Morphology of the Oral Cavity of the African Giant Rat (cricetomys Gambianus, Waterhouse)

Ten adult African giant rats (AGR), 5 males and 5 females, were used to determine the regional anatomy of their oral cavity. Body measurements were recorded. The oral cavity was accessed by disarticulating the temporo-mandibular joint and the gross morphology of the lips, palate, cheek pouch, teeth, tongue and major salivary glands were studied. Morphometric parameters of the cheek pouch, tongue and major glands were also determined. Histological features of the tongue were demonstrated after haematoxylin and eosin staining. The upper lip revealed a philtrum extending from the median septum of the nostrils and terminating at the oral fissure in a divergent triangle to expose the elongated incisors. The lower lip formed a smooth arch ventral to the upper lip. Average number of palatine ridges was 9. The tongue (mean weight of 3.80±0.08 g) appeared spatula shaped. Main papillae were filiform and fungiform, with scattered vallate papillae on histology. The mean pouch capacity of males and females was 27.46±0.41 mL and 27.18±0.49 mL respectively while the dentition of the AGR was noted as 2(I1/1 C0/0 P0/0 M3/3) and showed typical rodent features. The major salivary glands (parotid and mandibular) were well developed. This work reports baseline research data on the anatomy of the AGR’s oral cavity and will have usefulness in determining the adaptive features in this rodent to its diet, habitat and lifestyle.