[Show abstract][Hide abstract] ABSTRACT: A body of evidence indicates that morphologically abnormal human spermatozoa may exhibit impaired ability to fertilize. Yet teratospermia has widely varying etiologies, including associations with varicoceles, following fever, cigarette smoking, and exposure to polychlorinated biphenyls. Abnormalities of sperm shape in mice have also been shown to be associated with autosomal gene mutations. These varying causes of teratospermia could have different molecular consequences reflected in altered sperm function. We studied the ability of morphologically abnormal human sperm to penetrate zona-free hamster eggs as a measure of their ability to undergo an acrosome reaction and gamete membrane fusion. Motile sperm from ejaculates containing 15% normal sperm or less, as judged by World Health Organization (1999) criteria, were recovered by ISolate density centrifugation and capacitated by overnight incubation. Zona-free hamster eggs were inseminated with 1 x 10(6) motile capacitated cells and scored for sperm penetration after 3 hours of coincubation. A significant trend was found between the percent of abnormal spermatozoa within the ejaculate and impaired egg-penetrating ability, reflected in the percent of eggs penetrated, the number of penetrating sperm per egg, and the number of sperm adherent to the oolemma. Because only acrosome-reacted human spermatozoa adhere to the oolemma, these results support the notion that abnormally shaped sperm may exhibit an impaired ability to undergo an acrosome reaction. A correlation was also noted between the loss of motility of sperm following overnight incubation and impairment of their ability to undergo gamete membrane fusion. These results confirm prior findings at the level of the zona pellucida that abnormally shaped sperm exhibit functional abnormalities. However, a wide variation was observed between men in the behavior of such sperm, including occasionally high rates of egg penetration. These observations suggest that assessment of morphology may be an unreliable measure, for the individual, of sperm fertilizing ability and emphasize that sperm function testing is an important part of the evaluation of teratospermia.
Preview · Article · May 2007 · Journal of Andrology
[Show abstract][Hide abstract] ABSTRACT: In clinical studies of the ability of capacitated human sperm to penetrate zona-free hamster eggs, we have previously observed that the ratio of oolemmal adherent to penetrating sperm varied between men. Sperm incorporation did not occur immediately following gamete adhesion and not all adherent sperm penetrated the egg. To further investigate this phenomenon, comparisons were made of the kinetics of gamete adhesion, membrane fusion, and sperm incorporation of capacitated mouse and human spermatozoa by zona-free hamster eggs and of mouse sperm by zona-free mouse and hamster eggs. Eggs were inseminated with either capacitated human or mouse sperm or combinations of both, washed out of sperm suspension after initial gamete adherence, and further incubated in sperm-free medium. Gamete membrane fusion was judged by dye transfer of Hoechst 33342 and sperm entry of the cortical ooplasm by observation of expanded sperm heads within acridine orange stained eggs. Oolemmal adherent mouse and human sperm fused with and penetrated zona-free hamster eggs at different times whether eggs were inseminated in parallel or with combinations of sperm of both species. Oolemmal adherent mouse sperm penetrated zona-free hamster eggs prior to their penetration of zona-free mouse eggs. Ultrastructural studies of zona-free human eggs inseminated with human sperm confirmed prior observations with hamster eggs that only acrosome-reacted human sperm adhere to the oolemma. These results have lead us to postulate that sperm entry into the egg may occur through a "zipper" mechanism involving the ligation of local gamete receptors similar to the incorporation of target particles by phagocytes and suggest that not all oolemmal adherent human sperm are capable of being incorporated although they have undergone an acrosome reaction.
No preview · Article · Mar 1999 · Molecular Reproduction and Development
[Show abstract][Hide abstract] ABSTRACT: Clq, the first component of the classical complement pathway, is known to play roles in promoting phagocytic events, in addition to its role in activation of complement. Although the molecular events in fertilization leading to the entrance of the spermatozoan into the egg are not well understood, ultrastructural observations suggest that the process is quasi-phagocytic in nature. There is increasing evidence that complement components might play roles in fertilization. Previously, we have shown that C1q promoted the agglutination of capacitated human sperm as well as their adhesion to zona-free hamster eggs. In the present experiments, human spermatozoa were solubilized and, following their phase separation in Triton X-114, subject to 1-D polyacrylamide gel electrophoresis and immunoblotting for the presence of C1q receptors. Both gC1q-R and cC1q-R were detected. In addition, the ability of C1q to promote sperm agglutination was shown to be dependent upon capacitation, suggesting the increased expression of C1q receptors during this process.
No preview · Article · May 1998 · Journal of Reproductive Immunology
[Show abstract][Hide abstract] ABSTRACT: To study the effects of echistatin, a disintegrin known to block the binding of fibronectin (FN) and vitronectin to their respective integrin receptors, alpha 5 beta 1 and alpha v beta 3, on the adhesion of human spermatozoa to the oolemma of zona-free hamster eggs and their subsequent penetration.
Motile capacitated human spermatozoa and zona-free hamster eggs were coincubated in the presence of echistatin or in its absence and observed at short serial intervals. Whole mounts of these eggs, washed out of sperm suspension and stained with acridine orange, were scored for numbers of oolemmal adherent and penetrating sperm.
University Hospital laboratories.
Known fertile semen donors.
Numbers of spermatozoa adherent to the oolemma and those penetrating the oocyte.
Sperm adherence to the oolemma was reduced significantly at micromolar concentrations of echistatin, in a concentration-dependent manner. In contrast, echistatin did not inhibit the penetration of oocytes by sperm that had become adherent to the oolemma despite the presence of echistatin.
We propose that two processes occur in the binding of sperm to the oolemma, one that is echistatin sensitive and possibly involving the integrin receptors that recognize FN and vitronectin, and a second process, resistant to echistatin, that leads to gamete membrane fusion.
No preview · Article · Sep 1995 · Fertility and Sterility
[Show abstract][Hide abstract] ABSTRACT: Egg penetration rates in a modified SPA using microwells in tissue typing plates were comparable with those in a standard assay. This technique allows sperm penetrating ability to be determined using single zona-free hamster eggs and as few as 10,000 spermatozoa.
No preview · Article · Dec 1992 · Fertility and Sterility