Veterinary Histology and Embryology

RETICULO-ENDOTHELIAL SYSTEM

• This name is given to the system more on physiological and pathological consideration than on anatomical structure.
• The cells of this system do not form true endothelium. All highly phagocytic cells of the body, except leucocytes belong to this system.
• The only certain method of identification of these cells is by injection of nontoxic inert particulate matter like the carbon particles or Indian ink into the living animal.
• Injection of trypan blue or lithium carmine into living animal is called vital or intra-vital staining.
• The macrophages engulf the particulate matter like carbon particles. After vital staining the cells containing the dye are found in the cells in loose connective tissue in the reticular tissue or in the blood sinuses of certain organs.
• In the connective tissue they correspond to the histocytes.
• Kupffer cells of liver, reticular cells of lymph nodes, spleen and bone-marrow, cells lining the sinusoids of spleen and microglia cell of the nervous system are examples of this system.