Seasonal changes in gut morphology of the striped field mouse (Apodemus agrarius)

I studied seasonal changes in length and wet mass of the digestive tract and area of the mucosal surface of the small intestine in wild adult striped field mice (Apodemus agrarius). The length and mass of the gut varied with season in males but not females. The mucosal surface area of the small intestine was highly correlated with seasonal variations in the size of the alimentary tract. Changes in the surface area of the mucosa depended on changes in both villus size and the number of villi per unit area. The area of the intestinal mucosa varied during the year in both females and males, but unexpectedly, the mucosal surface area in females was significantly larger than in males only in autumn. Because gut size decreased toward late autumn, I suggest that late autumn was not a stressful period (i.e., because of low temperature or poor-quality food) for wild field mice. The decrease in gut parameters may have been an effect of declining metabolic requirements and completion of reproduction in late autumn.