Effect of the T locus on sperm distribution in the house mouse

Spermatozoan distribution in the female genital tract following matings with sterile tw18/tw32 male mice was studied both by examining the fiushings and by examining histological sections of the genital tracts. Spermatozoan counts were made on fiushings from various parts of the genital tract after matings from 9 hr before ovulation to 10 hr after ovulation. Usually, the lower tracts (uterus and upper half of vagina) of females mated with sterile males contained normal numbers of spermatozoa, as did the lower tracts of females mated to fertile littermates or to other fertile males having only one of these two t-alleles. However, matings with sterile males resulted in few or no spermatozoa reaching the site of fertilization in the oviducts, whereas matings with control males resulted in numerous spermatozoa at the fertilization site. The complex T locus in the ninth linkage group of the house mouse has a number of interesting properties. One is that male mice carrying certain combinations of t-alleles are sterile, though they produce spermatozoa and mate normally. Females of the same geno-types are fertile. Braden and Gluecksohn-Waelsch (1958) observed very few or no spermatozoa in the oviducts of normal female mice mated to male mice of genotypes t#{176}/t3, t#{176}/t4, t1/t4, t1/t3, and t#{176}/17.They suggested that sterility was due to arrest of the spermatozoa at the utero-tubal junction, so that the spermatozoa never reached the site of fertilization. Bennett and Dunn (1967), working with sterile t9/t12 and t#{176}/V”36 males, reported that spermatozoa did reach the oviduct but usu-ally in smaller numbers than after matings with fertile males. They concluded that some spermatozoa of sterile males reached the eggs, but these spermatozoa were incapable of ef-fecting fertilization. Although both groups of workers used essentially the same procedure for countin