Rat cerebellar cells in tissue culture. II. Immunocytochemical identification of replicating cells in astrocyte-enriched cultures.

Astrocyte-enriched monolayer cultures were obtained by growing cells dissociated from 8-day-old rat cerebella pretreated with hydroxyurea. After 7 days in vitro a carpet of flat polygonal cells was obtained. The identity of these flat cells was established and their numbers quantified using immunological markers for astrocytes, fibroblasts and endothelial cells (antisera against fibrillary acidic protein and Thy-1, and Chagasic sera respectively). A combination of (3H] thymidine autoradiography and immunocytochemistry showed extensive replication of astrocytes, the number of which rose from about 20 to 80% of the total cells during the 1st week in vitro: 80% of these cells were labelled at 7 days after exposure to thymidine on the 1st day in culture. The culture conditions chosen did not support the survival of nerve cells. and fibroblasts constituted 5-7% of the cells at 7-14 DIV, whilst the total cell number remained roughly constant. On the other hand, staining with a new specific marker for endothelial cells revealed that these cells divided actively, ultimately accounting for the majority of the non-astrocytic cells.