Question

Write a short note on capacitation.

Answer 1

• Capacitation is the final maturation process that sperm undergo in the female reproductive tract.
• It enables sperm to gain the ability to fertilize the ovum.
• During capacitation, calcium ions enter the sperm, increasing tail motility from gentle to whip-like movement.
• The acrosomal membrane is lost, exposing enzymes like hyaluronidase which help sperm penetrate the follicle cells (corona radiata) surrounding the ovum.
• Hyaluronidase also dissolves the zona pellucida at the sperm entry point.
• Capacitation includes a compatibility check between sperm antifertilizin and ovum fertilizin, ensuring species-specific fertilization.
• Once a sperm penetrates the ovum, the zona pellucida changes chemically to prevent entry of other sperm (zona reaction), maintaining monospermy.
• Capacitation is essential for successful fertilization and the initiation of further events leading to embryo formation.