Please cite as Berridge, M.J. (2011) Cell Signalling Biology; doi:10.1042/csb0001008
Fertilization of a mammalian oocyte.
Module 8: Figure mammalian fertilization (animated)
The process of fertilization depends on a sequence of carefully orchestrated events: 1. Sperm motility and chemotaxis directs the spermatozoon towards the oocyte. 2. The spermatozoon makes contact with the zona pellucida and undergoes the acrosome reaction, during which the release of hydrolytic enzymes opens up a pathway towards the oocyte plasma membrane. 3. During contact and fusion with the oocyte plasma membrane, phospholipase Cζ (PLCζ) is injected into the nucleus and begins to form inositol 1,4,5-trisphosphate (InsP3
) that triggers Ca2+
oscillations. 4. The sperm-induced Ca2+
oscillations induce chromosome separation (see Module 9: Figure chromosome separation
for details of the mechanism). 5. The sperm-induced Ca2+
oscillations are also responsible for oocyte activation that results in cell proliferation. 6. The sperm nucleus (N) moves into the oocyte.