“…PTX has been considered to stimulate flagellar motility by increasing sperm intracellular cAMP (Stefanovich, 1973;Garbers & Kopf, 1980;Tash & Means, 1983;Ward & Clissold, 1987) as well as by reducing sperm intracellular superoxide anion and reactive oxygen species known to damage DNA (Lopes et al, 1998;Twigg et al, 1998). In particular PTX in both in vivo and in vitro studies, appears to increase significantly beat cross frequency, curvilinear velocity, and the percentage of hyperactivated spermatozoa (Rees et al, 1990;Shen et al, 1991;Lewis et al, 1993;Moohan et al, 1993;Pang et al, 1993;Tournaye et al, 1994;Centola et al, 1995;Paul et al, 1996;Nassar et al, 1999).…”