Art-labeling Activity: Structure of a Lymph Node (Close-up View of Cortex
The Correct Answer and Explanation is:
In the structure of a lymph node, the cortex is the outer region, located beneath the capsule. It is essential in the filtering of lymph, a fluid that circulates through the lymphatic system. The cortex consists of two main components: the outer cortex and the deep cortex.
- Outer Cortex: The outer part of the cortex primarily consists of follicles, which are spherical clusters of immune cells, notably B lymphocytes. These B cells play a crucial role in producing antibodies that help fight off infections. Within the follicles, some areas may have a specialized structure called germinal centers, which are regions where B cells proliferate and differentiate in response to pathogens.
- Deep Cortex: The deeper part of the cortex is also known as the paracortex and is primarily populated by T lymphocytes. T cells are essential for cellular immunity, assisting in the direct attack on infected cells or the regulation of other immune cells. The paracortex lies between the outer cortex and the inner medulla of the lymph node.
The cortex is rich in dendritic cells, which play a vital role in capturing and presenting antigens to T cells, helping trigger immune responses. Additionally, macrophages are scattered throughout the cortex, where they help filter out pathogens and debris from the lymph fluid.
Blood vessels, called high endothelial venules (HEVs), also penetrate the cortex. These specialized vessels allow lymphocytes to enter the lymph node from the bloodstream, facilitating their immune surveillance function.
Thus, the cortex of a lymph node is a vital site for immune cell activation and response, serving as a first line of defense against infections by processing lymph and initiating immune reactions.
