SPERM FUNCTION AND CHOICE OF PREPARATION MEDIA - COMPARISON OF PERCOLL AND ACCUDENZ DISCONTINUOUS DENSITY GRADIENTS

We compared the sperm populations prepared by Accudenz (35-65%) and Pe rcoll (40-80%) density gradients in 21 normospermic specimens (concent ration, 53.6 +/- 3.8 x 10(6) sperm/ml; motility, 44.5 +/- 3.5%). Accud enz facilitated a higher recovery of sperm and motile sperm (68.4 +/- 6.6% vs. 49.3 +/- 4.9%, P < 0.001, and 87.8 +/- 4.1% vs. 77.8 +/- 3.7% , P +/- 0.01, respectively). Sperm motility was lower in the Accudenz compared to the Percoll pellets; thus the values of total motile sperm recovered were not different (17.1 +/- 2.4 vs. 15.1 +/- 2.2 x 10(6) s perm/ml). The long-term retention of sperm motility was substantially improved in Accudenz (at 24 hours, 34.9 +/- 2.8% vs. 26.3 +/- 1.5%; 60 % vs. 40% of the initial motility, P i 0.001), and the Accudenz vs. Pe rcoll samples also exhibited a higher retention of total motile sperm (at 24 hours, 9.8 +/- 1.2 vs. 6.1 +/- 0.5 x 10(6) motile sperm/ml, P < 0.05). The sperm motility index, a multiple of velocity and motility in the sample that reflects the efficiency of the sperm population in sperm-oocyte interaction, was 75% higher in the Accudenz samples at 24 hours (3.6 +/- 0.4 vs. 2.1 +/- 0.2, mu m/second, P < 0.01). Sperm cel lular maturity by the creatine phosphokinase (CK) activity and CK-M to CK-B isoform ratio parameters (in the original samples 0.14 +/- 0.02 IU CK/100 x 10(6) Sperm and 57.9 +/- 3.7%, respectively) were improved in both the Accudenz and Percoll pellets(P < 0.001), with no differen ce between the two sperm fractions. Sperm activation status monitored by chlortetracycline fluorescence indicated that after 4 hours of incu bation the incidence of fully acrosome-reacted spermatozoa in the Accu denz versus Percoll pellets was 6.2 +/- 0.3% versus 13.1 +/- 1.0% (P < 0.001), a 100% increase in Percoll. We can conclude that Accudenz yie lds a higher concentration of motile spermatozoa, with improved retent ion of motility, velocity, and acrosomal integrity and without an incr ease of sperm with diminished cellular maturity. Thus, in sperm prepar ation for intrauterine insemination, in which the timing of ovulation and insemination frequently do not correspond, Accudenz-prepared sperm , with a better retention of motility/velocity and acrosomal integrity and with a consequential higher resistance to activation by the femal e reproductive tract, are expected to be more effective.