Lamina cells smooth

The normal arterial wall consists of the intima, media, and adventitia, as illustrated in Fig. 4—3A. The endothelium is located in the intima and consists of a layer of endothelial cells that line the lumen of the artery and form a selective barrier between the vessel wall and blood contents. The internal elastic lamina separates the intima and media, where vascular smooth muscle cells are found. The vascular adventitia comprises the artery s outer layer. Atherosclerotic lesions form in the subendothelial space between the endothelial cells and internal elastic lamina. 

Mucosa. The innermost layer of the wall is the mucosa, which consists of a mucous membrane, the lamina propria, and the muscularis mucosa. The mucous membrane provides important protective and absorptive functions for the digestive tract. The nature of the epithelial cells lining the tract varies from one region to the next. Rapidly dividing stem cells continually produce new cells to replace worn out epithelial cells. The average life span of these epithelial cells is only a few days. The lamina propria is a thin middle layer of connective tissue. This region contains the capillaries and small lymphatic vessels that take up the digested nutrient molecules. The muscularis mucosa is a thin layer of smooth muscle. Contraction of this muscle may alter the effective surface area for absorption in the lumen. 

Pulmonary arterial effects. Cigarette smoke, administered to 2- and 3-month-old rats at a dose of one cigarette 10 times a day, increased significantly the volume fractions of the fibroblasts, the collagenous bundles, and the elastic laminae of the pulmonary arteries. The volume fractions of smooth muscle cells and the remainder were decreased significantly in both groups compared to controls. An increase in the stiffness of the pulmonary arteries was found in both the 2- and 3-month smoke-exposed rats . ... 

The mouth and esophagus are composed of two layers, the mucosa and submucosa (Figure 3.5). The mucosa is lined on its outer surface by a stratified squamous epithelium with layers of polyhedral cells of the intermediate layers and low columnar cells of the basal layer. Below the cellular layer is the lamina propria containing loose connective tissue with blood vessels and small aggregates of lymphocytes. Smooth muscle within the mucosa (muscularis mucosal layer) is seen as small bundles. The submucosa... 

The epithelium is supported underneath by lamina propria and a layer of smooth muscle called muscularis mucosa (3-10 cells thick). These three layers, i.e., the epithelium, lamina propria, and muscularis mucosa, together constitute the intestinal mucosa.On the apical surface, the epithelium along with lamina propria projects to form villi. The cell membranes of epithelial cells that comprise the villi contain uniform microvilli, which give the cells a fuzzy border, collectively called a brush border. These structures, although greatly increase the absorptive surface area of the small intestine, provide an additional enzymatic barrier since the intestinal digestive enzymes are contained in the brush border. In addition, on the top of the epithelial layer lies another layer, the UWL, as previously described. The metabolic and biochemical components of the epithelial barrier will be discussed. 

FIGURE 2.2 A transmission electron micrograph of the luminal aspect of the wall of a large cortical arterial branch of the middle cerebral artery of the rat after application of endothelin-1 to the latter. Endothelial cells are lucent with a vacuolated cytoplasm (top), there is denudation of the basal lamina (arrowhead), and there is structural damage to smooth muscle cells in the tunica media (lower half of figure). (Original magnification x 3,600.)... 

The epithelial layer is in immediate contact with the lumen of the gastrointestinal tract. The lamina propria, which functions as a structural support for the epithelial layer, is situated on the basolateral side of the epithelial layer. The lamina propria contains lymph vessels, smooth muscle cells, nerves, and blood vessels, which nourish the epithelium. The muscularis mucosa makes up the deepest layer, which is thought to be involved in contractility.8 A more detailed description of the forces that hold together the epithelial layer is provided below. 

The normal artery wall is composed of three layers intima, media, and adventita (Figure 20-10). On the luminal side, the intima contains a single layer of endothelial cells. These cells permit passage of water and other substances from blood into tissue cells. On the peripheral side, the intimal layer is surrounded by a fenestrated sheet of elastic fibers (the internal elastic lamina). The middle portion of the intimal layer contains various extracellular components of connective tissue matrix and fibers and occasional smooth cells, depending on the type of artery, and the age and sex of the subject. 

The adventitia is separated from the media by a discontinuous sheet of elastic tissue (the external elastic lamina) and consists of smooth muscle cells, fibroblasts, collagen fibers, and glycosaminoglycans. This layer is supplied with blood vessels to provide nutrients. 

The normal artery is composed of three distinct layers (Fig. 34.21). That which is closest to the lumen of the vessel, the intima, is lined by a monolayer of endothelial cells that are bathed by the circulating blood. Just beneath these specialized cells lies the subintimal extracellular matrix, in which some vascular smooth muscle cells are embedded (the subintimal space). The middle layer, known as the tunica media, is separated from the intima by the internal elastic lamina. The tunica media contains lamellae of smooth muscle cells surrounded by an elastin- and collagen-rich matrix. The external elastic lamina forms the border between the tunica media and the outermost layer, the adventitia. This layer contains nerve fibers and mast cells. It is the origin of the vasa vasorum, which supply blood to the outer two thirds of the tunica media. 

Davis EC (1993) Smooth muscle cell to elastic lamina connections in developing mouse aorta. Role in aortic medial organization. Lab Invest 68 89-99... 

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