Hypertrophy of mucosa and serosa in the obstructed intestine of rats

Abstract

After a surgically induced partial obstruction of the small intestine (ileum) in adult rats there is an accumulation of ingesta and a progressive enlargement of the lumen accompanied by wall thickening : over a period of 2-3 wk the circumference of the hypertrophic intestine increases by a factor of 2n7 and the thickness of the musculature increases more than threefold, while the length of the ileum (measured at the mesenteric attachment) remains unchanged. The villi become markedly larger and more elongated in the circumferential direction, and have a greater separation between one another. The number of villi per unit surface is markedly reduced but the number of villi per unit length of ileum, whilst appearing to show a small increase, was not significantly altered. The component epithelial cells (absorptive cells) appear unchanged in morphology and size (height). The microvilli of the epithelial cells have the same appearance, size (height) and packing density in the control and the hypertrophic ileum. Glands of Lieberku$ hn, Peyer's patches and single lymphatic follicles constituting the Peyer's patches are significantly increased in size in the hypertrophic intestine. The serosal surface of the hypertrophic ileum, in spite of the great expansion, remains regularly covered by mesothelial cells ; these are much larger than in the controls and have an altered distribution of their microvilli.Key words : Intestinal villi ; microvilli ; Peyer's patches ; mesothelium ; hypertrophy ; intestinal obstruction. When the flow of ingesta along the small intestine is impaired, as in the presence of a localised partial obstruction of the lumen, the intestine on the oral side of the obstruction becomes distended and hypertrophic. Enlargement of the lumen and distension of the wall are mechanical effects of the accumulation of ingesta. In contrast, hypertrophy is an active process of growth of the intestinal wall, mainly the musculature, the effect of which is that the wall, in spite of being very distended, is not thinner than in controls but conspicuously thicker. The occurrence of ileal hypertrophy, its relevance to medical conditions (such as obstructions due to pathologic growths or malformations), its scientific significance as a process of growth and adaptation of mature tissues, have been known for a long time. Herczel (1886) was probably the first to describe the structure of hypertrophic intestine, and the process has been analysed in Correspondence to Dr

Biomechanical Remodeling of the Chronically Obstructed Guinea Pig Small Intestine

“…The gastrointestinal partial obstruction model has been used in a number of experimental studies, primarily on changes in morphology and motility patterns [8,17,26]. It was demonstrated that pronounced morphologic and histologic changes were induced by the partial banding.…”

“…However, similar detailed data are not available for the partially obstructed intestine despite the initial work by Gabella [16], SchulzeDelrieu et al [17] and Storkholm et al [5,6,14]. Because of morphologic remodeling in the small intestine during obstruction [8,10], the biomechanical properties are also bound to change. Because biomechanics deals with the relation between stress (force per area) and strain (deformation), we consider the stress-strain relationship of the intestinal wall (stiffness) as the relevant quantitative remodeling parameters because they are measures of the nonuniformity of growth or resorption in different parts of the intestinal wall [13,18].…”

“…In chronic obstruction, the intestinal wall hypertrophies and luminal dilatation occurs proximal to the site of obstruction [8][9][10][11]. Altered biomechanical properties are believed to play a major role in the pathophysiologic process.…”

Serum Response Factor Is Essential for Prenatal Gastrointestinal Smooth Muscle Development and Maintenance of Differentiated Phenotype

“…The phenomena of SMC hypertrophy and hyperplasia, which occurs during partial bowel obstruction, has been previously well described. 13,22,23 Inflammation may also cause SMC hypertrophy within the GI tract. 24,25 However, the molecular mechanism remains less understood.…”

Intestinal Adenocarcinoma in a Herd of Farmed Sika Deer (Cervus nippon)

“…Muscle hypertrophy and hyperplasia of mural ganglia were observed in the deer proximal to the tumor mass, features thought to be induced by the increased workload required to overcome the obstruction. 4,5 Spontaneous intestinal neoplasia in animals is considered a rare event, 23 strongly suggesting that particular predisposing risk factors must be at play to account for such a high incidence of neoplasia in the study herd. This may reflect a genetic predisposition and/or environmental exposure to carcinogens.…”