Select the letter of the choice that best completes the statement. The gland that governs the production of lymphoid cells is thea. thymus.b. thyroid.c. parathyroid.d. pituitary.
Select the letter of the choice that best completes the statement. The gland that governs the production of lymphoid cells is the
a. thymus.
b. thyroid.
c. parathyroid.
d. pituitary.
Introduction:
The lymphoreticular system comprises various types of cells as listed below:
- Structural cells: Endothelial cells, reticulum cells, and fibroblasts.
- Immunologically competent cells: Lymphocytes, plasma cells, and macrophages.
In the circulating blood, approximately 70 percent of lymphocytes are T lymphocytes, 20 percent are B lymphocytes, and 10 percent are null cells.
Correct option:
- Option (a) is correct.
Explanation:
-
The prime function of the thymus is the production of the thymic lymphocytes. It is the major site for the proliferation of lymphocytes in the body. At the time of maturation, the lymphocytes gain new surface antigens (Thy antigens) and are referred to as T lymphocytes or T cells (thymus-dependent). Unlike in the peripheral organs, the proliferation of lymphocytes in the thymus is not dependent on antigenic stimulation. The thymus is responsible for conferring immunological competence on these cells when these cells are present in the thymus. Most proliferative lymphocytes die in the thymus, and only about a percent migrate to the peripheral lymphoid organs. These T cells are present in the blood circulation and lymphatics of human beings. The T cells are responsible for cell-mediated immunity.
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