Effect of polyamines on fertilization of mouse ova in vitro

After a 1-hour preincubation of epididymal mouse spermatozoa at a concentration of 2 X 10(6)/ml in 0.23 mM spermine, the proportion of F1(C57BL X CBA) mouse ova fertilized after 1 and 2 hours was significantly greater than with untreated spermatozoa. Spermine also significantly increased the proportion of ova fertilized at the sub optimal sperm concentration of 2 X 10(5)/ml. The stimulatory effect was lost when the protein source in the fertilization medium was changed from human serum albumin V (HSA) to HSA crystalline. This provides indirect evidence that albumin is directly involved in the capacitation process and that the crystalline is more potent than the fraction V preparation. At equimolar concentrations, spermidine was partially and putrescine was totally inhibitory to fertilization. Mechanisms whereby spermine may affect metabolic activity or sperm-zona binding are discussed. It is suggested spermine may also be present in ovulatory fluid and therefore could potentially be involved in fertilization in vivo.