Morphometric Study of Synapses in the Rat Cerebellar Cortex in Their Early Postnatal Periods

Han, Hoo Jae

Abstract

Early postnatal period is considered as the critical period for formation and maturation of the synapses. And cerebellum has the major role in the development of equilibrium and somatic motor function, especially in the early postnatal age. So, I performed this study to investigate the morphological changes of the synapses in the rat cerebellar cortex. Sprague-Dawley rats were used as experimental animals. The ultrastructure of Synapses was observed in six groups ; 3-day, 1-week, 2-week, 3-week, 4-week, 5-week. The results are as followes. 1. After birth, the synaptic density was increased gradually by the forth week. 2. The length of postsynaptic densities was increased significantly in the period between first and second week. 3. There was significant correlation between the length of postsynaptic densities and the area of synaptic vesicle clusters. 4. The frequency of asymmetric and/or frown synapses was increased dramatically with advancing ages. According to the above results, the synaptogenesis in the rat cerebellum is very active in their early postnatal periods. And asymmetric and/or active frown synapses were the major type of synapses with advancing ages.