Neuroglia of the developing optic nerve in the course of Wallerian degeneration

Unilateral enucleation was performed in 8 days rabbits and morphological changes occurring in the degenerating immature optic nerve were evaluated by means of light and electron microscopy and correlated with histoenzymatic changes in the activity of various phosphatases, esterases and oxidoreductases. The results of these experiments have lead to the following conclusions: 1. In contrast to the marked hyperplasia of the astroglia, the cellularity of the neuroglia of the oligodendroglial line suffered a considerable decrease in the course of Wallerian degeneration of the immature optic nerve. 2. Disconnection of axons from their parental perikaryons caused a considerable delay and reduction of differentiation of the immature neuroglia cells into oligodendrocytes. 3. The histoenzymatic pattern of neuroglia in the immature degenerating optic nerve differs from and bears no relation to that of the normally developing nerve. 4. Cells of the oligodendroglia line, when maturing in contact with degenerating axons are incapable of promoting myelinogenesis. 5. The genetic information contained in both the immature and mature oligodendroglia cells is not the sole factor safeguarding the transformation of these cells into myelinating ones.