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34 Cards in this Set
- Front
- Back
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Where does fertilization of the gametes occur? |
Uterine tube of female |
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What is a zygote? |
first cell formed by fertilization (egg and sperm) |
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What is cleavage? |
series of mitotic divisions that increase number of cells while reducing size |
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After 30 hours, The zygote divides into... |
two daughter cells (blastomeres) |
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BY 3rd day, what forms? |
Morula = solid all of cells |
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What forms after five days of cleavage? |
hollow ball of cells and differentiation of cells occurs |
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What is the outer layer of cells called in Blastocyst? |
Trophoblast |
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Inner cavity called? |
Blastocoele |
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Inner cell mass called? |
Embryoblast |
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What will the embryoblast form? |
Embryo (proper) and contribute to form extraembryonic membranes |
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The blastocyst must implant in the _______ of the uterine wall about 7 days after fertilization |
Endometrium |
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What happens when trophoblast is in contact with uterine wall? |
Transform into syncytiotrophoblast (TO Burrow into endometrium so blastocyst will be embedded within) |
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What does the syncytiotropholast begin developing? |
Extensions - Villi (to increase surface area) |
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What is amniotic cavity? |
after 9 days fertilization, embryoblast separates from trophoblast = space |
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What forms two flattened layers of cells? |
Blastodisc (bilaminar germinal disc) |
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What is gastrulation? |
migration of cells in blastodisc to give rise to 3 distinct layers of cells |
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What are the primary germ layers? |
Ectoderm Mesoderm Endoderm |
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What do each germ layer form? |
Ectoderm = epidermis of skin and nervous tissue Mesoderm = all muscle and connective tissue Endoderm = lining of viscera |
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What is the fxn of yolk sac? |
help transport nutrients and begin production of blood cells and blood vessel formation |
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What is amnion? |
membrane around amniotic cavity encloses amniotic fluid
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What is the fxn of amniotic fluid? |
helps cushion developing embryo |
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What makes up the chorion? |
trophoblast and part of mesoderm |
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Chorion will form what part of embryonic embryo? |
Placenta - disk shaped organ containing tissues from both embryo and endometrium (mother) |
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What is the fxn of Umbilical cord? |
transport nutrients, gases, and wastes between mother and embryo |
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What is the fxn of placenta? |
provides large surface area for materials to diffuse Embryo's blood protect embryo from mother's immune system |
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What is neurulation? |
Week 3-4, nervous system begins to develop from dorsal ectoderm. formation of Neural Tube |
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What happens at organogenesis? |
By 8th week, end of embryonic period, all major organs and systems have developed. |
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What is a fetus? |
embryo at beginning of the fourth month |
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What is implantation? |
blastula embeds in uterine wall |
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Allantois? |
outpocket of endoderm forms part of umbilical cord |
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Yolk sac |
forms blood cells and part of umbilical cord |
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What is a blastocyst? |
hollow ball of cells
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At what point does an embryo become a fetus? |
8 weeks |
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During what period is a miscarriage most likely? What may cause it? |
First 3 months Imbalance immune system, stress, first pregnancy with a boy |
