Comprehensive characteristics of rectal morphology in chickens with different types of autonomous regulation

Abstract

The influence of typological features of autonomous regulation on the dimensions, structure, and blood supply of the rectum in chickens has been studied. The experimental group consisted of clinically healthy adult chickens of the Isa-Brown breed, divided into two groups using electrocardiography and variation pulsometry methods: chickens with sympathetic-tonic regulation and chickens with sympathetic-normotonic regulation. In each group, the length and diameter of the rectum, the branching of its arterial vessels, and the microscopic structure of the intestinal wall were examined. The corresponding artery provides the blood supply to the rectum, the branching of which showed no significant differences between the poultry groups. The peculiarities of autonomous regulation significantly influence the morphological structure of the intestinal wall’s mucous and muscular membranes. The serous membrane does not respond to these features. Chickens with sympathetic-tonic regulation (ST chickens) are characterized by a greater thickness of all indicated membranes and, consequently, the entire intestinal wall. Chickens with sympathetic-normotonic regulation (ST-NT chickens) have a greater thickness only in the muscular plate of the mucous membrane and its longitudinal layer. Regarding the quantity of collagen and elastic fibers, ST chickens dominate the mucous membrane’s crypt area, while ST-NT chickens dominate the muscular membrane. However, the density of connective tissue fibers in the mucous membrane is much lower than in the muscular one. The quantity and distribution of plasma cells have similar patterns in both groups. Specific morphometric compensation between two functionally related indicators is also an important aspect. In this case, larger values of one indicator are combined with smaller values of another. For example, a smaller diameter of the rectum in ST chickens is associated with its greater length; a smaller number of goblet cells on one villus corresponds to a larger area of their secretory section; a larger area of the nerve node of the intramuscular nerve plexus is combined with a smaller number of these nodes per 1 cm² of the intestinal wall. Thus, the structure of the rectum in chickens, adapting to the corresponding type of autonomous regulation, maintains the balance at the level of individual membranes and the entire intestinal wall.