Experimental modifications of postnatal differentiation and fate of glial cells related to axo‐glial relationships

Abstract

The fate of glial cell lines following Wallerian degeneration in the rat optic nerve was analysed after pulse labelling with [3H]thymidine. The rats were unilaterally enucleated at the key stages 2, 5, 8 and 20 days after birth. Three hours later, they were injected intraperitoneally with [3H]thymidine and killed after 1, 3, 5, 10 and 20 days survival. Oligodendrocytes were the most affected, being unable to differentiate after 2 days enucleation, dying rapidly or transforming into another cell type after 5, 8 and 20 days enucleation. The apparent stability of the astrocyte population is due to an equilibrium between increased differentiation from glioblasts and increased death, the latter being preponderant at the key stage 2 days. Finally, the steady increase in the number of microglia may be due to the transformation from other cells, either glioblasts for the early time intervals or oligodendrocytes later on. It appears, then, that the interrelation between glial cell lines during differentiation is more intricate than previously suspected and is closely dependent, for each line, upon the integrity of axons.