Fig. 2. Histone H3 lysine 4 methylation in male germ cells. Gonads from transgenic PD7271 males were fixed in paraformaldehyde and stained with the 
-H3 dimethyl K4 antibody (green) and counterstained with DAPI (red). A1-A3 illustrate each signal separately and after merging; (B-F) the merged signals only. Arrows in all panels point to the X chromosome in each nucleus. (A) Pachytene stage; (B-D) progressive stages of primary spermatocytes; (E) condensing secondary spermatocytes; (F) spermatids. Arrowheads in B,C indicate transgenes. Transgenes were identified in all experiments by z-axis optical scanning through nuclei to rule out confusion with chromosome ends. Scale bars: 5 µm.
