Question

Capacitation refers to changes in the

• A. sperm after fertilization
• B. ovum after fertilization
• C. ovum before fertilization
• D. sperm before fertilization

Answer 1

The correct option is D

sperm before fertilization

The correct option is D.

Explanation of the correct option:

1. The phenomenon of sperm activation for fertilization in mammals is known as capacitation. It occurs before the fertilization process.
2. Capacitation is a biochemical process that occurs in the female reproductive tract.
3. Before fertilization, some secretion of the female reproductive tract removes the coating substances on the surface of sperms that are in the acrosome, after removal, the acrosomal site is active and sperm becomes active to penetrate the egg and then fertilization occurs.
4. The capacitation process takes 5 to 6 hours to complete.

Explanation of the incorrect option:

Option A:

1. During ejaculation, thousands of sperms enter through the vagina, but only a single sperm fertilizes the egg and after fertilization, the fertilized egg is implanted in the uterus.
2. Other sperms simply discharge from the body through the vaginal opening.

Option B:

1. After fertilization, the ovum starts dividing within 24 hours and moves into the fallopian tube, and stays for 3 to 4 days for maturation by division.
2. After the formation of the blastocyst, it implants in the uterus.

Option C:

1. Before fertilization, the ovum is first released in the fallopian tube during ovulation.
2. Then the ovum stays in the fallopian tube for about 24 hours to meet with the sperm to fertilize it.

Final answer: Capacitation refers to changes in sperm before fertilization.