Delta 5-3-beta-hydroxysteroid dehydrogenase activity in rat oviduct and implications of oviductal steroidogenesis

Tubal factor in infertility is about one third. As part of an ongoing study of the mammalian oviduct the rat oviduct was serialised into 66 zones for the characterisation of 3 beta-hydroxysteroid dehydrogenase activity using substrates dehydroepiandosterone (DHA), pregnenolone and testosterone. Reactivity was quantified from 1-5 and was present in some of the preampullary zones of the rat oviduct in stromal and epithelial cells and completely absent in isthmic zones. Ultrastructural analysis of oviduct ampullaryisthmic zone 33 showed a probable epithelial steroidogenic cell with considerable amounts of smooth endoplasmic reticulum and hooded and circumnuclear mitochondria. The localisation of sterol dehydrogenase activity in some zones of the preampullary-ampullary segments in the rat oviduct opens up potentialities for the study of steroidogenesis in the mammalian oviduct. If the mammalian oviduct produces considerable amounts of steroids in some zones, as the histochemical activity demonstrates, then conditions such as luteinised unruptured follicle (LUF; with diagnostic peritoneal decrease in steroid concentration), steroid presence in oviductal fluid, ovulation control by the oviduct and even oocyte maturation and local steroid-peptide interactions are easily explainable. Without the zones model, it will not be possible to characterise the activity.