Question:

What happens during fertilization in humans after many sperms reach close to the ovum

Updated On: May 1, 2024
  • Cells of corona radiata trap all the sperms except one
  • Only two sperms nearest the ovum penetrate zona pellucida
  • Secretions of acrosome helps one sperm enter cytoplasm of ovum through zona pellucida
  • All sperms except the one nearest to the ovum lose their tails
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The Correct Option is C

Solution and Explanation

The process of fusion of a sperm with an ovum is called fertilization. During fertilization, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of additional sperms. Thus, it ensures that only one sperm can fertilize an ovum. The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. In contact with the surface of egg covering, the acrosome releases its contained hydrolytic enzymes, also called sperm lysins. It is known as acrosomal reaction. Acrosome reaction results in dissolving of corona cells and degeneration of zona pellucida which helps in sperm penetration.
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Concepts Used:

Human Reproduction

Reproduction in human beings involves the fusion of male and female gametes that produces in their reproductive system.

Male Reproductive System:

The male reproductive system comprises:

  • Testicles (testes): A pair of oval-shaped organs masked in a pouch known as the scrotum. They manage the production of sperms and the male hormone testosterone.
  • Scrotum: It is a sac-like organ that hangs under the penis and behind it. It is the house of the testes, or testicles, and maintains a temperature that is needed for the production of sperm by it.
  • Vas deferens: The sperms produced in testes are stored in a tube known as the epididymis. Here the sperms get matured and pass to the urethra via the muscular tube known as vas deferens.
  • Accessory glands: This includes three glands, namely the prostate gland, seminal vesicles, and Cowper’s gland. The secretions from the mentioned three glands mix to form a fluid known as semen. Semen nourishes the sperm, raises the volume, and helps in lubrication.
  • Penis: The penis is a cylindrical tube that serves as both an excretory organ, and a reproductive organ. It transfers sperms into the vagina during sexual intercourse.

Female Reproductive System:

The female reproductive system is active before, during, and after fertilization as well. It comprises the following parts:

  • A pair of ovaries: A pair of ovaries produce and stores ovum in them. They also produce a female hormone known to be estrogen.
  • Fallopian tubes (Oviducts): They are the area of fertilization. They connect both the ovaries with the uterus.
  • Uterus: Uterus is the place of development for the embryo.
  • Vagina: The part that connects the cervix to the external female body parts is called a vagina. It is the passage for the penis during coitus as well as a fetus during transfer.