Lecture 20, Ch. 47

Lecture 20, Ch. 47 - Gastrulation ◆ Gastrula ~ 2 layered...

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Lecture #20 Date ________ Chapter 47 ~ Animal Development
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Embryonic development/fertilization Preformation ~ until 18th century; miniature infant in sperm or egg At fertilization/conception : Acrosomal reaction ~ hydrolytic enzyme action on egg jelly coat…. Fast block to polyspermy ~ membrane depolarization prevents multiple fertilizations…. Cortical reaction ~ release of calcium causes hardening of egg outer layer and creates a. .. Slow block to polyspermy and. .. Egg activation ~ increases metabolic activity; protein synthesis
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Blastomeres~ resultant cells of cleavage/mitosis Yolk ~ nutrients stored in the egg Vegetal pole ~ side of egg with high yolk concentration Animal pole ~ side of egg with low yolk concentration Morula~ solid ball of cells Blastocoel ~fluid-filled cavity in morula Blastula ~hollow ball stage of development
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Cleavage QuickTimeᆰ and a Cinepak decompressor are needed to see this picture.
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Unformatted text preview: Gastrulation ◆ Gastrula ~ 2 layered, cup-shaped embryonic stage ◆ 3 Embryonic germ layers: ◆ Ectoderm~ outer layer; epidermis; nervous system , etc. ◆ Endoderm ~ inner layer; digestive tract and associated organs; respiratory, etc. ◆ Mesoderm ~skeletal; muscular; excretory, etc. ◆ Invagination ~ gastrula buckling process to create the. .. ◆ Archenteron ~ primitive gut ◆ Blastopore ~ open end of archenteron Organogenesis: organ formation ◆ Blastodisc ~ cap of cells on top of yolk ◆ Primitive streak ~ invagination of blastodisc ◆ Neural tube ~ beginning of spinal cord ◆ Somites~ vertebrae and skeletal muscles ◆ Neural crest ~ bones and muscles of skull Amniote embryos ◆ Extraembryonic membranes : •yolk sac (support; circulatory function) •amnion (fluid-filled sac; protection) •chorion (placenta formation) •allantois (nitrogenous waste)...
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Lecture 20, Ch. 47 - Gastrulation ◆ Gastrula ~ 2 layered...

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