Question

In mammals, testes occur within the scrotal sacs outside the viscera because of the
A. Presence of urinary bladder
B. Presence of rectum
C. Long vas deferens
D. Requirement of lower temperature for spermatogenesis

Answer 1

Hint: Testes are the male gonads situated in scrotum, a pouch of pigment skin arising from the lower abdominal wall. It lies below the pubic symphysis in front of the upper part of thigh and below the penis.

Complete answer:
• Testes are soft, smooth, pinkish oval organs about 4.5 cm long, 2.5cm wide and 3 cm thick.
• The scrotal sac is divided into two compartments in order to hold one testicle in each.
• Scrotum protects testes and acts as thermo-regulator i.e. it regulates temperature for proper functioning of testis. The testes require a temperature 2-3 degree C less than the body temperature for the production of sperms which can not be achieved within the body hence they are located outside the abdominal cavity.
• The wall of scrotum is made up of smooth muscles called dartos tunic muscles which helps in temperature regulation within the scrotal sac by contracting and relaxing. Each testes is connected to the wall of scrotum by a short fibromuscular band called gubernaculum.
• This lower temperature of 2-3 degree C is necessary for production of viable sperms.

Hence, the correct answer is option (D).

Additional information:
Function of testes:
• It is responsible for production and storage of viable male gametes called sperm or spermatozoa
• It is also responsible for the synthesis and secretion of male sex hormone called testosterone.

Note: Some important points to remember:
• Testes develop in the lumbar region high in the abdominal cavity just below the kidney.
• During 7th month they descend into the scrotal sac through the inguinal canal.
• Failure of descent of testes on one or both sides in a newborn from abdomen into scrotum leads to sterility called cryptorchidism.