Neonatal Nurse Practitioner Practice Exam

T lymphocytes, or T cells, originate from hematopoietic stem cells in the bone marrow. However, their development and differentiation into mature T cells occur primarily in the thymus. During this critical process, T cells undergo several stages, including positive and negative selection, which ensure that they acquire the ability to recognize foreign antigens while remaining tolerant to self-antigens. This selection process is essential for a functional and self-tolerant immune system, as T cells that fail to pass these stages undergo apoptosis (programmed cell death).

While the bone marrow is responsible for the initial production of T cell precursors, it is within the thymus that these precursors gain their functional characteristics, including the expression of specific surface markers like CD4 or CD8, which ultimately determine their role in the immune response. The lymph nodes and spleen play crucial roles in the immune response and the activation of T cells once they have matured, but they do not participate in the development and differentiation process itself.