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Fig. 2.
Colocalization of MMP-2 and SGP on the sperm surface. Sperm were treated with anti-MMP-2 HPX antibody and anti-SGP antibody followed by the secondary antibodies, showing the distribution of MMP-2 (green) in the head region including in acrosomal region (AC) and the middle and posterior portions of head (MH and PH). A small amount of MMP-2 was localized in the anterior portion of head (AH) and the tail region (T). SGP was distributed over the entire sperm surface (red). MMP-2 was colocalized with SGP on the sperm surface (merge with DIC image). Since the images (A–C) were taken from the same sperm with 1 µm-thick optical slices, only some areas of the sperm surface were shown in each image. The sperm were treated with Ca2+ ionophore A23187 (10 µM, 15 min) to induce acrosome reaction, and then treated with the antibodies, showing the localization of MMP-2 around the acrosomal region at the tip of the head (Fig. 2D). DIC, Differential interference contrast microscopy. Bars, 5 µm. |