BIOL 3530 Lecture 4: Chapter 3.2
7 Oct 2016
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Document Summary
The three main stages of vertebrate development: setting up the main body axes (a/p and d/v, specification of three germ layers (endoderm, mesoderm and ectoderm, germ layer patterning (mesoderm and early nervous system) Maternal genes provide factors (rna and proteins) to the egg during oogenesis (including subcellular localization to specific regions. Zygotic genes are expressed by the embryo"s genes. Both maternal and zygotic genes may have long term effects upon the embryo"s development. Before fertilization, the clear distinction that the animal pole is different from the vegetal pole is established. Cleavage of the embryo divides the contents of the egg into distinct regions. 1st cleavage - parallel to (with) the axis (vertical division) 2nd cleavage - 90 to 1st cleavage (vertical division) 3rd cleavage - 90 to both above cleavages to separate the animal from the vegetal poles (horizontal division).
