Gross Morphology of the Cerebrum and Brainstem of the Adult African Grasscutter (Thryonomys Swinderianus—Temminck, 1827)

In order to meet the increasing protein and income demand in Africa due to the rapid population growth, wildlife, such as the African grasscutter, is currently bred and domesticated as microlivestock. This study is one of the series on the brain morphology of this very large rodent, aimed at providing information that is lacking in the literature. Here, the gross anatomy of the cerebrum and brainstem in nine adult African grasscutters is described. The cerebral cortex was smooth, devoid of gyri and sulci, thus, placing the rodent in the lissencephalic group of mammals. However, blood vessels on the cortex created arterial and venous impressions. The cortex was asymmetrically-tapered oval in shape. The rostral and caudal colliculi were exposed through the cerebral transverse fissure. The rostro-caudal extent of the corpus callosum was from the mid-point of the frontal and parietal lobes, to a point just rostral to the occipital lobe. The rostral colliculi were grossly smaller than the caudal colliculi. The occulomotor and trochlear nerves emerged from the ventral midbrain, rostral to the pons. The pons was exceptionally large; it was pre-trigeminal. On either side of the ventral median fissure of the medulla oblongata were conspicuous pyramids. The trapezoid bodies were also conspicuous. These, and other findings, will be useful in future phylogenetic comparison of rodent brain morphology.