EFFECT OF CULTURE, INCUBATION AND ACROSOME REACTION OF FRESH AND FROZEN-THAWED RAM SPERMATOZOA FOR IN-VITRO FERTILIZATION AND INTRACYTOPLASMIC SPERM INJECTION

This study evaluated different sperm treatments for fertilization of s heep oocytes by intracytoplasmic sperm injection (ICSI) and in vitro f ertilization (IVF). In Experiment 1, fresh and frozen semen was separa ted by Percoll centrifugation and incubated at 30 degrees C or 39 degr ees C in HSOF or BSOF medium for Ih before use for IVF or ICSI, For IV F, oocytes were inseminated and incubated with sperm for 30 min, 4 h a nd 19 h. Sperm were assessed for acrosome integrity after Percoll cent rifugation and 1 h incubation, and those used for IVF were assessed af ter each period of exposure to the oocytes. Fertilization rates after ICSI were higher for fresh than for frozen-thawed sperm and were highe st 19 h after IVF with fresh or frozen-thawed sperm in the presence of HSOF at 30 degrees C. In Experiment 2, fresh semen was separated by P ercoll centrifugation and incubated for 5 h in HSOF, and the acrosome reaction was induced with lysophosphatidylcholine. Acrosome integrity was then assessed. Fertilization rates after ICSI were similar for acr osome-reacted and control spermatozoa. These results suggest that indu ction of the acrosome reaction in spermatozoa before ICSI is unnecessa ry, whereas a capacitating treatment of spermatozoa is required before IVF.