Electron microscopic study on the synaptic glomeruli of rat cerebellum: quantitative and qualitative analyses using...

The synaptic glomeruli of rat cerebellum (cerebellar glomeruli) were studied at postnatal ages of 1 to 7, 9, and 15 days in the attempt to formulate qualitative and quantitative analyses for the synaptic junctional development. Ethanol-phosphotungustic acid (E-PTA) was used to stain the synapses. The synaptic junctions, composed of dense projection, intercleft density, and postsynaptic band in synaptic glomeruli were first observed at a postnatal age of 6 days and more than three synaptic junctions were not recognized in this stage. Three types of synaptic junctions, symmetrical, asymmetrical immature, and asymmetrical well-developed, were recognized according to advancing postnatal age. Although each postnatal stage had different ratios among the three types, the number increases with postnatal age. These results suggest that the synaptic glomeruli are already functional by the eye-opening stage.