Basal epithelial surface

Basal epithelial surface In the airway, surface interfacing with basement... 

The histological types of lung cancer seen to excess in uranium miners reflect those in the population at large (Masse, 1984). These occur almost entirely in bronchial airways. Approximately 207 are adenocarcinomas which occur in peripheral bronchioles (Spencer, 1977) where there are no basal cells. Squamous cell cancers predominate in miners exposed early in life to relatively low concentrations of radon daughters (Saccomanno et aJL., 1982). These are considered likely to arise from the secretory small mucous granular cells which undergo cell division and extend to the epithelial surface (Masse, personal communication). Division of these cells is accelerated after irritation by toxicants such as cigarette smoke or infectious diseases (Trump et a L., 1978). 

While all the aforementioned cell types form the epithelial surface of the airways, basal cells reside deep in the tracheo-bronchial epithelium and are not directly in contact with the airway lumen. Basal cells are considered as the stem cell or progenitor cell of the bronchial epithelium and are pyramidal in shape with a low cytoplasmic/nuclear volume ratio [8, 15-17],... 

Wiche, G., Krepler, R., Ardieb, U., Pytela, R., and Aberer, W. (1984). Identification of plectin in different human cell types and immunolocalization at epithelial basal cell surface membranes. Exp. Cell Res. 155, 43-49. 

The apical membrane of a polarised cell is that part of the plasma membrane that forms its luminal surface, particularly so in the case of epithelial and endothehal cells. The basolateral membrane of a polarised cell refers to that part of the plasma membrane that forms its basal and lateral surfaces. Proteins are free to move from the basal to lateral surfaces, but not to the apical surface tight junctions, which join epithehal cells near their apical surfaces, prevent migration of proteins to the apical surface. The apical surface is therefore distinct from the basal/lateral surfaces. 

Re-epithelialization of comeal defects appears to depend in part upon the interaction of MMPs with matrix adhesion proteins on the exposed stromal surface to form the scaffolding for migrating basal epithelial cells (Fini et al 1996). Relative overexpression of MMPs may be a significant factor in refractory or indolent ulceration and in chronic superficial erosion in the horse. 

In addition to cholesterol present in the lumen, the intestinal epithelial cells are also exposed on their basal-lateral surfaces to cholesterol carried in circulating lipoproteins. It is of interest, therefore, to determine if variations in this source of... 

Fig. 249. Reoxygenation damage to the choroid plexus epithelium (block 641) from a 284 g male Wistar rat exposed to an atmosphere containing only 5 % oxygen for 30 min. Half an hour thereafter, under pentobarbital anaesthesia (30 mg/kg), the animal was perfused from the abdominal aorta with 2.5 % glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.4). Postfixation with 1 % osmium tetroxide in sodium cacodylate buffer (pH 7.4). Embedded in Epon 812 and sectioned at 50 nm. Lead citrate and uranyl acetate. Plate 3141. - The apical surface of the epithelium is composed of tightly packed, irregular microvilli. Basal epithelial infoldings...

Sugrue SR Hay ED (1981) Response of basal epithelial cell surface and Cytoskeleton to solubilized extracellular matrix molecules. J Cell Biol 91 45-54... 

Airway cross-sections have the nominal anatomy shown in Fig. 5.16. Airway surface liquid (AST), primarily composed of mucus gel and water, surrounds the airway lumen with a thickness thought to vary from 5 to 10 mm. AST lies on the apical surface of airway epithelial cells (mostly columnar ciliated epithelium). This layer of cells, roughly two to three cells thick in proximal airways and eventually thinning to a single cell thickness in distal airways, rests along a basement membrane on its basal surface. Connective tissue (collagen fibers, basement membranes, elastin, and water) lies between the basement membrane and airway smooth muscle. Edema occurs when the volume of water within the connective tissue increases considerably. Interspersed within the smooth muscle are respiratory supply vessels (capillaries, arteriovenous anastomoses), nerves, and lymphatic vessels. 

The cornea is the first structure of the eye to be in contact with incident light. It is composed of five distinct layers lying parallel to its surface the outer epithelium, which is continuous with the epithelial layers of the conjunctiva the epithelial basal lamina the keratocyte-containing stroma, which is a collagen structure arranged so that it is transparent Descemet s membrane and, finally, the endothelium adjacent to the aqueous humour. 

FIGURE 5-3 Immunocytochemical localization of the Na,K pump in choroid plexus. Choroid plexus contains epithelial cells with intensely stained microvillar and intermicrovillar plasma membranes. The basal and lateral plasma membrane surfaces are not stained. Bar = 2 im. (With permission from reference [81].)... 

The neural tube is a pseudostratified epithelium, with cells extending between the apical and basal surfaces of the epithelial wall. The neuroepithelium contains undifferentiated populations of stem cells and radial glia (see Ch. 29). With time, both of these cell types give rise to the three main lineages for neurons, astrocytes and oligodendrocytes. After the final mitotic division, neurons migrate away from the ventricular surface of the neural... 

The epidermis consists of several types of cells. The epidermal cell type apposed to the dermis is the stratum germinativum (basal cell layer), over which are the stramm spinosum, stratum granulosum, stratum ludicum, and the outermost layer or stratum corneum. The basal cell layer consists of one layer of columnar epithelial cells. On division, the basal cells are pushed up and become the stratum spinosum, which consists of several layers of cells. As these cells approach the surface of the skin they become larger and form the stratum granulosum. 

That is, the cotransporter can pump glucose inward until its concentration within the epithelial cell is about 9,000 times that in the intestine. As glucose is pumped from the intestine into the epithelial cell at the apical surface, it is simultaneously moved from the cell into the blood by passive transport through a glucose transporter (GLUT2) in the basal surface (Fig. 11-44). The crucial role of Na+ in symport and antiport systems such as these requires the continued outward pumping of Na+ to maintain the transmembrane Na+ gradient. 

Mammalian skin must be tough, water-resistant, self-renewing, and rapidly healing. The outer layers of cells or epidermis consist principally of keratinocytes, epithelial cells specialized for formation of keratin (Fig. 7-31). In the inner layer of the epidermis the basal stem cells divide, providing a constant outward flow of cells which become progressively flattened, dehydrated, and filled with keratin fibrils.3 The outer layers contain only dead cells which are finally sloughed or abraded from the surface. Human epidermis is completely renewed in about 28 days ... 

Figure 32-2 A pair of epithelial cells of Drosophila. The apical surface (top), e.g., of epithelial cells of the gut, faces the external surface, while the basolateral surface (bottom) binds to a basal membrane. Adheren junctions (AJ) and septate junctions (SJ) are shown between the cells. From Peifer and Tepass.84 Drawing by S. Whitfield.

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