Macro-anatomical, histological, and ultrastructural investigation of glandulae anales in Anatolian ground squirrels.

In this study, the anal glands of 10 adult Anatolian ground squirrels (Spermophilus xanthophrymnus) were examined through dissection, scanning electron microscopy (SEM), and light microscopy. The anal glands consist of three independent complexes positioned ventrolaterally to the anus. These glandular complexes were connected with the anal canal, the rectum, and with each other through muscular and connective tissue layers coursing in multiple directions. Each anal gland complex consisted of a glandular component and a sac-like structure. The sac structures of the anal gland complexes, which can evert, were visualized for the first time in this study using SEM. At the basal regions of the anal sacs, two distinct types of glandular clusters were identified. Type I apocrine glands, characterized by short excretory ducts, were located adjacent to the sac base, whereas Type II holocrine glands, with longer tubular ducts, were situated more distally. The study identified the presence of numerous interconnected sinusoidal vascular structures in both the glandular region of the anal complex and in the inner portions of the muscle bundles surrounding the anal complexes. These sinusoidal capillaries, previously unreported in the anal glands, likely represent erectile structures that engorge with blood and generate pressure to facilitate anal complex function.