IMPAIRED TRANSPORT AND FERTILIZATION INVIVO OF CALCIUM-TREATED SPERMATOZOA FROM +/+ OR CONGENIC TW32/+MICE

To determine whether calcium alters processes important for fertilization in vivo, mouse (+/+) spermatozoa were incubated in medium with 1.0-1.7 mM calcium prior to artificial insemination (AI) into the cervix of hormonally primed females. Spermatozoa from congenic t(w32)/+ mice were also tested because their flagella are hypersensitive to calcium. As a control, spermatozoa were incubated in calcium-deficient medium prior to AI. Spermatozoa from mice of both genotypes incubated in calcium-containing medium fertilized significantly fewer eggs after Al than did spermatozoa incubated in calcium-deficient medium. In addition, calcium-treated spermatozoa from t(w32)/+ mice fertilized significantly fewer eggs than calcium-treated +/+ spermatozoa. Pretreatment with calcium also reduced the number of spermatozoa in the oviducts 0.5-4.5 h after AI, and the oviducts of females inseminated with calcium-treated spermatozoa from t(w32)/+ MiCe contained significantly fewer spermatozoa than those of females inseminated with calcium-treated +/+ spermatozoa. These results suggest that preincubation in millimolar levels of calcium changes the physiology of epididymal spermatozoa in such a way as to impair sperm transport to the oviduct and fertilization in vivo.