Figure 10. Localization of MUPP1 in fixed human sperm. Subcellular localization of MUPP1 in human sperm is showing by indirect immunofluorescence using a rabbit polyclonal anti-MUPP1 antibody and a FITC-conjugated second antibody. Binding of FITC-PNA displays fluorescence over the acrosomal region of the head (B). Note that MUPP1 is localized to the acrosomal cap (C, D); a few sperm which undergo spontaneous acrosome reactions only show strong MUPP1 labeling of the equatorial segment (E). (A) Secondary antibody alone. (B–D) Overlay of corresponding fluorescence images.