Sperm Transport Through the Female Reproductive Tract

Abstract

Mammalian spermatozoa are highly complex specialized cells that survive a long and fascinating journey from the site of insemination to the upper third of the oviduct, where fertilization occurs. During this journey, these cells have to go through different microenvironments, which provide appropriate conditions for the occurrence of sperm capacitation and acrosome reaction (AR) in the time and place needed. These events need to occur in an extremely synchronized sequence in order to assure that fertilization takes place. The objective of this review article is to describe and analyze the various changes that spermatozoa will experience during their journey through the female genital tract and how they are influenced by the epithelium and secretions present in the cervix, endometrium and oviduct. These microenvironments will prevent the AR from occurring ahead of time as in the case of estrogenic cervical mucus or will stimulate its occurrence as in the case of progesterone, present during ovulation in oviductal fluid. In all cases the female reproductive tract will supply the conditions needed to guarantee survival, capacitation, AR and migration of spermatozoa for subsequent fusion with the oocyte. These microenvironments contain various hormones, neurotransmitters and other metabolites for which spermatozoa have specific receptors through which these substances can modulate their fertilizing potential. The study and understanding of the physiological conditions needed for gamete membrane fusion to occur is an important aspect to be considered both in basic and applied research in reproductive biology.

Ovarian sex steroid and epithelial control of immune responses in the uterus and oviduct: human and animal models

“…The oviduct and uterus serve as crucial mediators in various stages of the reproductive processes, including gamete activation and transportation, sperm capacitation, fertilization, early embryo development, and pregnancy [ 1 , 2 ]. The oviduct is also known as Fallopian tubes in humans; to maintain consistency, the term “oviduct” has been utilized for all species discussed in the present review.…”