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29 Cards in this Set
- Front
- Back
What happens to the oocytes when a woman hits puberty? |
The oocyte which was arrested at prophase 1 will now complete meiosis 1 around ovulation and then arrest at metaphase of meiosis2. |
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What happens to the secondary oocyte after fertilization? |
fertilization will trigger the completion of meiosis 2 which results in a mature oocyte |
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Factors that contribute to non-disjunction |
1. error in spindle fiber attachment 2. defect in synapsis and maintenance of cross-overs 3. defect in cohesion of sister chromatids 4. oocytes lack effective spindle tensional checkpoint |
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nondisjunction |
anything that causes incorrect sorting of chromosomes during meiosis or mitosis |
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What's the difference between getting nondisjunction in meiosis 1 vs meiosis 2 |
nondisjunction in meiosis 1 will results in none of the gametes having the correct number of chromosomes. in meiosis 2 nondisjunction will cause 2 cells to be aneuploidy while the other 2 gametes will be normal |
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4 ways to diagnose aneuploidy before the birth of the baby |
1. Aminocentesis (14-16weeks) 2. Chorionic villus - placental sampling (10-12 weeks) 3. Maternal blood testing for fetal cells (early as 6 weeks) -limited info 4. Pre-implantation genetic screening in IVF lab
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twin formed from splitting of zygote |
monozygotic, dichorionic, diamniotic |
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twins formed from complete splitting of inner cell mass |
monozygotic, monochorionic, diamniotic |
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twins formed from two eggs ovulated and fertilized separately |
dizygotic/fraternal, dichorionic, diamniotic |
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twins formed from incomplete splitting of inner cell mass |
monozygotic, monochorionic, monoamniotic |
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twins formed from late separation |
conjoined twins, monozygotic, monoamniotic |
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What's a possible hazard of monochorionic twins? |
growth disparities due to unequal placental circulations |
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What's a possible hazard of monoamniotic |
tangled/knotted umbilical cord |
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differentiation of spermatid to sperm |
mitochondria --flagellum golgi -- acrosome condensation of nucleus excess cytoplasm discarded |
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through what mechanism do MOST autosomal aneuploidies rise from |
nondisjunction in female meiosis 1 |
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What problem arises for sperm with age? |
as men age they have a higher chance of a mutation in their spermatogonia which would lead to autosomal dominant de novo mutations |
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3 functions of zona pellucida |
1. sperm binding site (this triggers acrosome reaction) 2. block to polyspermy via cortical reaction 3. prevent premature/ectopic implantation |
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Sperm capacitation |
sperm is normally coated with cholesterol/glycoproteins until it sheds that coat by vaginal secretions. Ca++ influx leads to hyper-activation of sperm motility |
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Main events of fusing of sperm and egg |
-cortical reaction -egg completes meiosis II -egg nucleus decondenses (pronucleus) -fusion of egg and sperm pronuclei --> zygote |
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Cleavage division steps |
blastomeres > morula >(compaction) blastocyst > inner cell mass |
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What happens when you get implantation close to the cervix? |
placenta previa |
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when the trophoblast comes into contact with the endometrium it differentiates into these two layers |
invasive syncytiotrophoblast internal cytotrophoblast |
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What are the roles of syncytiotrophoblast? |
1. Secretes enzyme to degrade uterine wall to pull in the blastocyst 2. secretes hCG (detected in urine/blood for pregnancy test) |
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How does the endometrium respond to trophoblast invasion? (3 things) |
1. Decidual reaction of stromal cells -- they accumulate glycogen and lipids and will be engulfed by the trophoblast to nourish the embryo 2. Angiogenesis 3. Gland secretion (all used to nourish embryo) |
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What are lacunar spaces? |
internal membrane channels in syncytiotrophoblast which allows mixing of maternal blood and secretion (uteroplacental circulation) |
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What are the problems with ectopic pregnancy |
most ectopic pregnancies occur in the fallopian tube so there isn't enough space for the fetus to develop and the tissues of the fallopian tube are unable to form stable vessels |
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The epiblast gives rise to the germ layers while the hypoblast contributes to |
yolk sac lining |
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How is the amniotic cavity (sac) formed? |
fluid secretion by aminoblasts |
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What are the three cell types/layer that are part of the chorion? |
1. syncytiotrophoblast 2. cytotrophoblast 3. extraembryonic mesoderm |