Figure 5. Distribution of caveolin and flotillin in paraffin-embedded sections of rat testis. After antigen retrieval, caveolin and flotillin were visualized using anticaveolin and antiflotillin-1 antibodies (Transduction), biotinylated secondary antibodies (Chemicon), streptavidin horseradish peroxidase (HRP) conjugate, and aminoethyl carbazole (AEC) (red) substrate (Zymed). Caveolin localization was specific to the peritubular myoid cells (PMCs) of the seminiferous tubules. Within the interstitium, the walls of the blood vessels also showed intense reaction product (Panels A, B). Flotillin-1 distribution was stage-specific, with intense labeling observed around the spermatid heads prior to spermiation (Panel C). Reaction product was also observed in the basal compartment of the seminiferous tubules with significant quantities of label present in late spermatogonia and early spermatocytes (Panel D). Without the antigen retrieval process, no flotillin-1 reaction product was visible (Panel E).