Changes in the morphology and behaviour of spermatozoa between copulation and fertilization in the Japanese long-fingered bat, Miniopterus schreibersii fuliginosus

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Abstract
Live spermatozoa were first stored in the colliculus tubaricus of the uterotubal junction (UTJ) on both sides. Spermatozoa then ascended to the caudal isthmus just before ovulation. Spermatozoa with intact acrosomes in the caudal isthmus, which had their heads orientated towards the cephalic isthmus, were seen amongst groups of epithelial cilia in parallel to the epithelium; on the other hand, acrosome-less spermatozoa that were not attached to the epithelium were orientated irregularly in the lumen. A few acrosome-intact spermatozoa were found in the left ampulla at the time of ovulation of the single egg on the left side. Most of the spermatozoa failed to reach or survive in the ampulla of the right oviduct and leukocytic phagocytosis was restricted to this side.