Morphology of the Digestive Apparatus in Oligoryzomys nigripes (Rodentia, Sigmodontinae)

Although the Genus Oryzomys is widely distributed in the Americas, there are very few published data on the morphology of this rodent group. Notably, in relation to the digestive apparatus, the data are sparse and fragmented. In addition, because rodents are important animal models, this information may be useful in recent and promising areas for applied studies, such as clinical, therapeutic, and surgical models. Here, we describe the morphological characteristics of the digestive system in Oligoryzomys nigripes using gross morphology and light and scanning electron microscopy. In total, five specimens were used. After an incision from the oral to pelvic cavities, all organs of the digestive system were exposed and dissected. Next, all structures from the oral cavity, pharynx, esophagus, stomach, intestines, liver, and pancreas were processed and evaluated by microscopy. The results revealed that the digestive system of O. nigripes consisted of an oral cavity, in which the tongue, minor and major salivary glands, and dental arch were predominant. Behind the oral cavity, the pharynx, esophagus, stomach, intestines, liver, and pancreas were identified and presented typical morphological characteristics of rodents. In conclusion, our results suggest that the morphology of the O. nigripes digestive system differs from the previously described data for other rodent species, mainly due to the absence of the molar teeth and gallbladder in this species.