (anti epileptic) |
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What should pregnant women take to prevent neural tube defects?
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- Folic acid
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What is raschischisis?
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- Failure of fusion of vertebral arches and neural tube with consequent exposure of neural tissue
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What is cranioschisis?
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- Congenital failure of skull to close usually accompanied by defect in development of the brain
- Associated with anencephaly |
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What is anencephaly?
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- Defect in closure of neural tube during fetal development.
- Marked defective development of the brain together with absence of brain and spinal cord |
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What is meningocele?
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- Only meninges are protruding
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What is meningomyelocele?
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- Brain and spinal cord are protruding out of body
|
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What is decidua?
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- Phase after implantation of endometrium
- Under influence of progesterone - Decidual cells derived from connective tissue cells which have increased glycogen and lipid content |
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What layer of deciduas gives rise to placenta?
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- Deciduas basalis
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What is the chorion made up of?
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- Trophoblast
- extraembryonic mesoderm |
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What is Chorion Laeve?
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- Chorionic villi associated w/ deciduas capsularis disappears and leave a bare area known as Chorionic leave
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What is Chorion Frondosum?
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- Chorionic villi associated with deciduas basalis will develop further to form placenta
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What is Primary Chorionic Villi?
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- Cytotrophoblast plus synchotrophoblast
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What is secondary chorionic villi?
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Cytotrophoblast plus syncytiotrophoblast plus extraembryonic mesoderm
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When does the cytotrophoblastic layer gradually start disappearing?
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- As placenta ages
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What is cytotrophoblastic shell?
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- Area where tertiary villi invades layer between syncytiotrophoblast and decidua
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Where do maternal blood vessels empty?
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- Intervillous space of cytotrophoblastic shell
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When does growth of placenta continue until/completely form?
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- 20th week of gestation
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What is the fetal component of the placenta?
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- Chorionic villi
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What is the maternal component?
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- Chorionic villi
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What is the maternal component?
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- Decidua basalis
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What is placenta divided by?
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- Placenta septa (composed of villi) that project toward chorionic plate
- Placenta divided into cotyledons - Maternal cotyledons form placenta |
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What is placenta membrane?
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- Separates maternal and fetal blood
- Composed of: 1) endothelium of fetal blood vessels 2) Connective tissue of villus 3)Cytotrophoblast 4)Syncytiotrophoblast - After 20th week, placenta has formed, membrane is smaller, allowing more gas exchange |
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What is the function of the placenta?
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- Metabolism-synthesizes glycogen, cholesterol, and fatty acids that serve as energy sources for fetus
- Transport: - Oxygen, CO2 - Vitamins, glucose - Steroid hormones (not proteins) - Electrolytes - IgG antibody - Drugs - Infection agents - Small amount of blood - Endocrine: - HCG - Human chorionic sommatomammotropin - Human chorionic tyrotropin - Human chorionic adreno-corticotropin - Progesterone and estrogen |
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Where is HCG produced?
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- placenta
|
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When is HCG detectable in blood or urine?
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- 1-2 days after implantation
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When do HCG reach a peak?
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- 8-10 weeks of gestation
|
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What is the function of HCG?
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- Stimulates corpus luteum and maintains pregnancy
- Forms basis of urine pregnancy test |
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What gives rise to the umbilical cord?
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- Connecting stalk
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What is the umbilical cord covered by?
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- Amnion
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Which vein of the umbilical cord degenerates?
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- Right umbilical vein
|
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What forms Wharton’s Jelly?
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- Extraembryonic mesoderm
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What is the umbilical cord a remnant of?
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- Yolk sac
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What composes the fetal membrane?
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- Fused amnion and chorion along with deciduas
|
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What is amniotic fluid?
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- Clear yellowish fluid present in the amniotic sac covering the fetus
|
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What is the major contribution to amniotic fluid?
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- Urine from the fetus
|
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How is amniotic fluid circulated?
|
- Exchange through amniochorionic membrane
- Amniotic fluid swallowed by fetus and is absorbed in respiratory and digestive tracts |
|
What is oligohydraminos?
|
- Decrease in amniotic fluid
- Due to excessive swallowing of amniotic fluid, carried away in blood from placenta and discharged |
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What is polyhydraminos?
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- Increase in amniotic fluid
- Could be due to problem w/ swallowing |
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What is pulmonary hypoplasia?
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- If too little amniotic fluid, lungs will not develop
|
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What is the function of amniotic fluid?
|
- Shock absorption
- Freedom of movement - Promotes symmetrical growth of fetus - Maintains constant temperature around fetus - Barrier for infection - Normal lung development |
|
What is amniocentesis?
|
- Amniocentesis is a common prenatal test in which a small sample of the amniotic fluid surrounding the fetus is removed and examined.
- Do not perform before 14 weeks of pregnancy b/c not enough amniotic fluid |
|
What is chorionic villus biopsy?
|
- Take biopsy of chorionic villus from vagina round 8-10th week of pregnancy
- 10th week is better - procedure performed to see if there is an abnormality in fetus |