Chemotactic responsiveness of human spermatozoa to follicular fluid is enhanced by capacitation but is impaired in dyspermic semen

Purpose: Our purpose was to study the chemotactic responsiveness of human s permatozoa from normal and pathological semen samples to follicular fluid ( FF), as well as the effect exerted by capacitation on sperm chemotaxis. Methods: The chemotactic responsiveness of human spermatozoa to FF was test ed by an accumulation assay chamber in which they were allowed to migrate t hrough a microporous membrane and accumulate in a compartment filled with F F or control medium. The percentage of cells with hyperactivated motility a mong migrated sperm was objectively assessed by CASA and its relationship t o the accumulation rate was studied. Single FFs were rested with single nor mospermic or dyspermic semen samples; the same FF was tested with different semen specimens. The influence of capacitation onto the chemotactic respon siveness to FF was investigated by comparing the accumulation rate of sperm atozoa from normal and pathological samples after incubation under capacita ting conditions for I or 6 hr. Results: Some FFs ("active" FFs) effectively attracted human spermatozoa fr om normospermic samples lip to a dilution factor of 1:500 (v:v) with contro l medium. A wide range of responses was observed when the same FF was teste d with different normal semen samples. A longer time under capacitating con ditions increased both the chemotactic responsiveness of normal semen and i ts ability to undergo the acrosome reaction (AR) in response to A23187. Pat hological semen had an impaired chemotactic responsiveness to "active" FF t hat was not enhanced by increasing the time spent under capacitating condit ions. Dyspermic semen was also less responsive to A23187, a finding suggest ing incomplete capacitation. Conclusions: Chemotactic responsiveness to FF is acquired in parallel to or as part of the the capacitation process. Dyspermic semen samples have an i mpaired capacity to achieve both capacitation and chemotactic responsivenes s to follicular factors.