Fig. 1.

Isolation of high and low quality spermatozoa through Percoll density gradients. A, The ejaculate is placed over a discontinuous Percoll gradient as shown. High quality spermatozoa have a greater density than low quality cells. B, Phase contrast image of intact spermatozoa obtained from either the high- (lower) or low- (upper) quality Percoll fractions. Black arrows indicate amorphous heads, white arrow indicates normal morphology. C, Direct contrast image of nuclei obtained following CTAB detergent treatment from high- (lower) or low- (upper) quality human spermatozoa. Scale bar = 5 μm.