Exploring the ventricles of an African rodent species: A morphological comparison in adult and juvenile Thryonomys swinderianus (African grasscutter)

Abstract

The neuroanatomy of a unique mammalian species, the Thryonomys swinderianus (African grasscutter or greater cane rat, GCR), offers invaluable information about its behavioural adaptations and evolutionary development. The ventricular system plays a crucial role in providing overall maintenance and protection to the brain by producing cerebrospinal fluid by the choroid plexus present in the individual ventricles. This study explored the morphological differences between the ventricles of adult and juvenile GCRs. Eight GCRs were procured, and the brains were extracted to assess for morphological features (brain weights), histological features, stereological characteristics (volume estimation) and immunohistochemical features (glial fibrillary acidic protein and ionized calcium binding adapter molecule, IBA-1 immunostains) of the ventricles. The adults' GCRs revealed higher mean values for brain weights (p > 0.05) compared to the juveniles. Histologically, there were similarities in the position of the individual ventricles with the presence of choroid plexus across age groups. At higher magnification, there were moderate differences in the lining of the ventricles by ependymal cells; the juvenile lining appeared denser compared to that of adults. The adults' aqueductal lumen appeared wider compared to their juvenile counterparts. Stereologically, the ventricular (lateral and fourth) volume revealed higher values for the adult compared to the juvenile, especially (p < 0.05) within the fourth ventricle. Ventricular immunoreactive cells (astrocytes and microglia) were observed to be more distributed in the adult than in their juvenile counterparts. This study revealed similarities and differences in the morphological characteristics of the ventricles between adult and juvenile GCRs.