Figure 5.

Localization of immunoreactive PTGS2 and 5 forms of PLA₂ in rat preovulatory follicles. Normal rat ovaries at hCG8h were immunostained for PTGS2 and 5 PLA₂s. A) Negative control (nonimmune serum). B, C) PTGS2 signals localization to most, but not all, mature follicles (B) and mainly to cumulus oophrus (CO) and throughout granulosa layers (GL) but not to oocyte, thecal layers (TL), and the stroma (St) (C). D) Abundant PTGS2 localization on nuclear membranes (black arrowheads). E, F) PLA₂G1B (E) and PLA₂G2A (F) localization to cumulus oophorus and granulosa cells lining the antral surface (arrowheads). G) PLA₂G5 localization only to thecal layers of mature follicles. H, I) PLA₂G4A signals in cumulus oophrus, granulosa layer, and oocytes and frequently on the hematoxylin-stained nucleus structures (I, black arrowheads). The mirror-image technique on the pair of adjacent sections (C and H, D and I) showed frequent colocalization of PTGS2 and PLA₂G4A signals at the cellular level (blue and green arrowheads in each panel). J) PLA₂G6A localization to thecal layers and oocytes of mature follicles. To investigate the association of PTGS2 and PLA₂s in the identical follicles, serial sections were stained for PTGS2 and PLA₂s. Immunoreactivities in a total of 47 follicles from 3 ovaries (see example in panel B) were semiquantitatively evaluated and summarized in Fig. 6. Scale bars = 400 μm (B); 200 μm (A, C, E, H); 100 μm (F, G, J); 20 μm (D, I).