Basal laminas structure

Perlecan 600,000 Heparan sulfate 2-15 Basal laminae Structural and filtering function in basal lamina... 

An electron-microscopic study showed that growth cones and filopodia of the Til neurons in the embryonic grasshopper limb bud contact the basal lamina, rather than the ectoderm of the limb bud (Anderson and Tucker, 1988). These authors concluded that guidance cues for these axons reside in the basal lamina, rather than the ectoderm. They also found that there is a proximal-distal gradient in basal lamina structure, with thinner basal lamina at the tip and thicker at the base (Anderson and Tucker, 1989). This correlates with the proximal-distal orientation of the pioneering Trl axons and it was suggested that this correlation may be a causative one for guidance of the Trl axons. 

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. 

The second class of AChEs exists as heteromeric assemblies of catalytic and structural subunits. One form consists of up to 12 catalytic subunits linked by disulfide bonds to filamentous, collagen-containing structural subunits. These forms are often termed asymmetric, since the tail unit imparts substantial dimensional asymmetry to the molecule. The collagenous tail unit links by disulfide bonding at its proline rich N-terminus through a coiled coil arrangement to the C-terminus of two of the catalytic subunits [30]. The tail unit associates with the basal lamina of the synapse rather than the plasma membrane. 

Figure 1.10 Columnar and stratified epithelia. Epithelial b ssues are underlain by a basement membrane which is a composite structure composed of an amorphous basal lamina, secreted by the epithelial cells, and a more fibrous reticular lamina derived from connective tissue.

Electron micrographs of these glands show structures which would be in keeping with this interpretation614. Arising from the basal lamina are numerous membranous infoldings. The lateral membranes are closed by tight junctions at the lumenal surface but freely open into to blood sinuses on the serosal surface. The lumenal surface contains many microvilli (Fig. 6). 

The ECM that surrounds cells also contains variable levels of HA. It is composed predominantly of structural proteins such as collagen and elastin, as well as proteoglycans, and a number of glycoproteins. The HA content is greatest in embryonic ECM, and in tissues undergoing rapid turnover and repair. The basal lamina or basement membrane that separates dermis and epidermis is also considered an ECM structure. The basal lamina contains HA, though the precise structural position is not known. Loss of basement membrane HA in the skin of diabetic patients correlates with skin stiffness.50... 

Fig. 7.11. Comparison of the fine structure of the membranes of the eggs of Hymenolepis diminuta and H. nana. Note in H. nana (in contrast to H. diminuta) (a) the embryophore is thin and incomplete - a feature which may facilitate hatching in the gut of the definitive host (b) there is an additional polar filament layer between the oncospheral membrane and the basal lamina. Gc, Golgi complex ger, granular endoplasmic reticulum /, lipid bodies m, mitochondria n, nucleus v, vacuoles. (After Fairweather Threadgold, 1981a Holmes Fairweather, 1982.)...

Biodistribution of plasmid to either extracellular or intracellular targets is dependent on the structure of capillary walls, (patho)physiological conditions, the rate of blood and lymph supply, the physicochemical properties of plasmid and its carrier molecules. The fate of plasmid after in vivo administration is illustrated in Figure 14.4. The blood capillary walls are comprised of four layers, namely plasma-endothelial interface, endothelium, basal lamina, and adventia. Macromolecules can cross the endothelial barrier ... 

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.)... 

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