BIOL303 Lecture Notes - Lecture 1: Zona Pellucida, Inner Cell Mass, Ectopic Pregnancy
2 Apr 2018
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Development in mammals significantly more difficult due to: size of the human zygote; contains. 1/1000th the volume of a xenopus egg: number of eggs produced: much less than amphibians; < 10 eggs ovulated in any given instance. Internally the cells form gap junctions to allow molecules and ions to pass. Dependent upon adhesion molecules such as e-cadherin; which is the signal for cell aggregation. (a) is similar to the rotational change in sea. (b) rotational cleavage here is similar to c. elegans. Mammalian blastula called blastocyst (f) inner cell mass being formed here. The compacted 8 cell embryo divides to form the. They form the chorion, the embryonic portion of the placenta. The mouse embryo proper (= the actual embryo) is derived from cells at the center of the 32-cell- morula. These cells give rise to the inner cell mass (icm) which will develop into the embryo, but also into the extraembryonic membranes yolk sac, allantois and amnion.
