Fibronectin, heparan sulfate proteoglycans, and other molecules are associated with the type IV collagen-laminm backbone. Importantly, basal laminae in different regions of the body differ in the ratio of all these components. Furthermore, each “component” is a class of several isoforms. The type IV collagen molecule is composed of three separate a chains; but six different isoforms, encoded by separate genes, have been discovered to date. Potentially, any combination of the chains might be present, although some combinations such as ([a1]2, a2), (a3, a4, a5), and (a5 with a6) are more common than others. It is considered that the unique composition of each basal lamina, determined by the ratios of the different components to each other and of the specific isoforms of each component present, contributes to its specific functional properties. For example, changes in the composition of a basal lamina can affect its ability to selectively filter materials, as occurs in the renal glomerulus. buy cipro
During follicular development, there is a 317 400-fold increase in the area covered by the basal lamina from the primordial follicle to the 18-mm follicle. This implies that the follicular basal lamina is continually remodeled during follicle growth. We have previously hypothesized that the composition of the follicular basal lamina changes during follicular development and atresia.