Effect of various hexoses on sperm capacitation and penetration of rat eggs in vitro

Fertilization of rat eggs in vitro could not be achieved when epididymal spermatozoa were preincubated and eggs in clots incubated in a chemically defined medium without D-glucose. Very high proportions (84-100%) of eggs examined were undergoing fertilization when 2.78-8.34 mM-D-glucose were included in the medium. The substitution of D-fructose or D-galactose for D-glucose resulted in very poor penetration rates (0-4%), but D-mannose was effective for fertilization (59-99% penetration). Incubations for sperm capacitation and egg fertilization in different media containing the various hexoses showed that rat epididymal spermatozoa could be partly capacitated without hexose, that D-glucose, D-mannose or D-galactose but not D-fructose is effective for sperm capacitation and that only D-glucose and D-mannose supported penetration of eggs in vitro.