Question

What is the cortical and acrosomal reaction?

Answer 1

Capacitation:

1. The physiological modifications that spermatozoa must go through in order to be able to penetrate and fertilize an egg are referred to as sperm capacitation.
2. This improves sperm motility (hyperactivity), meaning sperm is more likely to reach the egg (in the oviduct)

Cortical reaction:

1. After fertilization, an exocytotic calcium-dependent process occurs which is referred to as cortical response.
2. The cortical response, which prevents polyspermia—the union of several sperm with one egg—is a mechanism brought on by the release of cortical granules from the egg during fertilization.
3. This is characterized by the fusion of cortical granules with the egg's plasma membrane.
4. It releases the contents of secretory granules into the perivitelline region to prevent polyspermic fertilization.

Acrosomal reaction:

1. After sperm capacitation, an exocytotic response known as the acrosome reaction is brought on by a Ca⁺⁺ influx.
2. It is crucial to the process of fertilization because it allows spermatozoa to pass through the zona and fuse with the plasma membrane of the egg.

The steps are represented below: