Role of epididymal secretory proteins in sperm maturation with particular reference to the boar

This review considers the role of proteins secreted by the epididymis on po st-testicular sperm maturation and storage. Two-dimensional gels show that 150 to 200 proteins are secreted into the epididymal lumen. Most are secret ed in relatively small amounts; in rams, for example, fewer than ten contri bute 90% of the total secretion and only two contribute 52% of the total pr otein secreted. Most of the proteins are confined to specific regions of th e epididymis. The changing pattern of protein secretion along the epididymi s corresponds to change in surface protein on spermatozoa, but no epididyma l proteins have been identified that appear to be directly involved in modi fying the sperm membrane. Most of the major proteins that have been identif ied seem to be playing a homeostatic role in maintaining the epididymal mil ieu for spermatozoa.