Sea Urchin Embryology Back to Contents page






The sperm enters and binds to the egg surface. This induces a calcium wave that causes the cortical granules, white, to fuse with the plasma membrane, releasing their contents and causing the fertilization membrane to rise. The sperm is then pulled into the egg where it moves to the egg nucleus and fuses. DNA synthesis occurs along with duplication of the centrosome, black. Nuclear envelope breakdown and chromosome condensation leads to the metaphase plate. Anaphase leads to telophase and cell division. The process is repeated.
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© 1997 Chris Patton, Stanford University