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Related Flashcards
Cards In This Set
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Cortical Reaction
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A release of calcium ions that occurs when sperm penetrates egg; causes depolarization of ovum membrane, preventing other sperm from fertilizing & also increasing the metabolic rate of the newly formed diploid zygote
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Fertilization Membrane
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The depolarized & impenetrable membrane of a zygote that occurs after the cortical reaction
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Fraternal (Dizygotic) Twins
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Occur when 2 eggs both get fertilized & implanted
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Identical (Monozygotic) Twins
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Occur when the same egg splits in half to make 2 identical eggs
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Cleavage
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The early divisions of cells in the embryo.Results in a large number of smaller cells, because the volume of the embryo doesn't change at this time.
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Indeterminate Cleavage
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Results in cells that are capable of becoming any cell in an organism, or a whole organism
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Determinate Cleavage
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Results in cells that are committed to differentiating into a specific cell type
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Morula (Mulberry)
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Solid mass of cells seen in early development
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Blastula
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Has fluid-filled center called blastocoel & 2 different cell types:
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Chorion
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Created by trophoblasts, gives rise to placenta
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Chorionic Villi
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Formed by trophoblasts, microscopic projections that penetrate endometrium & support maternal-fetal gas exchange
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Umbilical Cord
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Embryo is connected to placenta by this, consists of 2 arteries (that carry deoxygenated blood away from baby heart) & 1 vein (that carries oxygenated blood to baby heart)
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Yolk Sac
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Embryo is supported by this until the placenta is functional, eventually becomes the umbilical cord
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Allantois
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Connects the embryo to the yolk sac, eventually becomes the umbilical cord
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Amnion
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Thin, tough membrane filled with amniotic fluid, serving as shock absorber during pregnancy
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