sst2A-like immunoreactivity on formalin-fixed, paraffin-embedded testis sections. Tissue sections were incubated with R57 anti-sst2A antibody (1:500 dilution) alone (a) or in the presence of exogenously added antigenic peptide (b). Negative control consisted in staining procedure in which anti-sst2A antibody was omitted (c). Magnified frame from the middle of (a) is shown in (d) with arrow-heads pointing to immuno-negative spermatogonia. Magnified field from the bottom right in (d) is shown in (e) with simple arrows pointing to the immuno-labeled Leydig cells; dashed arrows point to immuno-negative Leydig cells. (f) another section plane with double arrows pointing to immuno-labeled spermatogonia in the interior of seminiferous tubule. Note the staining heterogeneity of both Leydig cells and spermatogonia (d-f). Scale bars: A-C = 100 μM; D = 50 μM; E-F = 25 μM.