COMPARISON OF BOVINE SPERM CAPACITATION SYSTEMS FOR ABILITY OF SPERM TO PENETRATE ZONA-FREE HAMSTER OOCYTES AND BOVINE OOCYTES MATURED IN-VITRO

Sperm from the same ejaculate were capacitated in calcium-free Tyrode' s, modified Tyrode's with bovine follicular fluid or heparin, and TEST -yolk. Capacitated sperm were coincubated with zona-free hamster oocyt es at 37-degrees-C for 3 h or with bovine cumulus-enclosed oocytes mat ured in vitro for 8 h at 37 or 39-degrees-C. Bovine oocytes were trans ferred to fertilization medium and incubated for 72 h at 37 or 39-degr ees-C. Penetration of zona-free hamster oocytes was highest in calcium -free Tyrode's (53.7%), followed by Tyrode's with follicular fluid (50 .6%), TEST-yolk (48.6%), and Tyrode's with heparin (34.2%). Penetratio n of bovine cumulus-enclosed oocytes matured in vitro at 37-degrees-C was highest with heparin (48.1%), followed by TEST-yolk (35.0%), calci um-free Tyrode's (32.5%), and follicular fluid (26.4%). Sperm capacita tion with heparin, assayed by penetration of bovine oocytes at 39-degr ees-C, was better at 39-degrees-C (77.1%) than at 37-degrees-C (46.1%) . However, penetration rates in calcium-free Tyrode's and TEST-yolk we re higher at 37-degrees-C. The capacitation system with heparin at 39- degrees-C and bovine oocytes was best followed by the systems using TE ST-yolk and calcium-free Tyrode's at 37-degrees-C.