Title: Lymphoblast (spleen, rat)
Description: Electron microscopy.
Interspersed between small lymphocytes the lymphoblast with a high nucleus-cytoplasm ratio is a larger cell with a distinct nucleolus. The cytoplasm is studded with numerous polysomes and ribosomes, only few mitochondria and a single strand of rough endoplasmic reticulum are present.
Background: A lymphoid progenitor cell divides to produce two types of lymphoid stem cells. One type migrates to the thymus, proliferates and differentiates into T lymphocytes. The other type remains in the bone marrow or settles in the spleen and lymph nodes where it proliferates into lymphoblasts that in turn divide and eventually become immunocompetent B lymphocytes (in follicles). Dependent on the appropriate stimulation the latter cells might differentiate via plasmablasts into plasma cells.
Keywords/Mesh: blood, bone marrow, lymphoblast, histology, electron microscopy, POJA collection