SPERM CONCENTRATION INFLUENCES FERTILIZATION AND MALE PRONUCLEAR FORMATION IN-VITRO IN PIGS

To study the effect of sperm concentration on the results of pig in vi tro fertilization (IVF), 313 oocytes recovered from oviducts of prepub ertal gilts after induction of ovulation were used. After capacitation , the number of live spermatozoa in the fertilization dishes was adjus ted to 3 x 10(5), 6 x 10(5) and 12 x 10(5) cell/ml. After 4 hours of c o-culture in TCM-199, the oocytes were pippeted to remove cumulus cell s and the excess spermatozoa around the zona pellucida, and were trans ferred to fresh TCM-199 for another 12/14 hours. The results showed th at 6 x 10(5) spermatozoa/ml is the optimum concentration for this syst em; the percentage of fertilized ova (71.6%) was not different from th e best (76.8%), that was obtained with the highest concentration, and the percentage of monospermy (62.3%) was not different from the best ( 68.1%), that was obtained with the lowest concentration. The percentag e of spermatozoa that reached the pronuclear stage increased while spe rm concentration was decreased. The percentage of spermatozoa at the d econdensed stage was decreased when the sperm concentration increased.