Ansa Spiralis Variation in the Ascending Colon of Sheep

Abstract

Sheep (Ovis aries) are ruminant animals, and a key feature they share with other species in this classification is the structure of the ascending colon, specifically the ansa spiralis (also commonly called the spiral ansa, spiral colon or ansa spiralis coli). In sheep, this structure generally forms a discoid spiral, consisting of two to four centripetal gyri, which transition at the central flexure into two to four centrifugal gyri, but some sheep exhibit deviations from this classic form. Current anatomical textbooks and scientific articles lack detailed descriptions relating to all of these possible variations of ansa spiralis in this species. This study identified and documented all of the deviations and their frequencies. The study was conducted from carcasses collected at a slaughterhouse in Tirana, Albania. In total, 555 large intestines from randomly selected sheep over the age of 6 months were evaluated. No records were kept regarding specific age, sex, breed, or region of origin. Among the 555 large intestines, 52 (9.37%) exhibited different ansa spiralis shapes compared to the classical form. Among these irregularly shaped samples, 12 distinct variations were discovered. This study offers valuable insights into the sheep large intestine morphology and lays the groundwork for further research. Future studies could focus on detailing ansa spiralis vascularization or investigating the relationships between ansa spiralis shape deviations, frequencies and factors such as sex, breed, age, diet and region.