GALVANIC SEPARATION OF X- AND Y-CHROMOSOME-BEARING SPERM1

Abstract

Researchers generally agree that nonmotile or immobilized sperm all possess negative charges on their outer surfaces and migrate toward the anode in neutral buffers. When motile sperm are electrophoresed exceptions occur. The 2-way migration of motile sperm was not strictly electrophoresis but might better be described as galvanic separation. Inseminations with such sperm have been reported to produce significant deviations from expected sex ratios of progeny. This research with rabbit and bull sperm was designed to study such phenomena. Details of methods used are given. When data were analyzed the tendency of cathode-migrating sperm to result in male offspring seemed limited to samples with motility greater than 5% but this deviation was not significant. Accumulated sex ratio data from insemination with rabbit and bull sperm after electrophoresis in 3 different cells and observations during electrophoresis in another cell included a total of 1291 young. These data yielded ambiguous results. Motile sperm became oriented as head-anode or tail-anode within about 5 seconds. As electrophoresis progressed motile sperm became sluggish and finally mobiligy ceased. All nonmotile sperm migrated toward the anode. A total of 366 rabbits from experiments with a newly devised 3-chambered cell yielded a clear majority of females from anode sperm with .10 M phosphate and 5% egg yolk buffer while with .14 M phosphate it did not. Another experiment indicated that separation of X- and Y-chromosome-bearing sperm was more effective at 30 degrees C than at 10 degrees C. Neither repetitive ejaculations nor washing sperm before electrophoresis altered sex ratios from either anode or cathode sperm. Fertility of electrophoresed sperm following freezing was poor. Among 60 calves born there was little evidence of a separation of X- and Y-chr omosome-bearing sperm. Discussion and questions by others follow.