Question

Given below is a diagram of the lateral section of the testis of a man. Study the same and answer the questions which follow.

1. Label the parts numbered 1 to 4 in the diagram.
2. State the functions of the parts labeled 1 and 3.
3. What is the significance of the testes being located in the scrotal sac outside the abdomen?
4. What is the role played by the inguinal canal?
5. What is semen?

Answer 1

1) Labeling the diagram

1. The testis is divided into multiple compartments called seminiferous lobules. It comprises seminiferous tubules.
2. Seminiferous tubules are housed in seminiferous lobules. It is the site of spermatogenesis or production of spermatozoa from the germinal epithelium.
3. The epididymis is a highly coiled tube present above the testis. It temporarily stores the sperms and exhibits peristalsis.
4. Vas Deferens or sperm ducts are long and thick muscular tubes that help in the transportation of sperms from the testes to the urogenital duct.

2) Functions of parts 1 and 3

1. Seminiferous lobules (part -1) consist of 1 to 4 coiled seminiferous tubules. It acts as a site of spermatogenesis, or the production of spermatozoa from the germinal epithelium.
2. It also comprises sertoli cells and leydig cells that nurse the spermatozoa for differentiation and production of testosterone respectively.
3. The epididymis (part-3) is the place of the conjunction of Vasa efferentia from the lobules. It is a highly coiled tube that temporarily stores sperms.
4. It consists of cells secreting glycoprotein that help in the nourishment, maturation, and motility of the sperm.

3) Location of testes

1. A pair of testes are located in a loose chamber that hangs down from the abdomen and is present in between the thighs. This is called the scrotum.
2. The scrotum helps in thermoregulation thus maintaining the temperature of 2°C lower than the body temperature. This helps in maintaining a proper environment for the production of sperms.
3. The dartos muscles help in the proper positioning of the testes in the scrotum based on the external climatic conditions.

4) Inguinal canal

1. The inguinal canal acts as a muscular passageway between the external genitalia and the abdominal cavity.
2. In males, it comprises the sperm ducts, nerves, blood vessels, and lymphatics.
3. It also helps in the descent of the testes just before birth.

5) Semen

1. Semen is an alkaline, viscous, and milky fluid produced by the male reproductive system.
2. It consists of sperms, proteins, chemicals, and fructose.
3. It also consists of certain prostaglandins that help in the survival and movement of sperms in the female reproductive tract.