Type IV Collagen a1 and a2 in Antral Follicles
Antibodies to the a1 and a2 chains of type IV collagen in antral follicles produced similar staining patterns (Fig. 2). In all of the follicles examined for a1(IV) staining and all except one of the antral follicles examined for a2(IV) staining, intense uneven staining was observed extracellularly throughout the theca interna (Fig. 2, a-c and e-g).
Its close proximity to the follicular basal lamina made staining of the follicular basal lamina difficult to interpret. Of the 22 follicles examined for a1(IV) staining, 17 were considered to have basal laminae that stained positively; of these, 14 stained with intensity equal to that for the thecal matrix, 2 stained more intensely, and 1 stained less intensely. In 5 of the 22 follicles examined for a1(IV), we were not confident in classifying the basal lamina as staining positively; if there was staining, it was at the same intensity as the thecal staining. Of the 21 follicles examined for a2(IV) staining, 20 were considered to have basal laminae that stained positively, and 1 did not stain for this chain. Of the basal laminae that did stain, 18 stained with intensity equal to that in the theca, although staining was often uneven in intensity along the basal lamina. The basal lamina of two follicles stained more intensely than the theca. proventil inhaler
Some of the extracellular staining observed in the theca interna was clearly associated with the endothelial basal laminae, but there were more areas staining positively for the a1 and a2 chains of collagen type IV than could be accounted for by the vasculature alone (compare Fig. 2, c with d and g with h).
FIG. 2. Immunofluorescent localization of type IV collagen a1 and a2 chains to antral follicles, and colocalization of factor VIII-related antigen. In each photograph, the location of the basal lamina is indicated by arrows, the membrana granulosa lies above the basal lamina and the theca below it, and the follicular antrum is uppermost. a-c) Positive staining for type IV collagen a1 in the follicular basal lamina as well as widespread staining in the theca are shown. Counterstaining of the section shown in c for factor VIII-related antigen, shown in d, demonstrated that the type IV collagen a1 staining is more widespread than the thecal vasculature. Similarly, staining for type IV collagen a2 (e-g) is present in the follicular basal lamina and widespread in the theca. Counterstaining of the section shown in g for factor VIII-related antigen, shown in h, demonstrated that the type IV collagen a2 staining is more widespread than the thecal vasculature. Follicle sizes: a, 3 mm; b, f (same follicle), 10 mm; c, d (same follicle), 5 mm; e, 9 mm; g, h (same follicle), 8 mm. Arrowheads indicate the vasculature. Bar = 50 ^m.