Figure 5. Caudal mouse spermatozoa that were incubated in the capacitation medium for 1 hour were further incubated for 30 minutes in the absence (A) or presence (B) of 1 mM Ca²⁺ ionophore. They were then processed for immunostaining with the anti–bactericidal/permeability-increasing protein (BPI) antibody followed by DNA staining. Note that BPI disappeared in Ca²⁺ ionophore-treated spermatozoa (B).

Figure 6. (A, B) Confocal laser scanning microscopy of bactericidal/permeability-increasing protein (BPI) in epididymis of castrated rats. Frozen sections of caput (A) and cauda (B) epididymides are stained with the anti-BPI antibody followed by incubation with the anti-rabbit immunoglobulin G (IgG) conjugated with Cy-3 (left panels). Nuclear DNA was stained by SYTOX-Green. Confocal images produced by superposition of BPI (left) and nuclear DNA are shown in the right panels. Note that the BPI immunosignal is not detectable in both caput and cauda. (C) Immunoblot analysis of BPI expression in epididymides of control and castrated rats. Proteins extracted from caput and cauda epididymides are separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and either stained with Coomassie brilliant blue (left panel) or subjected to immunoblot analysis using the anti-BPI antibody (right panel). Expression levels of BPI in both caput and cauda epididymides are down-regulated by castration. Molecular masses of the standard proteins are shown on the left (M_r x 10^–3). Color figure available online at www.andrologyjournal.org.