Morphometry of cryopreserved organs from the gastrointestinal system of squirrel monkeys (Saimiri sciureus, Linnaeus, 1758) for improvement of management

Abstract

Background: Nonhuman primates (NHPs) are fundamental for countless types of research and their phylogenetic similarities with humans make them valuable biomodels. Saimiri (squirrel monkeys) is the New World simian genus that is most widely used in research; however, little is known about the morphology of the gastrointestinal tract (GIT) of these animals.

Methods: The morphological and topographical aspects of GIT organs from 14 previously frozen carcasses of captive squirrel monkeys (Saimiri sciureus) were described as a means for refining clinical and laboratory diagnoses, with the aim of providing a basis for clinical assessments and animal management. The carcasses were gradually thawed, macroscopically evaluated for their appearance, measured, weighed, photographed, and necropsied. The characteristics of all the GIT organs (main and accessories) were evaluated, with measurement of the dimensions and description of the shape, consistency, and color of each one.

Results: The stomach of squirrel monkeys is simple and of non-compartmentalized type and the cecum does not have numerous folds, compared with other species. These characteristics are compatible with omnivorous simian species with no adaptive digestive specialization for the food fermentation process. Significant correlations were found between the weights of the carcass and GIT (p < .05); carcass and tongue (0.83; p < .01); and liver and right salivary gland (0.83; p < .01). It was also observed that the animals showed good body score conformation and GIT organs in good condition, which indicated that their nutritional management had been adequate. Regarding the correlations found among the organs: (i) squirrel monkeys with heavier carcasses had better-developed GIT with greater food storage capacity; (ii) the bigger the animal was, the greater its overall muscle development was, including that of the tongue, which would enable intensification of its feeding activity; and (iii) the measurements of the esophagus, small and large intestines, pancreas, and salivary glands were not sex-dependent in Saimiri sciureus.

Conclusions: Previously cryopreserved carcasses of squirrel monkeys can be used for gastrointestinal system studies, with the potential to make clinical, zootechnical, management, and scientific contributions.

Keywords: Saimiri sciureus; gastrointestinal system; morphometry.