Comparison of Bovine Sperm Capacitation Systems for Ability of Sperm to Penetrate Zona-Free Hamster Oocytes and Bovine Oocytes Matured In Vitro

Abstract

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 oocytes at 37°C for 3 h or with bovine cumulus-enclosed oocytes matured in vitro for 8 h at 37 or 39°C. Bovine oocytes were transferred to fertilization medium and incubated for 72 h at 37 or 39°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%). Penetration of bovine cumulus-enclosed oocytes matured in vitro at 37°C was highest with heparin (48.1%), followed by TEST-yolk (35.0%), calcium-free Tyrode's (32.5%), and follicular fluid (26.4%). Sperm capacitation with heparin, assayed by penetration of bovine oocytes at 39% was better at 39°C (77.1%) than at 37°C (46.1%). However, penetration rates in calcium-free Tyrode's and TEST-yolk were higher at 37°C. The capacitation system with heparin at 39°C and bovine oocytes was best followed by the systems using TEST-yolk and calcium-free Tyrode's at 37°C. © 1995, American Dairy Science Association. All rights reserved.