In vivo and in vitro differentiation of neurons and astrocytes in the rat embryo : immunofluorescence study with neurofilament and glial filament antisera

Antisera raised against neurofilament (NF) peptides and glial fibrillary acidic protein (GFA) (subunit of glial filaments) have been used to identify neurons and astrocytes in order to study their development and differentiation in rat embryo. In vivo observations showed that NF-positive cells first appeared in 12-day-old embryos, whereas GFA-positive cells appeared in brain and spinal cord on the 18th day. In vitro observations showed that NF-positive cells could be obtained only in cultures from 12-day embryos onwards. The further differentiation of neurons involved neurite elongation, aggregation of cell bodies to form islets, and emergence of very brightly staining prominent neurons with large cell bodies and long neurites which took part in complicate pattern formation. GFA-positive cells appeared in vitro on the 16th day and they could be observed even in cultures obtained from 10-day-old embryos. As the culture aged, the GFA staining became highly fibrillary. There was no physical interaction between neuronal and glial processes