title: Mechanical components of rat intestinal villi as revealed by ultrastructural analysis with special reference to the axial smooth muscle cells in the villi.
abstract: The ultrastructure of the rat intestinal interstitium with regard to the mechanical components was analyzed from a functional viewpoint utilizing serial horizontal as well as longitudinal sections through the lamina propria mucosae, including both villi and crypts. The axial smooth muscle cells in the villi (villus-axial SMs) exhibited different configurations at various levels of the wall. They were separated from the voluminous fluid-filled spaces by sheet-like processes of fibroblasts in the upper part of the intravillous interstitium, formed a sheet around the central lymphatics, and were covered by the sheet-like processes of fibroblasts in the lower part of the intravillous interstitium. These villus-axial SMs were poorly developed and associated with the lymphatic walls in the upper part of the pericryptal interstitium; they were tapered and connected to microtendons composed of fascicles of longitudinal collagen fibrils in the lower part of pericryptal interstitium. At the apical termination, the villus-axial SMs were connected to myofibloblasts, which sent off many processes into the subepithelial meshwork layer of fine cell processes and extracellular matrices. The villus-axial SMs possibly develop longitudinal tension against the intravillous hydraulic pressure developing from the transepithelial absorption through the intestinal epithelium.
authors.affiliation: Department of Nutrition, Chiba College of Health Science, Japan.
authors.forename: Yasue
authors.initials: Y
authors.lastname: Hosoyamada
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Sakai
mesh_terms: D000818:Animals; D004386:Duodenum / Q000648:ultrastructure; D007413:Intestinal Mucosa / Q000648:ultrastructure*; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000648:ultrastructure*; D009210:Myofibrils / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar