Question

The mammal who has no scrotum and testis lie in abdominal cavity is
A)Bat
B)Dog
C)Elephant
D)None of the above

Answer 1

Hint: The large group of mammals that includes humans, Boreoeutherian land mammals, have externalised testes. At temperatures lower than their core body temperature, their experiments perform best. Their testicles are situated outside the body, suspended inside the scrotum by the spermatic cord.

Complete answer:
In mammals, a derived characteristic is monotremes with descended testes and Afrotheria (including elephants) both retain the ancestral state of character.These may be ascrotal or scrotal for those mammals with downward testicles. It is hypothesised that testicular descent occurred within Mammalia only once with the ascrotal Laurasiatheria. Cetaceans, phocid whales, hippos, tapirs, rhinos, and some bats are present in descending ascrotal testes.

The scrotum controls and retains the test temperature at 35 degrees Celsius (95 degrees Fahrenheit), i.e. 2 or 3 degrees below the temperature of the body at 37 degrees Celsius (98.6 degrees Fahrenheit). Depending on the ambient temperature, temperature control is affected by the smooth muscles of the scrotum pushing the testicles either closer to or further away from the abdomen.Higher temperatures influence spermatogenesis.

Animals that travel at a constant rate have internal testicles and no scrotum, such as elephants, whales, and marsupial moles. Unlike placental mammals, while there are many marsupial species without an external scrotum, some male marsupials have a scrotum that is anterior to the penis, which is not homologous to the scrotum of placental mammals. In humans, during intercourse, the scrotum can provide some friction, helping to improve the action.

Hence, the correct answer is option (C)

Note: There may be added benefits of having the scrotum and testicles located outside the abdominal cavity. Abdominal pressure does not affect the external scrotum. This may prevent the testicles from emptying until the sperm has been sufficiently matured for fertilisation. Another benefit is that it protects the experiments from jolts and compressions related to an active lifestyle.