The Use of Markers to Study the Regulation of Glial Cells in the PNS and CNS

Abstract

The main glial cells of the PNS and CNS can be identified both in situ and in culture by the use of combinations of different antibodies which act as markers for the different cell types. The particular combination of antibodies chosen depends very much on the developmental stage and anatomical area of the nervous system chosen, on whether the cells are being studied in situ or in culture, and on the question that is being asked. In studies of glia from the CNS antibodies have been particularly useful in identifying different glial types in dissociated cell cultures derived from various brain regions. These cultures normally contain a mixture of cell types, including neurons, unless special efforts are made to separate them, and although with practice some of the cell types can be identified on the basis of morphology, in many cases cells lose their typical in vivo shape, flatten and become more amorphous when grown on the flat surface of a glass coverslip or tissue culture dish. Thus a prime use of markers has been for identification (Mirsky, 1980). Astrocytes have most often been identified by the expression of glial fibrillary acidic protein (GFAP), although other markers such as glutamine synthetase are occasionally used. All astrocytes in culture appear to express high levels of GFAP. Many astrocytes in situ, particularly the fibrous astrocytes of white matter can also be labelled with antibodies to GFAP in tissue sections. In the cortex, however, many grey matter astrocytes are poorly labelled with GFAP antibodies. After lesion, GFAP expression is extremely strong in reactive astrocytes in tissue sections.