Macroscopic organization of the cerebellum of the African giant pouched rat (Cricetomys gambianus - Waterhouse, 1840)

The degree of folding or foliation and its functional implication is one of the major difference in the cerebellar cortex of rodents. The enlargement / reduction of individual lobules is thought to account for their specific behavioural differences. The macroscopic anatomy of the cerebellum in ten mature African Giant pouched rats (AGPR) is detailed here for the first time. The results showed that the division of the cerebellum in this species followed the same general pattern of having three lobes (anterior, posterior and flocculonodular) lobes. Also on the ventral aspect, three cerebellar peduncles that connected the cerebellum to the brain stem were observed. The lobule VI and its principal lateral continuation corresponds to the lobulus simplex. The lateral extension of lobule VII corresponds to the well developed lobulus ansiformis, consisting of Crus I (crus rostrale), Crus II (crus caudale) and the anterior part of the lobulus paramedianus. The largest lobule in the anterior lobe is lobule V and it is subfoliated into Va, Vb, Vc and Vd by small fissures, while the smallest lobule is lobule I, which is not sublobulated. As for the posterior lobe, lobules VI and IX are the broadest and are sublobulated into five and three sublobules, respectively. Lobule X is subfoliated into two lobules, Xa and Xb, and it was observed to be the smallest of the posterior lobes. The primary fissure was the deepest and most prominent fissure, followed by the precuminate fissure, while the precentral fissure was the smallest. In conclusion, the well-developed ansiform lobe of Crus I and Crus II in AGPRs may help in the excellent climbing strategies and the manipulative use of the forelimbs in grasping objects.