Reactive oxygen species such as superoxide anion (O2-), hydrogen peroxide (H2O2) and hydroxy radical (OH) possess potent oxygen toxicity to cells. Superoxide dismutases (SODs) are metalloenzymes that are essential for dismutation of O2- to H2O2 and O2. SODs are important initial components in the cellular defense against oxygen toxicity since O2- can react with H2O2 to generate single oxygen and hydroxy radicals, which are even more reactive and cytotoxic than O2- or H2O2. In mammalian tissues three superoxide dismutases (SODs) designated Cu,Zn-SOD, Mn-SOD and extracellular SOD exist. These enzymes play an important role in the antioxidant defense system against superoxide anion (O2-) generated in vivo and may be involved in various pathophysiological processes including inflammation, cancer diabetes, aging and ischemia. (1) The role of superoxide anion in ovulation and luteal function was investigated the localization of Cu, Zn-SOD and Mn-SOD in rat and human ovary by immunohistochemical methods. Cu,Zn-SOD was present in granulosa cells of mature Graafian follicles and growing follicles and Mn-SOD was present in luteal cells of the corpus luteum in rat. (2) To investigate the relationship between active oxygen radical-scavenge system and ovulatory mechanism in human. Mn-SOD was found in granulosa cells and theca cells of mature follicles, luteal cells of corpus luteum and epithelial cells of fallopian tubes. Cu,Zn-SOD was localized in theca cells of mature follicles, margin of corpus luteum and epithelial cells of tubal isthmus.(ABSTRACT TRUNCATED AT 250 WORDS)