Sperm Storage in the Female Reproductive Tract in Birds

Abstract

The ability to store sperm in the female genital tract is frequently observed in vertebrates as well as in invertebrates. Because of the presence of a system that maintains the ejaculated sperm alive in the female reproductive tract in a variety of animals, this strategy appears to be advantageous for animal reproduction. Although the occurrence and physiological reasons for sperm storage have been reported extensively in many species, the mechanism of sperm storage in the female reproductive tract has been poorly understood until recently. In avian species, the specialized simple tubular invaginations referred to as sperm storage tubules (SSTs) are found in the oviduct as a sperm storage organ. In this review, we summarize the current understanding of the mechanism of sperm uptake into the SSTs, maintenance within it, and controlled release of the sperm from the SSTs. Since sperm storage in avian species occurs at high body temperatures (i.e., 41 C), elucidation of the mechanism for sperm storage may lead to the development of new strategies for sperm preservation at ambient temperatures, and these could be used in a myriad of applications in the field of reproduction.

Seminal Influence of the Oviduct : Mating and/or semen components induce gene expression changes in the pre-ovulatory functional sperm reservoir in poultry and pigs

“…There are several review articles published describing a small subpopulation of spermatozoa reaching the oviduct sperm reservoir (UVJ in hens and UTJ in sows) where they remain alive without being eliminated by the immune attack, while the rest of the deposited ejaculates including spermatozoa are either egressed by backflow from the female genital tract or eliminated by phagocytosis both in chicken (Bakst, 1994;Das et al, 2008;Sasanami et al, 2013) and in pig (Schuberth et al, 2008;Holt, 2011;Tienthai, 2015). Only few immune-suppressing genes have been targeted and identified in the UVJ of poultry after insemination/mating using quantitative RT-PCR (Das et al, 2006;Abdel-Mageed et al, 2008;Huang et al, 2016) or including serial analysis of gene expression in oviduct SR in turkey (Long et al, 2003).…”

“…Corresponding findings have been reported in poultry, with the release of SST-spermatozoa being slow, gradual and continuous, and without an absolute relation to the ovulation of the oocyte. Spermatozoa released from the SST are quickly transported to the infundibulum (possibly only by muscular contractions) where they can fertilize not only the newly ovulated oocyte but also the next-day oocyte (Sasanami et al, 2013). However, since each oocyte is then covered by several layers of secretions by the lower segments of the oviduct, forming the egg, the SST-spermatozoa do not leave again from the SR until the egg has been laid (Sasanami et al, 2013).…”

“…Spermatozoa released from the SST are quickly transported to the infundibulum (possibly only by muscular contractions) where they can fertilize not only the newly ovulated oocyte but also the next-day oocyte (Sasanami et al, 2013). However, since each oocyte is then covered by several layers of secretions by the lower segments of the oviduct, forming the egg, the SST-spermatozoa do not leave again from the SR until the egg has been laid (Sasanami et al, 2013). This situation is basically different in pigs (as in most mammals) since the tubal lumen is not blocked.…”

“…Lipases are also ascribed a role in sperm survival, and there is a relatively increased expression of adipose triglyceride lipase (ATGL) mRNA in the SST of AI-hens (Huang et al, 2016). As well, there is an increased mRNA expression of avidin and avidin related protein-2 (AVR2) in the SST of turkey (Long et al, 2003;Foye-Jackson et al, 2011), both related to the maintenance of spermatozoa in the oviductal sperm reservoir (for review see Sasanami et al, 2013). In pig endometrium, the mRNA expression of the cyclooxygenase-2 (COX-2) gene, which is responsible for prostaglandin synthesis, increases after intrauterine SP-infusion (O´Leary et al, 2004).…”

“…In hens, the reservoir is located in the utero-vaginal junction (UVJ), while in pigs it is present in the utero-tubal junction (UTJ). In these analogous reservoirs, functionality of the immunologically foreign spermatozoa is maintained for a couple of days in pigs or for weeks in poultry (Rodríguez-Martínez et al, 2005;Bakst, 2011;Sasanami et al, 2013), by ways yet to be fully understood.…”