Observations on the lateral geniculate nucleus of the monkey (Macaca fascicularis) after eye removal: a light and...

The light and electron microscopic morphology of non-neuronal elements within the lateral geniculate nucleus has been studied in normal monkeys and after enucleation. In the normal lateral geniculate nucleus it is possible to find light and dark astrocytes; light, medium and dark oligodendrocytes; microglia, and the so-called "third" glial element of VAUGHN and PETERS (1968). Two types of perivascular elements are also present. After enucleation, the first overt response is an oedematous reaction in the denervated regions, without concomitant disruption of the capillary endothelium. The oedema seems to be connected with swelling and disruption of astroglia. After the first days of enucleation, the microglia disappear and are replaced by phagocytic glia (WONG-RILEY, 1972). From the presence of intermediate stages at characteristic sites within the nucleus, it is concluded that phagocytic glia develop from the same precursor as the "third" glial elements and that they are both immature forms of microglial cells.