Reticular cells are fibroblast-like cells that synthesize reticular fibers. They are stellate in shape. Elongated cytoplasmic processes of these cells wrap around the bundles of reticular fibers, effectively isolating these structural components from the parenchma of the lymphatic tissue and organs. Besides their supporting role, they express surface molecules and produce substances that attract T cells, B cells and dendritic cells.
Reticular cells have been subdivided on the basis of their location and phenotype into 3 major subsets: fibroblastic reticular cells, dendritic reticulum cells and interdigitating reticulum cells.
Fibroblastic reticulum cells have many ultrastructural characteristics of fibroblasts but differ from them in containing prominent bundles of microfilaments and in reacting strongly with antibodies to smooth muscle type myosin and actin.
Dendritic reticulum cells are present in lymph follicules of lymph nodes, spleen, and tonsils. These antigen presenting cells are characterized by numerous cytoplasmic processes extending (dendrits) between adjacent lymphoid cells. Dendritic retikulum cells are known as a key cell of the germinal center microenvironment. These cells acquire and maintain antigen-antibody complexes and can stimulate memory B cells that can, in turn, stimulate further T cell activity.
Interdigitating reticulum cells are arachnoid nonlymphoid accessory cells found in the T-cell areas of peripheral lymphoid tissue. They are potent antigen-presenting cells responsible for initiating primary T-lymphocyte immune responses
Six types of epithelial reticular cells were observed in thymus: type I (subcapsular-perivascular), type II (pale), type III (intermediate), type IV (dark), type V (undifferentiated) and type VI (large-medullary).
In this review, the microscopic and functional characteristics of reticulum cells are summarized.
Key Words: Antigenic Stimulation; Lenfoid Tissue; Reticulum Cells.
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