Macroscopic and Microscopic Organization of the Intestine in the Arabian Jerboa (Jaculus loftusi): Adaptive Significance for Desert Survival.

The Arabian jerboa (Jaculus loftusi) able to thrive in one of the harshest conditions on the earth, where water is scarce and food is often dry and fibrous. To understand how this small desert rodent manages such challenges, we examined the structural and functional modifications of the hindgut in eight adult male individuals collected from Aljouf desert in northern Saudi Arabia. The digestive tract was about 62.7 cm long, nearly five times the jerboa's body length with the small intestine making up the greatest share (55.9%). The large intestine was characterized by a sacculated cecum serving as a fermentation chamber. Histologically, the small intestine exhibited finger-like villi with varying heights depending on the region, lined by simple columnar ciliated epithelium, interspersed with numerous goblet cells. Interestingly, the duodenum lacked Brunner's glands, which typically exist in many other mammals. The cecum had short mucosal folds, while the colon rectum displayed prominent folds with deep crypts of Lieberkühn, features well suited for breaking down cellulose and supporting microbial fermentation. Histochemical examination revealed the predominance of acidic mucopolysaccharides, likely helping to retain water, lubricate the gut lining, and support a healthy microbial environment. Together these structural and histochemical traits highlight how the jerboa's hindgut is finely tuned to extract maximum nutrients and conserve water, key adaptations that allow this amazing animal to survive and flourish in the extreme conditions of the desert habitat.