Mechanism of prolonged sperm storage and sperm survivability in hen oviduct: a review.

A unique property of the avian oviduct is to store sperm for a prolonged period. The sperm storage tubules (SST) are located in the utero-vaginal junction of the oviduct, where sperm can be stored and survived for a few weeks after insemination or natural mating. The immune system in the oviduct is essential to prevent tissue infection by various microorganisms, and it may also affect the fate and survivability of sperm in the oviduct. Anti-sperm immunoresponses including infiltration of leukocytes may be induced in the vagina of the oviduct. Sperm that will participate in fertilization may be selected by these immunoresponses. However, sperm stored in the SST may be protected from the immunoresponse by SST structures and transforming growth factor beta, whose expression is increased during sperm storage in the SST. In this review, the mechanism of sperm survivability with reference to the regulation of anti-sperm immunoresponses in hen oviduct is emphasized.