| Abstract: | The results of experiments carried out at the Wisconsin Agricultural Experiment Station to test the possibility of controlling sex by artificial insemination with centrifuged spermatozoa in rabbits and swine are presented. Microscopic studies of spermatozoa showed dimorphism in the head lengths but separation by centrifuging was not complete. According to the chromosome theory, if the ovum is fertilized by an X-bearing spermatozoon, the resulting individual will contain 2 X chromosomes in its cells and will be female. If the ovumn is fertilized by a Y-bearing chromoxome spermatozoon, the resulting individual will contain and X and a Y chromosome in its cells and be a male. The Y-containing spermatozoa are thought to have smaller heads than the X-containing ones. Centrifugal separation of male- and female-producing spermatozoa was attempted with liquid recovered by means of a catheter from the vagina and uterus of rabbits. Other rabbits were then artificially inseminated with portions of this liquid and sex of young produced was recorded. Many young were produced from centrifuged spermatozoa and many from spermatozoa exposed to low temperatures for periods up to 24 hours. Modification of sex ratios was not significant. This investigation failed to show a practical method of controlling sex ratios among the offspring of higher animals. |
