Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2006 / Cells living under aerobic conditions constantly face the oxygen paradox i.e. oxygen is indispensable for supporting life; however, its metabolites such as reactive oxygen species (ROS) can modify cell function. Oxidative stress (OS) arises as a consequence of excessive ROS production and/or impaired antioxidant defence mechanisms. Environmental and physiological factors have been implicated in poor sperm function. Excessive ROS generation results in oxidative damage and consequently decreased sperm function. The objectives of this study are threefold: (i) To measure the production of O 2 -. by sperm by means of flow cytometry. (ii) To determine effects of O2 -. on sperm motility and viability in the presence or absence of commercially available scavengers and RPO. (iii) To determine effects of O2 -. on selective apoptotic markers in ejaculated sperm in the presence of absence of commercially available scavengers and RPO. In the first part of the study, suitable solvents were investigated in order to introduce RPO (because of its hydrophobic nature) as a possible scavenger of ROS in human spermatozoa. Secondly, the O2 -. donor; 2, 3-dimetoxy-1-naphthoquinone (DMNQ) (2.5~M-100~M, 60 min.) was added to normozoospermic post swim-up samples in the absence or presence of Mn(lIl)TMPyP (50~M) or SOD (501U) or RPO at 0.1% and 0.5%. CASA was used to analyse motility parameters, while FACS was used to determine viability (PI, 1mM, 15 min.) and O2 -. levels (DHE, 30~M, 15min.).