An ultrastructural study of cortical remodeling in cytosine arabinoside induced granuloprival cerebellum in tissue culture.

Mouse-derived cerebellar explants were exposed for 5 days to cytosine arabinoside, an inhibitor of deoxyribonucleic acid synthesis. They were then maintained in normal nutrient medium until fixation for electron microscopy at 15-20 days in vitro. The cerebellar cortex lacked granule cells, but Purkinje cells, Golgi neurons and a few basket and stellate cells survived. Astrocytes and oligodendrocytes were diminished in number and myelination was absent. Purkinje cell recurrent axon collaterals increased in number and formed synapses with the surviving cortical neurons and their processes. The ultrastructural alterations that occurred in the cytosine arabinoside-treated cultures were consistent with an interpretation of cortical remodeling in which Purkinje cell axon collaterals were the dominant inhibitory elements.