Fig. 3. BC1 expression in developing seminiferous tubules. (A,B) At postnatal day 7 (p7), BC1 labeling in developing tubules is robust but heterogeneous. Arrows indicate hotspots of BC1 expression in several tubules. Note that more heavily counterstained cells typically exhibit little or no specific BC1 labeling. (C) At p17, only cells in peripheral-most layers show strong labeling; asterisk indicates the position of cells in adluminal layers (presumably spermatocytes) that exhibit little specific labeling. (D) The adult expression pattern is shown for comparison. Exposure time for D was three times longer than for A-C. (A,C,D) Dark field photomicrographs; (B) bright field photomicrograph. Bar: 40 µm (A,B); 50 µm (C,D).