Cross Studies of the Pons and Medulla Oblongata of the African Striped Ground Squirrel (Xerus erythropus)

Abstract

African striped ground squirrels (Xerus erythropus) are commonly consumed small mammals (bush meat) by rural dwellers as protein supplement. This study was aimed at providing information on the gross morphology of the brain of twenty (20) African striped ground squirrel-Xerus erythropus (10 males and 10 females), with an average bodyweight and body length of 481.60 ±21.55g and 43.84±0.53cm respectively. Each squirrel was euthanized using ketamine hydrochloride at 80mg/kg body weight, thereafter perfused with neutral buffered formal saline and then the brains were extracted by craniotomy. The dorsal view of the whole brain revealed that the two cerebral hemispheres were distinctly divided by longitudinal fissure and separated from the cerebellum by a transverse fissure. The pons was small and curved to form a triangular shape dorsally and widened out to form a convex shape ventrally. The medulla oblongata was conical (funnel shape) in shape. Dorsally, the medulla oblongata is divided into open and closed medulla. Other structures typical of the mammalian medulla oblongata’s dorsal surface such as, cuneate fasciculus, dorsal intermediate sulcus, lateral furniculus and dorsal lateral sulcus were not visible. The trapezoid body (covered by olivary bodies), which was medially divided into equal halves by the ventral median fissure, was the most prominent feature ventrally. The present study shows that the cerebellum of the African Striped ground squirrel covered only the rostral part of the myelencephalon represented by the 4th ventricle. The results of this study can be used for comparative neuroanatomical studies and for the clinical diagnosis of brainstem disorders.