Secreted proteins of the oviduct

During late follicular development and estrus, the mammalian oviduct underg oes specific physiological and biochemical modifications which contribute t o an optimization of the microenvironment for fertilization and early cleav age-stage embryonic development. These changes appear to be hormonally regu lated by ovarian steroids, most importantly, estrogen. The hundreds of macr omolecules found within the oviductal lumen are contributed by selective se rum transudation and active biosynthesis and secretion from nonciliated epi thelial cells. Recent studies have indicated temporal and regional (infundi bulum, ampulla and isthmus) differences in steady-state levels of specific mRNAs and in de novo protein synthesis and secretion by the oviduct. One pr otein synthesized de novo, the estrogen-dependent oviductal secretory glyco protein (OSP), has been shown to be unique to the oviduct and is conserved across a number of mammalian species, This protein associates with the zona pellucida, perivitelline space and vitelline or blastomere membrane of ovu lated eggs and preimplantation embryos. OSPs have been shown to enhance spe rm binding and penetration in oocytes and may regulate development in early preimplantation embryos. Other regulatory molecules, protease inhibitors, growth factors, cytokines, binding proteins, enzymes and immunoglobulins ha ve been identified in the oviductal microenvironment. The identification an d potential roles for oviduct-secreted proteins will be reviewed and discus sed, Current research focuses on continued identification and characterizat ion of specific oviductal proteins and a determination of the molecular bas is of their interactions with the oocyte, sperm or embryo. Copyright (C) 2000 S. Karger AG, Basel.