This is the first study to localize any of the six a chains of type IV collagen within the follicular basal lamina of any species. The follicular basal lamina of primordial and small preantral follicles contained all of the a chains of type IV collagen. In antral follicles, there was widespread extracellular staining throughout the theca interna for the ai and a2 chains, often making it impossible to determine whether the follicular basal lamina itself contained these chains. The a3, a4, and a5 chains were not detected in some antral follicles. When it was present, the level of staining was less intense than at earlier stages of follicular development. The a6 chain was not detected in the follicular basal lamina of any antral follicles. In the light of the current study and a previous study of individual laminin chains in the ovarian follicle, it is clear that important changes take place during follicular development, both in the composition of the follicular basal lamina and in the development of a thecal matrix in the mesenchyme, adjacent to the follicular basal lamina. buy cipro
There are currently 15 different classes of collagen; however, only type IV collagen is found predominantly in basal laminae. Each type IV collagen molecule contains three a chains wound into a triple helix. In all, six different a chains have been discovered, and a type IV collagen molecule may contain any combination of these chains although some combinations, such as a1(IV)2 a2(IV), are more common than others.