Fig. 3. Differential expression of p90Rsk2 and p90Rsk3 in mouse spermatocytes and spermatids. Histological sections obtained from adult testis were stained with antibodies directed against the three p90Rsk isoforms. Immunostaining was carried out using the anti-p90Rsk1, anti-p90Rsk2 or anti-p90Rsk3 antibody and a rhodamine-conjugated secondary antibody as described in the Materials and Methods. Sections were also stained with Hoechst 3332 to detect chromatin (right panels). In all panels, L stands for lumen of the tubule and B for basal lamina. In the anti-p90Rsk2 panels, the arrowheads indicate a representative spermatocyte, whereas in the anti-p90Rsk3 panels, the arrowheads point to a representative elongated spermatid (central tubule) and a representative round spermatid (lower tubule). The layer of spermatogonia just above the basal lamina is stained by both the anti-p90Rsk2 and the anti-p90Rsk3 antibody.