• Occurs in the uterine tubes – Within a day of ovulation

• Spermatozoa cannot fertilize an ovum until after capacitation (rearrangement of mitochondria in sperm after ejaculation, increases motility)

Fertilization (conception)

Fertilization

Figure 29.1a

Fertilization

Figure 29.1b

• Oocyte is in meiosis II – Surrounded by the corona radiate

• Spermatozoa release hyaluronidase and acrosin– Enzymes required to penetrate corona radiate

• Single spermatozoan contacts oocyte, fertilization begins– Oocyte activation

The Oocyte at Ovulation

• Oocyte completes meiosis II– Functionally mature ovum– Female pronucleus and male pronucleus fuse

(amphimixis)

• Polyspermy prevented by membrane depolarization and cortical reaction

Oocyte activation