The cover image shows Immunofluorescent/differential interference contrast (DIC) micrographs (A–H) and diagrammatic representations (a–h; modified from Holstein and Roosen-Runge, 1981) of enzyme-dissociated human testicular cells stained with 4(6-diamidino-2-phenylindole) (DAPl) II for DNA (blue), fluorescein isothiocyanate (FITC) for the acrosomal protein SP-10 (green) and tetramethylrhodamine B isothiocyanate (TRITC) for the SPANXa/d protein (red). (A) This early round spermatid demonstrates a small acrosomal vesicle (overlying the nucleus) stained with the acrosomal marker SP-10 (green). SPANXa/d staining is associated with the nuclear periphery. (B) Early capphase spermatid showing SPANXa/d staining of the nuclear periphery posterior to the early acrosomal cap. As the acrosomal cap migrates posteriorly and the spermatid begins to elongate (C–F), SPANXa/d staining is associated with the nuclear envelope posterior to the acrosomal cap. In D and E, it is evident that a SPANXa/d-negative region intervenes between the equatorial bulbs on either side of the acrosome and the SPANXa/d-positive nuclear envelope. In elongated spermatids (G) and testicular spermatozoa (H), SPANXa/d staining is seen in the posterior head and cytoplasmic droplet. Occasional nuclear vacuoles demonstrating SPANXa/d staining are observed (B and C, arrows). Blue, DNA; red, acrosomal protein SP-10; green, SPANXa/d. A, acrosome; An, annulus; C, centriole; Fs, flagellum; M, mitochondria; Mt, manchette; N, nucleus; Sb, spindle-shaped body. (See V.A.Westbrook et al., pp. 703–716).
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