Microglia and microglia-derived brain macrophages in culture: generation from axotomized rat facial nuclei, identification and characterization in vitro.

In order to study microglial cells and microglia-derived brain macrophages in vitro, a method has been developed which allows the transfer of mitotic microglial cells from adult rat brain into tissue culture. The studies were performed on facial motor nuclei which were explanted after axotomy of the facial nerve. Outgrowing cells were identified and characterized by (i) morphological criteria using light and electron microscopy, (ii) in vivo [3H]thymidine labeling combined with subsequent in vitro autoradiography, (iii) immunocytochemistry for vimentin, GFAP, Fc and complement receptors, MHC antigens, laminin, fibronectin, factor VIII related- and 04 antigen as well as lectin histochemistry, and (iv) functional in vitro tests. In addition, a microglial cell line was established from proliferating cells. The results indicate that perineuronal microglia rather than astrocytes, perivascular cells, oligodendrocytes or endothelial cells may become phagocytic after having been activated by axotomy in situ.