OSMT (Ontario Society of Medical Technologists) Practice Exam

T cells become immunocompetent in the:

1. a. bone marrow

2. b. thymus

3. c. lymph nodes

4. d. b and c

The correct answer is: d. b and c

T cells undergo their development and maturation into immunocompetent cells primarily in the thymus. The thymus is a specialized organ where precursor cells migrate from the bone marrow and undergo a series of changes that lead to the formation of T cells, which are crucial components of the adaptive immune system. During their time in the thymus, T cells are subjected to positive and negative selection processes that ensure only functional and non-self-reactive cells enter the circulation. While the bone marrow is important for the initial generation of these precursor cells, it is specifically in the thymus that T cells gain their immunocompetence. The lymph nodes are sites of activation and proliferation of T cells after they have matured, but they do not play a role in the actual development and maturation process of T cells. Thus, while the bone marrow and lymph nodes serve critical roles in the immune system, it is the thymus that is the primary site of T cell maturation and immunocompetence, making it the correct focus in this question.