Birth weight and development of cerebellar cortex.

Postnatal development of the cerebellar cortex in the mouse is characterised by proliferation of cells of the external granular cell layer, migration of the granule cells across the molecular layer and simultaneous maturation of the Purkinje cells. At the same time, there is elaboration of the folia and fissures of the cerebellum. These features were studied postnatally in relation to the age and weight of the animal in the inbred strain of C3HeB/FeJ mice fed on standard diet. In every litter there was a difference in body weight of the various pups, and for the present study, the lowest and highest weighing animals from each litter were used. The observations presented here are on animals at the 1st, 7th, 13th and 24th days postnatum. It appears that the size of the cerebellum and the degree of the development of the cerebellar cortex are directly proportional to the weight of the animal for that age period.