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Human Zygote to Blastocyst Development (day 1 to 6) zona pellucid still intact (division occurs within the ZP).cell division becomes slower (centre cells, larger) and faster in peripheral cells.cell division is initially synchronous, then asynchronously.special "embryonic" cell cycle S phases and M phases alternate without any intervening G1 or G2 phases (MSMSMSMS, adult MG1SG2) therefore individual cell volume decreases.cleavage of zygote forms 2 blastomeres and is also cleavage with no cytoplasm synthesis.
#Dr najeeb lectures embryology movie
Links: Fertilization | Carnegie stage 1Ĭlick Here to play on mobile device | Mouse Zygote Movie page Pronuclear Fusion and Parental Genomes MoviesĬonceptus - the term refers to all material derived from this fertilised zygote, includes both the embryo and the non-embryonic tissues (placenta, fetal membranes). sperm contributes centriole which organizes mitotic spindle.male and female pronuclei, 2 nuclei approach each other and nuclear membranes break down.zygote ( Carnegie stage 1) is the first diploid cell formed following fertilisation.forms second polar body (a third polar body may be formed by meiotic division of the first polar body).Meiosis 2 - completion of 2nd meiotic division.enzyme alters ZP3 so it will no longer bind sperm plasma membrane.How the cortical reaction in a mouse egg is thought to prevent additional sperm from entering the egg Cortical Reaction - IP3 pathway elevates intracellular Calcium, exocytosis of cortical granules MBoC - Figure 20-32.
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Membrane Depolarization - caused by sperm membrane fusion, primary block to polyspermy.Membrane Fusion - between spermatozoa and oocyte, allows spermatozoa nuclei passage into oocyte cytoplasm.enzymes to digest the zona pellucida, exposes sperm surface proteins to bind ZP2.
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The acrosome reaction that occurs when a mammalian sperm fertilizes an egg