Factors regulating mammalian sperm migration through the female reproductive tract and oocyte vestments

Abstract

Mechanisms of mammalian sperm migration through the female reproductive tract and ovum vestments are described. The perspective is biophysical as well as biochemical and morphological, and the focus is upon the role of sperm motility in these processes. Sperm forward progression is characterized as an interactive process between the the cell and its environment, and the mediation of flagellar bend propagation by the physical properties of its surroundings is described. These properties, together with flagellar beat kinematics, sperm morphology, and surface properties, determine the magnitude of the forces generated by sperm and their consequent rate of progression. Sperm interactions with the cervical mucus, the cumulus oophorus, and the zona pellucida are described. The poorly understood affinity of the sperm surface for the macromolecules of the mucus, cumulus, and zona is stressed, as is the viscoelastic structural mechanical resistance of these biopolymers to sperm motion. The kinematics and consequences of hyperactivated sperm motion are presented, with emphasis on objective characterization of such motion (as a biomarker), along with analysis of the mechanical advantage that such motion may confer on spermatozoa during egg-vestment interaction. Key words: sperm, transport, mucus, cumulus, zona pellucida, fertilization INTRODUCTIONFlagellar movement is a fundamental expression of the vitality of a sperm cell, and is essential for its reproductive function. The active mechanism of flagellar motion produces a sequence of principal and reverse bends [Gibbons and Gibbons, 1974; Woolley, 19771. These can have varying degrees of curvature and can be initiated and propagated along the flagellum at different rates. Flagellar bending results in a distribution of local forces and torques against the surrounding fluid. In accordance with Newton's Third Law, these are resisted by equal and opposite local forces and torques. In order to satisfy Newton's Second Law, the summation of the local local external forces and torques over the sperm head and tail must be zero. As a consequence, there Received November 8, 1988; accepted November 17, 1988. Address reprint requests to David F. Katz In a general biophysical sense, mammalian sperm swim optimally; the principles of hydrodynamics and optimal control theory demonstrate that the smooth flagellar traveling waves, commonly seen in low-viscosity media, tend to maximize the sperm's propulsive velocity with respect to the hydrodynamic power output (Pironneau and Katz, 1974). Mammalian sperm must use their swimming ability to reach the oocyte-cumulus complex, and the forces due to flagellar motion assist them in penetrating the egg vestments to reach the oolemma.Our studies of these processes are hampered by their complexity and by apparent variation among species. Some of this biological variation is real; for example, the site of semen deposition may be the vagina, cervix, or uterus. These environments differ not only with respect to their distance from the site of ferti...

New Technique, Using a Portable CO2 Incubator, for the Production of In Vitro Fertilized Egyptian Buffalo Embryos.

“…Oocytes with several layers of cumulus cells had a significantly higher percentage of cleavage and transferable embryos. Similar results were previously recorded in cattle [7,24,25]. Cumulus cells improve the fertilization in cattle by providing a capacitation-inducing mechanism, and facilitating the interaction between capacitated spermatozoa and the zona pellucida surface [6,7,26].…”

FSCB phosphorylation in mouse spermatozoa capacitation

“…Spermatozoa capacitation is characterized by acrosome reaction and spermatozoa hyperactivation (19), as well as fast, violent, whipping locomotion of the spermatozoa tail. Blazak et al (20) asserted that quantitative analysis of spermatozoa motility and velocity is crucial for determining the deleterious effects in the reproductive system, and that the most sensitive measures are the percentage of motile cells, mean spermatozoa swimming speed, and linearity (LIN), as reported for rodents and humans (21,22).…”

Motility Stimulant Effects of Prostasome Inclusion in Swim-Up Medium on Cryopreserved Human Spermatozoa

“…Even if endocrinological and functional characteristics of semen are normal, men with immotile spermatozoa are infertile. Motility may not be necessary for sperm-zona pellucida binding [14] or for penetration of the investment-free oocyte [20], but sperm motility has been considered compulsory for the penetration of cervical mucus, the movement through the female genital tract, and the entering through the oocyte investments [7].…”