Ž .
Animal Reproduction Science 60–61 2000 337–348 www.elsevier.comrlocateranireprosci
A glimpse at sperm function in vivo: sperm transport and epithelial interaction in the female
reproductive tract
Mary A. Scott
Department of Population Health and Reproduction, School of Veterinary Medicine, UniÕersity of California at DaÕis, One Shields AÕe., Reproduction, DaÕis, CA 95616, USA
Abstract
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 accumula- tion 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. q
2000 Elsevier Science B.V. All rights reserved.
Keywords: Sperm; Sperm transport; Sperm storage; Uterotubal junction; Oviduct
1. Introduction
The arrival of fully mature and functionally competent spermatozoa at the site of fertilization is not a random event, but is the culmination of a concert of interactions
between sperm cells and the female reproductive tract that optimizes the likelihood of conception. These spermatozoa, which comprise only a small fraction of the inseminate,
Corresponding author. Tel.: q1-530-752-1358; fax: q1-530-752-4278. Ž
. E-mail address: mascottucdavis.edu M.A. Scott .
0378-4320r00r - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž
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have completed a long and arduous journey, during which they have surmounted the formidable anatomical barriers within the female tract and have undergone the physio-
logical changes that are required to initiate and complete fertilization. The journey begins at insemination and proceeds with a variable timetable that appears to be closely
regulated by the female. Sperm distribution and function in the female are influenced by the site of semen deposition, seminal characteristics, the anatomy of the female genital
tract, and the microenvironment of the lumen. The duration of sperm transport depends on the interval between insemination and ovulation and the functional lifespan of
spermatozoa in the female tract. Accordingly, inter-species variation in sperm transport biology likely reflects the diversity of social behaviors and mating strategies that have
evolved in the animal kingdom.
This review provides a general overview of the natural history of mammalian spermatozoa following insemination, with special emphasis on sperm–epithelium inter-
action as an integral feature of sperm function in vivo. For a more detailed examination of sperm transport, the reader should consult one or more of the many comprehensive
Ž reviews that are available in the literature e.g., Hunter, 1975; Overstreet, 1983; Hunter,
1988; Overstreet and Katz, 1990; Drobnis and Overstreet, 1992; Harper, 1994, Yanagi- .
machi, 1994 .
2. Copulatory behavior and insemination
