A glimpse at sperm function in vivo: sperm transport and epithelial interaction in the female reproductive tract.

The process of sperm transport in the female reproductive tract is more than simply a migration of spermatozoa from the site of insemination to the site of fertilization. Rather, it is a complex and dynamic continuum that encompasses phases of sperm distribution within the tract, the accumulation of spermatozoa in reservoirs, the modulation of sperm physiology and acquisition of fertilization competence, the ascent of competent spermatozoa to the site of fertilization, and the elimination of the non-fertilizing sperm population. The dynamic interactions that occur between functional spermatozoa and the luminal fluids and epithelial surfaces of the female genital tract during transit and storage enhance sperm survival and regulate sperm function in the female. The universal nature of this interaction highlights it as a key component of the sperm transport process.