Question

In which of the following mammals, testes remain in the abdomen?
A. Human
B. Elephant
C. Rabbit
D. Ox

Answer 1

Mammals are the most successful and the most dominant animals today. They are hairy animals, the females of which have milk producing mammary glands to suckle their young ones. There are about 4000 species of mammals. Human beings are also mammals. Sexes are separate with sexual dimorphism. Tests are usually descended into scrotal sacs in adults. They are also warm blooded.

Complete answer:
A pair of testes is situated in the abdominal cavity in the sac of skin called the scrotum or scrotal sac. Testes are the primary sex organ. Scrotum keeps the testes at a temperature 2-2.5ᵒC lower than the internal body temperature, which is necessary for the synthesis of sperms. Each testes is oval in shape, measuring about 4-5 cm in length and 2-3 cm in width. The outer covering of the testis is formed by a dense fibrous membrane called tunica albuginea. Now, consider all the options.
In humans the testis present outside the abdominal cavity because they have the sacs of skin called the scrotum.
In elephants the testis remains in the abdomen because they do not have the sacs of skin called Scrotum .
In rabbits the testes are present outside the body in the pouch of skin called scrotum or we say extra-abdominal at the age of 2.3 to 3 months because spermatogenesis requires lower temperature.
In ox, the testis is present outside the abdominal because the scrotum provides a cooler temperature than the body for the formation of spermatozoa.

So, the correct answer is “Option B”.

Note:
Spermatogenesis is the process of formation of spermatozoa or sperms from diploid spermatogonia. It is initiated at the age of puberty by the gonadotropin releasing hormone secreted by the hypothalamus.
The increased level of GnRH stimulates the anterior pituitary which then secretes follicle stimulating hormone and luteinizing hormone.