Summary
The fine structure of epididymal spermatozoa of boars was studied, with special regard to the head cytoplasm, the neck, and the axial filament. Epon embedding and “staining” with heavy metals was used.
The acrosome consists of a moderately opaque, homogeneous substance bounded by a single membrane. Within the distinct equatorial segment, the acrosome is very thin and separated from the nuclear membrane by a narrow rim of moderately dense material, which may be related to the perforatorium of rat spermatozoa.
The postnuclear cap consists of a dense, homogenous substance inside the cell membrane and is stainable with phosphotungstic acid.
The fibre structures of the neck are surrounded by folded extensions of the nuclear membrane. Two short, dark rods appear in the centre of the neck. The “light segments” of the coarse, peripheral fibres are merely deep notches in the fibre substance. The coarse peripheral fibres reach their maximal thickness at the anterior end of the middle piece. They taper rapidly anteriorly from this point and more gradually posteriorly. Irregular bridges connect them with each other in the anterior middle piece.
The central 9+2 fibrils of the axial filament have distinct “arms” and “spokes” in the middle piece and main piece. The subfibrils connected with the arms and spokes appear to be solid, except in the neck and end pieces. The two central fibrils run through the neck to the wall of the proximal centriole.
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Acknowledgements. We wish to express our sincere gratitude to Dr. B. Afzelius, the Wenner-Gren Institute, Stockholm, for helpful discussions regarding tail fine structure, and to Dr. J. Luft, Department of Anatomy, University of Washington, Seattle, Wash., U.S.A., for the generous supply of ingredients for the Epon embedding procedure.
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Nicander, L., Bane, A. Fine structure of boar spermatozoa. Zeitschrift für Zellforschung 57, 390–405 (1962). https://doi.org/10.1007/BF00343326
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DOI: https://doi.org/10.1007/BF00343326