EFFECTS OF CAFFEINE AND DBCAMP ON ZONA-PELLUCIDA PENETRATION BY EPIDIDYMAL SPERMATOZOA OF CYNOMOLGUS MONKEYS (MACACA-FASCICULARIS)

Spermatozoa mature during epididymal transit, acquiring the abilities to swim progressively, fertilize oocytes, and produce viable offspring . in this study, we investigate the capacity of spermatozoa retrieved from the midcorpus and distal cauda regions of the epididymis of the c ynomolgus monkey to penetrate homologous zona pellucida. Successful in vitro fertilization by ejaculated macaque sperm is dependent upon the addition of caffeine and dbcAMP. Therefore, the effect of these cycli c nucleotide mediators was also examined in this study. Results of spe rm motion analysis indicate no difference in baseline values (without stimulators) for any motion parameter. With the addition of caffeine a nd dbcAMP, curvilinear velocity significantly increased only for the d istal cauda sperm (P = 0.05). Amplitude of the lateral head displaceme nt was significantly increased for distal cauda sperm (P < 0.01); alth ough elevated above baseline, the increase observed after activation b y corpus sperm was significantly lower than that achieved by cauda spe rm (P < 0.05). The addition of caffeine and dbcAMP was an absolute req uirement for zona penetration by both midcorpus and distal cauda sperm . With activation, zona penetration was significantly decreased for co rpus sperm compared to cauda sperm (P < 0.001). These results suggest that cynomolgus monke)r sperm reaching the midcorpus region of the epi didymis have not completed all of the maturational changes requisite f or successful fertilization; this immaturity is evidenced by decreased sperm motion acid by impedance at the level of zona penetration. (C) 1996 Wiley-Liss, Inc.