Особливості будови стравоходу та його лімфоїдної тканини горобця домового (Passer domesticus)

Abstract

The features of the structure of the esophagus and its lymphoid tissue of the house sparrow (Passer domesticus) have been studied. It is shown that its wall is formed by well expressed mucous, muscular and least developed adventitial (serous in the caudal part) shells. The mucosa forms 7–9 longitudinal folds of leaf-shaped and finger-shaped forms directed into the lumen of the esophagus. It consists of epithelium, lamina propria, lamina muscularis and submucosa. The epithelial layer is represented by a multi-layered flat, weakly keratinizing epithelium and is better developed in the cranial part of this organ. Near the proventriculus, it passes into a single-layered cylindrical. In its lamina propria of the mucosa there are bags of numerous large esophageal glands in which mucus is recorded. Their excretory ducts open onto the surface of the mucosal epithelium. The lamina muscularis is intermittent in places, formed by a smooth muscle tissue. The submucosa is weakly expressed and its own plate is formed by a loose fibrous connective tissue with blood vessels. Between the esophagus glands, their excretory ducts and in the submucosa of the tunica mucosa on the border with the tunica muscular are separate clusters of diffuse lymphoid tissue, which are represented by cells of the lymphoid series without noticeable rarefaction and densities. The basis of the diffuse lymphoid tissue is the reticular tissue, the fibers of which, are densely disposed and do not have a definite orientation and form a small grid. In the area of transition of the esophagus to the proventriculus, the esophageal tonsil, which is inherent in many species of birds, is not expressed. In this area in the mucous membrane, only local accumulations of diffuse lymphoid tissue are recorded. There are no prenodules and lymphoid nodules. The tunica muscular of the esophagus is formed by a smooth muscle tissue, which forms the inner–circular and outer – longitudinal layers. Between them, layers of loose fibrous connective tissue and blood vessels are identified. Tunica adventitia (serosa) are formed by a loose fibrous connective tissue, and serosa is also covered by mesothelium.