The primary lymphoid Organs
Bone Marrow
T and B lineage cells both arise from a subset of
hematopoietic stem cells (HSC) in the bone marrow or fetal live that become committed
to the lymphoid pathway of development. Human B lymphocyte development take
place entirely within the bone marrow. T cells on other hand develop from immature
precursor that leave the bone marrow and travel through the blood stream to the
thymus, where they proliferate and differentiate into mature T – lymphocytes.
Thymus
The thymus is consists of thymic stromal cells and
thymocytes. The fully developed thymus consists of two lobes, each comprising
multiple lobes. Thymus is the primary site at which T lymphocytes develop and
become functionally competent.