ULTRASTRUCTURAL, HISTOCHEMICAL, IMMUNOCYTOCHEMICAL, AND LIGHT MICROSCOPIC OBSERVATIONS OF THE TERMINAL PORTION OF THE OBSTRUCTED AND NORMAL EQUINE SMALL INTESTINE (SUBSTANCE, CHOLINESTERASE, GASTROENTEROLOGY)

JEROME MASTY, Purdue University

Abstract

This project was designed to investigate the degree of morphologic change in the mucosal epithelium and in the muscle fibers of the muscularis externa of the intestinal wall as a function of increasing distance from the site of a simple obstruction in the terminal portion of the equine small intestine. A secondary goal was to demonstrate the presence of Substance P, a gastrointestinal hormone, and the sites of cholinesterase activity within the layers of the intestinal wall in the normal and obstructed tract of the equine species. An obstructor band was surgically implanted around a segment of the terminal small intestine in seven mature ponies. The ends of the obstructor were tunnelled retroperitoneally and exteriorized through a stab incision in the left flank. After a postoperative recovery period of at least four days, the band was tightened to produce a simple obstruction of the intestine. After twelve hours, the ponies were euthanized and tissue samples collected for analysis. Tissue collected from seven ponies that were not experimentally obstructed served as normal samples for comparative purposes. The villous lining of the mucosa showed no signs of degeneration after the twelve hour period, while the morphology of the glandular epithelium indicated an increased stimulus for secretion. The smooth muscle fibers showed beginning signs of vesicular formation within the cells. Distance from the site of obstruction did not appear to influence the changes seen in the epithelium or the muscle tissue. Substance P was localized primarily within neurons of the submucosal ganglia and in nerve fibers of the myenteric plexus. Focal sites of reaction were seen within the circular layer of smooth muscle. Acetylcholinesterase was demonstrated in the ganglia and nerve bundles of the myenteric and submucosal ganglia, small nerve fibers in the submucosa and lamina propria, and was seen diffusely only in the circular layer of the muscularis externa. Nonspecific cholinesterase was present in these areas and especially in the longitudinal layer of the muscularis externa and in the muscularis mucosae.

Degree

Ph.D.

Subject Area

Veterinary services

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