Morphological characteristics of the rectum in chickens of different sexes

The morphology and blood supply of the rectum in chickens of different sexes were studied. Chickens of the Isa Brown cross were divided into two groups: females and males. In each group, macroscopic parameters of the intestine and the structure of the intestinal wall were characterized. The content of connective tissue fibers in the mucosal and muscular membranes was determined. Sex-related differences were weakly expressed in the external dimensions of the intestine and its blood supply. The significance of the sex factor increased in parameters characterizing the microscopic structure. Higher values of most studied parameters were observed in females. In terms of the number of goblet cells per villus, females exceeded males by 13.11 cells, or 14.52 % (P < 0.05), which resulted in a higher density of these cells within the villi. The thickness of the epithelium in females was greater by 5.16 μm, or 13.91 % (P < 0.05). The proportion of collagen and elastic fibers in the crypt region of the mucosa in females reached 9.49 ± 0.30 % and 3.07 ± 0.11 %, respectively. In the muscular membrane of females, these values were 14.86 ± 0.73 % and 9.49 ± 0.42 %, respectively. Males demonstrated a statistically significant predominance (by 3.54 μm, or 8.27 %, P < 0.05) in the total thickness of the muscularis mucosae together with the submucosa. In the intestinal wall of females, the proportions of the mucosal, muscular, and serous membranes were 48.29 %, 49.85 %, and 1.86 %, respectively. In males, these proportions were similar: 48.44 %, 49.70 %, and 1.86 %. Within the mucosa of females, its structural components (villi, crypts, and muscularis mucosae with submucosa) accounted for 35.06 %, 10.34 %, and 2.89 % of the intestinal wall thickness, respectively. In males, these values were 34.21 %, 11.01 %, and 3.22 %. In the structure of the myenteric plexus, females were characterized by a significantly higher number of nerve ganglia (78.24 ± 2.51 units) per 1 cm² of the intestinal wall. Males were inferior by 9.67 units, or 12.2 % (P < 0.05). Several instances of morphometric compensation between complementary parameters were observed, where higher values of one parameter corresponded to lower values of another. This indicates adaptive mechanisms of the intestinal wall that maintain structural balance.