Human T lymphocyte (T cell), coloured scanning electron micrograph (SEM). Lymphocytes are involved in the specific immune response and are composed mainly of precursor T cells and B cells (pre-T cells and pre-B cells). Pre-T cells and pre-B cells are subsets of lymphocytes that originate in the red bone marrow from hematopoietic stem cells. Pre-T cells circulate in the blood before migrating to the thymus where they develop into specialized cells (helper T cells and killer T cells) that are able to identify antigens and infected tissue. Magnification: x2,600 when shortest axis printed at 25 millimetres.
Model release not required. Property release not required.