Question

The diagram shown below is the longitudinal section of a testis of man. Study it carefully and answer the questions that follow:
State the functions of the parts labeled 1 and 3 in the diagram.

Answer 1

Hint: Testis is the reproductive gonad of male which acts as the site for the production of male gametes that is called spermatozoa. It is present in pairs and is covered in a muscular pouch-like structure called scrotum.

Complete Answer:
- Tests are present in male exclusively which is homologous to the female ovary. The main function of testis is to produce both sperm and androgens like testosterone.
- Testes are covered in a scrotum which is the outer muscular sac like structure in which testes are present. Within the scrotum, testicles are present which is comprises of several parts like:
- Seminiferous tubules
- Epididymis comprises caput epididymis, corpus epididymis and cauda epididymis.
- Vas deferens

In the given diagram, the labelling is:
1. Scrotum
2. Vas deferens
3. Epididymis

- The function of 1 i.e. scrotum is to cover the testicles inside it. Scrotum is present outside the body that helps in providing temperature 1-2°C lower than the normal body temperature that is suitable for the production of spermatozoa.
- Scrotum is generally present outside the body in which testicles are present. In species, testicles are present inside the body for their whole life like in elephants while in some species, it descends down in scrotum after the birth like in rats. If the testicles are unable to descent down in the scrotum then it is known as cryptorchidism. In this condition the males are sterile.
- The function of 3 i.e. epididymis is to collect and store the produced spermatozoa. At this site the spermatozoa resides for days to weeks until the ejaculation takes place. Apart from it, this site is responsible for the maturation of the spermatozoa.

Note: Seminiferous tubule is the primary site where the production of spermatozoa takes place. The production is regulated by the hormone, follicle stimulating hormone (FSH) i.e. released from the anterior pituitary gland.
There are other cells also present inside the seminiferous tubules like sustentacular cells also called as sertoli cells that act as a nurse cells and provide nutrition to the produced spermatozoa. Leydig cells are also present that are responsible for the production of testosterone.