On the development of the gigantocerebellum in the mormyrid fish Pollimyrus (Marcusenius) Isidori

Abstract

Breeding obtained in our laboratory has allowed us to analyse the development of the gigantocerebellum in the mormyrid fish Pollimyrus. Light microscopical observations of serial histological sections of embryos and larvae reveal that all parts of the cerebellum arise as in other teleosts from the dorsal rhombencephalic anlage and have a bilateral origin. The brain develops very rapidly: the corpus cerebelli ( c.cer) and associated cerebellar structures, i.e. eminentia granularis ( e.gr), lobus caudalis ( lc) and transitorius ( lt), lobi lineae lateralis ( lll), are formed in 40 days while the development of the valvula needs 180 days. The differentiation of the cerebellar cortex in these different structures follows at the same rhytmn but with a certain delay.