PHSI3010 Lecture Notes - Lecture 11: Zona Pellucida, Tight Junction Protein 1, Tight Junction
22 Mar 2019
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Document Summary
Describe stages of embryonic development from zygote to blastocyst. Embryo moves along oviduct uterus (6 days in human; 4. 5 days in mouse: oocyte zygote 2/4/8-cell morula blastocyst implantation. Special features of preimplantation stages: surrounded by zona pellucida. Prevents attachment to fallopian tube: reductive cell cycles. Increase in nucleo/cytoplasmic ratio: no transcription until 2-cell (mouse), 4-8 cell (human) Cells controlled at post-transcriptional level: cells spherical, uniform localization of proteins. Cells are totipotent (an immature stem cell; capable of giving rise to any cell type/a complete embryo) Describe first events of differentiation in preimplantation embryo. First differentiation occurs at 8-cell stage due to process of compaction. Localization of e-cadherin to regions of cell-cell contact. Tight junction formation separation of apical and basolateral domains: formation of tight junctions due to expression of zo-1, compaction leads to formation of 2 cell-types. Expression of na+-k+-atpase on basolateral surface leads to vectorial transport of electrolytes and water.
