Consistent with this, the presence of individual chains of laminin was shown to alter with follicular development and atresia. Im-munolocalization studies of the follicular basal lamina have demonstrated the presence of type IV collagen but have not identified which isoforms are present. In another study utilizing Northern blotting, the expression of the a2 chain was detected in granulosa cells, and the expression of the a3 chain was detected in both the theca and granulosa cells. The chains were not specifically localized to the follicular basal lamina; this is important, as there are other basal laminae in follicles, such as those of the thecal vasculature, and our studies have identified an extracellular ‘‘thecal matrix’’. Furthermore, none of these studies have considered changes in the collagen component of the follicular basal lamina with follicular development and atresia. buy ventolin inhalers
As type IV collagen is one of the most important structural components of basal laminae, in the current work we investigated the specific type IV collagen composition of the follicular basal lamina and the ways in which it changes with follicular development. Type IV collagen was immu-nolocalized in bovine follicles, and Western blot analyses were conducted on isolated follicles using antibodies specific to the a1, a2, a3, a4, a5, and a6 chains of type IV collagen.