The Fate of Spermatozoa in Female Dogfish (Scylliorhynus Canicula)

1. References are given to the literature concerning the fate, in various vertebrates, of spermatozoa in the female genital tract. 2. In the dogfish, penetration of the oviducal wall by spermatozoa does occur. It is confined to the ‘uterus’ and about five millimetres of the oviduct anterior to it. The latter suffers a denser invasion than the ‘uterus’. No spermatozoa invade the cloacal epithelium. 3. Epithelial vacuoles are found in the ‘uterus’, where they may or may not contain spermatozoa, and in the cloaca, where they do not. Any of the vacuoles may contain red and white blood corpuscles. 4. Vacuoles containing blood corpuscles account for a continuous ‘uterine’ bleeding on a small scale. 5. Desquamation of the ‘uterine’ epithelium is slow and continuous, that of the cloacal epithelium intermittent and heavy Desquamation is not related to the time of copulation. 6. Digestion of spermatozoa and blood corpuscles within the vacuoles may be very incomplete. 7. The spermatozoa which enter the columnar epithelium near the ‘uterus’, frequently pass right through and into the superficial connective tissue. No vacuoles are produced in the columnar epithelium. Presumably all such spermatozoa are phagocytosed. 8. No fusion occurs between the heads of the spermatozoa and the nuclei of any of the cells of the oviducal wall, as described by Kohlbrugge. 9. The proportion of spermatozoa destroyed in the lower oviduct is not sufficient to prevent them ascending the upper oviduct in large numbers. 10. A theory is advanced to account for the facts concerning the destruction of spermatozoa in the oviduct.