The development of synaptic contacts in the cerebellum of Macaca mulatta.

Abstract

AbstractThe maturation of various cerebellar cortical cells, the appearance of afferent fibers to the cerebellum, and the development of synaptic contacts in the cerebellar cortex and deep nuclei was investigated in the fetal macaque. Ultrastructural studies were done on cerebellum obtained from fetuses at 75, 100, 125 and 150 days after conception to interrelate the temporal development of these three systems. At 75 days, synaptic contacts were seen on somas and axons of neurons in the deep cerebellar nuclei, and climbing fibers formed pericellular baskets around Purkinje cells. By 100 days the climbing fibers synapsed with somatic spines of the Purkinje cells, and mossy fiber endings were present in the internal granule cell layer. Synaptic contacts were also seen on dendritic processes of neurons in the deep cerebellar nuclei at this time. In the 125 day cerebellum, Golgi cells were identified for the first time and climbing fibers and parallel fibers made synaptic contact with both Purkinje and Golgi cells. At 150 days parallel fibers made synaptic contact with superficial stellate cells and mature cerebellar glomeruli had appeared. At this stage, axosomatic contacts of climbing fibers on the soma of Purkinje cells had disappeared. The relationship of these anatomical observations to possible functional activity is discussed.