Lymphoid Tissue and MALT: Structure, Functions, and Classification of Lymphoid Organs

Lymphoid Tissue

Question 1. What is lymphoid tissue? List its main functions.
Answer.

The lymphoid tissue is a kind of specialized connective tissue. It is made up of a meshwork of reticular cells and reticular fibers (supporting framework) and a large number of lymphocytes occupying the spaces within the meshwork. The other cells present in the lymphatic tissue are plasma cells and macrophages.

Lymphoid Tissue Function Defence of the body

Note: The lymphoid tissue mainly consists of lymphocytes and macrophages, which protect the body against the invasion of microorganisms, for example, bacteria and viruses by producing specific immune responses.

Classify lymphoid organs. The lymphoid organs are classified into the following two types:

• Primary lymphoid organs, e.g. bone marrow and thymus
• Secondary lymphoid organs, e.g. lymph nodes and spleen

Mucosa Associated Lymphoid Tissues

Question 1. Write a short note on ‘MALT’.
Answer.

The term MALT stands for mucosa-associated lymphoid tissue. It consists of noncapsulated, dense lymphatic nodules, or follicles formed by the aggregation of lymphocytes in the submucosa of gastrointestinal (GALT) and respiratory tracts (BALT).

MALT Function

The MALT provides immunological protection against invasion of the body by microorganisms, e.g. bacteria and viruses via vulnerably exposed absorptive surfaces of the gastrointestinal and respiratory tracts.

Question 2. Enumerate MALT associated with the gut (alimentary canal).
Answer.

The MALT associated with the gut includes:

• Tonsils
• Aggregated lymphoid nodules (Peyer’s patches)
• Aggregations lymphoid follicles in vermiform appendix
• Solitary nodules in the oesophagus, small intestine and large intestine.