FOWL SPERM IMMOBILIZATION BY A TEMPERATURE-MEDIA INTERACTION AND ITS BIOLOGICAL SIGNIFICANCE

¹ Institute of Animal Genetics, Edinburgh University, and Canadian Experimental Farm System, Ottawa

1. The motility of fowl sperm in vitro depends upon an interplay of temperature and medium of suspension. Most types of synthetic diluents support motility at room temperature but inhibit such at body temperature. The immobilization is not permanent and movement is again resumed when the temperature is lowered. Extremely low temperatures, i.e. just above freezing, also immobilize fowl sperm. Rat and guinea-pig sperm, on the other hand, are most active at body temperatures in the same synthetic diluents and are only immobilized by low temperatures, reactions which, according to the literature, appear to be generally characteristic of mammalian sperm.

2. Among natural fluids, sperm serum, blood serum, thin egg white and fluid from the shell gland support the motility of fowl sperm at all levels from 75° F. to 105° F. On the other hand, juice from the magnum or the infundibulum behave as synthetic diluents, immobilizing sperm at 105° F. but supporting motility at lower temperatures.

3. The facts summarized in (1) show that fowl sperm activity is under a delicate physiological control not operative in the rat or guineapig. This, together with the results summarized in (2), suggest that fowl sperm are motile in the shell gland of the female but are immobilized without injury to their functional abilities while in the magnum and infundibulum.

4. These suggestions are discussed in relation to the observations of other workers, and it is shown that not only are they tenable in the light of these reports but they actually support and logically integrate certain previously disconcerting findings.

5. The exact nature of the immobilizing mechanism is not clear, but it probably depends upon a complicated interaction between temperature, type, and pH level of the fluid environment.