This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Ch.47: Animal Development 14/03/2008 01:54:00 1. List and describe the four major stages of embryonic development. Fertilization: the union of haploid gametes to produce a diploid zygote Cleavage: the process of cytokinesis in anima cells, characterized by pinching of the plasma membrane; also the succession of rapid cell divisions without growth during early embryonic development that converts the zygote into a ball of cells o By the end of cleavage, that embryo is a hollow ball of cells called a blastula o Blastocyst (for mammals instead of blastula) stem cells gastrulation: the formation of a gastrula (three-layered embryo) from a blastula organogenesis: the development of organ rudiments from the three germ layers o cellular differentiation-process by which a less specialized cell becomes more specialized 2. Describe two events that occur during fertilization. Fusion of maternal and paternal genomes o Acrosomal reaction: the discharge of sperms acrosome when the sperm approaches an egg Sperm releases hydrolytic enzymes into the zona pellucida (extracellular matrix of egg) which breaks it down and allows sperm to reach the plasma membrane of egg o Cortical reaction: exocytosis of enzymes from cortical granules in the egg...
View Full Document