Polyethylene glycol-induced attachment of human spermatozoa to zona-free rat ova in vitro.

When human spermatozoa are incubated with zona-free ova in the presence of polyethylene glycol (PEG), the spermatozoa attach to the ova. Although the binding occurs when bovine serum albumin (BSA) is omitted from the incubation medium, the spermatozoa are better maintained and bind in higher numbers in the presence of both PEG and BSA. No spermatozoa bind to zona-intact ova or to zona-free ova in the absence of PEG. The number of spermatozoa bound to ova is dependent on the concentration of PEG (optimum between 10 and 15% w/v), time of incubation (increases linearly) and concentration of spermatozoa (increases linearly).