Question

Which of the following areas in the lymph node is regarded as thymus-dependent and thymus-independent area?

• A. Medulla and paracortex region respectively
• B. Cortex and paracortical region respectively
• C. Medulla and cortex region respectively
• D. Paracortical and cortex region respectively

Answer 1

The correct option is D Paracortical and cortex region respectively

Lymphoid organs are specialized tissues that provide the microenvironment for the functional maturity (primary lymphoid organs) or activation (secondary lymphoid organs) of lymphocytes.

Lymph nodes are secondary lymphoid organs. They are encapsulated bean-shaped structures clustered at the junctions of lymphatic vessels.

Morphologically a lymph node is divided into three concentric regions as follows :

• Cortex - It is the outermost region populated mainly by B-cells, thus it is called the thymus-independent region.
• Paracortex - It is the middle region enriched largely by T-cells. Thus it is referred to as the thymus-dependent region. Hence option d is correct.
• Medulla - It is the inner region and contains large blood vessels, sinuses, and medullary cords. The medullary cords contain antibody-secreting plasma cells, B-cells, and macrophages.

Figure : Lymph node