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12 Cards in this Set
- Front
- Back
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Hypothalamus |
LH and FSH in pituatitary Produces GNRH which stimulate secreation of |
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3 phases of endometrial cycle |
Menstrual phase Proliferative phase (follicular phase) --> FSH stimulates the ovarian follicle to produce estrogen Ovulation - Day 14 of the endometrial cycle An estrogen spike a few days prior to ovulation triggers a spike in LH (luteal surge)The luteal surge corresponds with the release of the matured oocyte Secretory phase (luteal phase) Corpus luteum begins producing progesterone Uterine wall becomes thicker during secretory phase If egg is not fertilized everything degrades and the cycle is repeated |
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Prevention of polyspermy |
Spermatocyte binds to zona pellucida Inhibits other sperm from entering oocyte Enzymes break down zona pellucida Attachment of sperm to ZP3 ZP3 binding --> Binding triggers zonal reaction Fast block Rapid electrical depolarization of plasma membrane within 2-3 second of fusion Short lived (last for 5 min) Won’t allow any other sperm cell to get into oocyte Slow block Involves Ca2 release from site of fusion Results in release of polysaccharides |
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Early stages of development: from egg to blastula |
Meiosis is arrested in the egg prior to fertilization by the spermatozoa Fertilization leads to the presence of maternal and paternal pronuclei within the egg Meiosis now proceeds Series of rapid cell divisions takes place Total cell size remains the same Zona pelucida prevents the early embryo from attaching to side of maternal reproductive system Prevents ectopic implantation Once zona pelucida disappears allows attachment to uterus wal |
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Process of implantation |
Mature follicle Ovulation Fertilization Cleavage (1 day)(2 days) Morula (2.5-3 days) (8 Cells)-16 Blastocyst (4 days) hatches from the zona pelucida Implantation (6 days) |
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Cleavage |
Consists of repeated mitotic divisions of zygote → results in increased cell number In humans cleavage is a slow 6 days process as zygote moves through uterine tube Blastomere = refers to each cell of divided zygote |
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Blastocyst “hatches” |
the process of getting rid of zona pellucida; now sticky |
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Epiblast cells → become |
ectoderm Neural groove neural tube |
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Mesoblast cells |
become paraxial mesoderm and intermediate mesoderm |
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Hypoblast |
will be replaced by cells migrating out of primitive streak Cells that replace hypoblast cells form the endoderm |
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Notochord |
Rod-like structure located underneath the neural tube A structure that is present only during embryogenesis Structure regresses during development Notochord secretes factors important for embyrogenesis The neural fold will eventually form the spine on the dorsal aspect of the embryo |
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Weismann’s theory of nuclear determinants |
Weismann assumed that there were factors in the nucleus that were distributed asymmetrically to daughter cells during cleavage and directed their future development Roux’s experiment to investigate Weismann’s theory of mosaic development Mosaic mechanism: cells have their character and fate determined at each cleavageExperimentU sed a fertilized frog egg Assumed that if each half of the 2-cell stage embryo is different, killing one half (blastomere) should still allow the other half to developResults Showed that the undestroyed half of the embryo developed normally Supports mosaic model of development in frogs |
