Question

Which of the following glands is prominent in the rat?
(A) Salivary gland
(B) Liver
(C) Thymus
(D) All of the above

Answer 1

Rats belong to the phylum Chordata of the animal kingdom, they are rodents. The anatomy and morphological structure of animals is dependent upon their habitat and its characteristic features. In rats, the prominent glands show separation into the cortex and medulla region.

Complete answer:
The thymus gland is prominent to the rats and is adherent to the roots of the large blood vessels and attached to the trachea. It doesn't vary in size much from newborn rat to an adult of 20 weeks or more. The thymus gland in rats shows separation into cortex and medulla and the reticulum differs from that of the atypical lymphoid gland as it consists of stellate, anastomosing, connective tissue cells but not trabeculae.
The salivary glands are found in the mouth of an organism and are exocrine glands that secrete saliva through a system of ducts. In humans, the number of these glands is three. In the case of other animals, these glands modify to produce proteins. The venom glands of venomous snakes, Gila monsters, and shrews are also modifications of these glands.
The liver is found in the case of vertebrates and is an important organ for digestion as well as detoxification of various metabolites and protein synthesis. Its structure varies in different species but mostly contributes to indigestion and protein synthesis.
The thymus is another specialized lymphoid organ of the immune system where lymphocytes or T cells mature. It is located in the upper part of the chest in the case of humans. It is present in almost all jawed vertebrates.

So, the correct answer is ‘Thymus gland’.

Note:
Rats have prominent thymus glands as well as salivary glands with a similar structure as humans. Both humans and rats have 3 types of salivary glands namely parotid, submandibular and sublingual which secrete serous, mucous, or mixed saliva via proper ducts. On the other hand, the thymus glands in rats play important roles in the immune reaction of the organism.