Cerebellar gross anatomy of the african grasscutter (Thryonomys swinderianus-temminck, 1827) during foetal and postnatal development

Abstract

In Nigeria, the African grasscutter (Thryonomys swinderianus) is bred as a mini-livestock, and research model. This study provides some information on the ontogeny of its cerebellum through gross observations of external cerebellar features from foetuses on foetal days 60 and 90, neonates on postnatal day 3, juveniles on postnatal day 72 and adults on postnatal day 450. On foetal day 60, the cerebellum was a smooth, semi-circular mass, devoid of folia or sulci; cerebellar lobes and vermal lobules were not present. On foetal day 90, the vermis was distinct, but vermal lobules were indistinct. On postnatal day 3, the cerebellar cortex was convoluted with the folia and fissures of grossly distinct lobes. The cerebellar vermis was divided into all the lobules typical of mammalian vermis; while the lingula, central lobule, culmen and declive were on the cerebellar dorsum, the folium, tuber, pyramis, uvula and nodulus were caudally located. The culmen was undivided and the crus rostralis was unpaired. On postnatal day 72, the pre-central fissure was deeper than that observed on postnatal day 3; the culmen was divided into the pars rostralis and pars caudalis; the crus rostralis was bifoliated by a fissural line. On postnatal day 450, the cerebellar fissures were deeper than before; the vermal and hemispheric lobules were better delineated. The bifoliation of the crus rostralis was more evident. The intra-crural fissure was very distinct and referred to as the great horizontal fissure. The results of the present study will add to the data base of rodent neuroanatomy, necessary for teaching and research.