BIOL303 Lecture Notes - Lecture 12: Zona Pellucida, Tight Junction, Ectopic Pregnancy
15 Dec 2013
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Document Summary
Zygotic genome is used for cleavage and early development and these events do require maternal transcripts and proteins. It is the process where the loose blastomeres express e-cadherin and become tightly packed. The individual blastomeres are no longer as obvious and the morula take on a smoothened look. The first differentiation is cells becoming either inner cell mass or trophoblast/trophoectoderm. Totipotency refers to the earliest blastomeres that can become either inner cell mass or trophoblast cells. Pluripotency refers to the inner cell mass cells that can become any cell type in body, but not trophoblast: sketch and label a picture of a typical blastocyst. Cavitation forms the blastocoel, it involves trophoblast cells secreting fluid into the morula. The zona pellucida allows for sperm binding during fertilization and prevents the blastocyst from sticking to the oviduct walls preventing ectopic pregnancy. The blastocyst is able to attach to the endometrium because of the presence of the trophoblast.
