Lecture 25

Lecture 25 - Lecture #25: Development I FIGURE 47-3 I)...

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Lecture #25: Development I FIGURE 47-3 I) Fertilization a. Sperm Structure (FIGURE 46-12d): acrosomal vesicle (digestive enzyme), nucleus (chromatins), mitochondria, flagellum (swimming) b. Egg: Surface Elements i. Jelly coat, villeline layer + plasma membrane = viteline envelope, cortical granules (enzyme) c. Acrosomal Reaction (sea urchin) i. Sperm contacts jelly coat exocytosis of acrosomal enzyme penetrate jelly coat ii. Acrosomal process binds to vitelline layer Bindin on sperm will beind to bindin receptors on vitelline layer formation of Fertilization Cone with plasma membranme of the egg iii. Membranes fuse sperm nucleus enters egg cyctoplasm iv. Gamete fusion sodium entry (slow action potential, depolarization) blocks subsequent sperm entry “FAST BLOCK TO POLYSPERMY” which occurs < 1 sec lasts ~ 1 min. d. Cortical Reaction i. Depolarization Calcium release from internal stores into cytoplasm ii. Increase calcium cortical granules exocytose enzymes
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Lecture 25 - Lecture #25: Development I FIGURE 47-3 I)...

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