TRANSIENT EXPRESSION OF FGF-5 MESSENGER-RNA IN THE RAT CEREBELLAR CORTEX DURING POSTNATAL-DEVELOPMENT

Previously, we showed that fibroblast growth factor (FGF) receptor-4 m RNA was transiently expressed in proliferative granule cells of the ex ternal granule layer of the rat cerebellar cortex during early post-na tal development (A. Miyake rt al., Mol. Brain Res., 31 (1995) 95-100). In this study, we examined the expression of FGF-5 mRNA in the rat br ain during post-natal development by in situ hybridization. FGF-5 mRNA was transiently expressed in granule cells of the internal granule la yer of the cerebellar cortex during early post-natal development. The temporal sequence of FGF-5 mRNA expression was similar to that of FGFR -4 mRNA expression. As the proliferation of granule cells in the exter nal granule layer and their migration through the molecular layer into the internal granule layer actively occur during these periods, the p resent findings suggest that FGF-5 as well as FGFR-4 might play import ant roles in the proliferation and/or migration of granule cells durin g the post-natal development of the cerebellar cortex.