Increasing evidence points to the importance of the carbohydrate moieties of membrane glycoconjugates in cellular interaction and regulation, such as embryogenesis, inflammation and tumour invasion (Jones, 1989; Opdenakker et al., 1993; Sharon & Lis, 1993). These interactions can be transitory or permanent and are mediated by different molecules, such as cell adhesion receptors (Edelman, 1988), ectoenzymes (Macek & Shur, 1988) or carbohydrate binding proteins (Barondes, 1991; Sinowatz et al., 1991). An example of cell-cell interaction and communication involving a protein-carbohydrate recognition systems is the interaction between sperm and egg at fertilization (Saling, 1989, 199 1; Wassarman, 1992). Remarkably, this carbohydrate-protein interaction has been conserved in the process of fertilization throughout the whole evolutionary scale (Dale, 1991). In mammals, several sugars have been shown to inhibit sperm-zona pellucida interaction. In particular, fucoidan, an algal heteropolysaccharide composed of sulfated L-fucose, and dextran sulfate are potent inhibitors of the binding of spermatozoa from a wide variety of animal species, ranging from lower animals to mammals, to their homologous oocyte’s external coat (Ahuja, 1982; Jones & Williams, 1990; Calvete et al., 1992). Other sulfated polysaccharides (i.e. chondroitin sulfate A and C and heparin) are unable to block this interaction, however (Peterson et al., 1984). The nomenclature used throughout this review

Carbohydrate-and heparin-binding proteins in mammalian fertilization.

Human epididymal spermatozoa taken from caput, corpus, and cauda were investigated to determine their fertilizing capacity (22 epididymides from 11 patients who had undergone orchidectomy because of prostatic cancer). The following functions, which have been reported to correlate positively with the fertilization rate, were determined: motility and progressive motility, chromatin condensation (assessed by aniline blue staining), acrosin activity, and induction of acrosome reaction by low temperature. In addition, stimulation of motility by pentoxifylline and phosphatidylcholine was examined. The results showed that motility, progressive motility, normal chromatin condensation, and inducible acrosome reaction increased from the caput to the cauda epididymidis, whereas acrosin activity was normal in all sections. Stimulation of progressive motility, especially that of caput spermatozoa, could be achieved by both pentoxifylline and phosphatidylcholine, the latter being definitely superior. In conclusion, our study confirmed that human spermatozoa in physiological status undergo several steps of maturation during the epididymal transit. Stimulation of sperm motility by phosphatidylcholine may be helpful for patients in whom epididymal spermatozoa are used for assisted reproduction

Function of human epididymal spermatozoa.

The effect of in vitro capacitation (events that occur before the acrosome reaction) on the acrosomal enzymes of human spermatozoa was determined. Capacitation of human spermatozoa was assessed by their ability to penetrate denuded hamster oocytes. The activities of a number of enzymes commonly associated with the sperm acrosome, including nonzymogen acrosin, proacrosin, inhibitor-bound acrosin, hyaluronidase, acid phosphatase, beta-glucuronidase, beta-glucosidase, beta-N-acetylglucosaminidase, beta-galactosidase and beta-N-acetylgalactosaminidase were assessed. With the exception of acid phosphatase, no alteration in enzyme activity occurred after 4 h of incubating the spermatozoa under capacitation conditions although gamete fusion took place. The acid phosphatase levels decreased twofold, presumably due to the loss of seminal (prostatic acid phosphatase that loosely adheres to spermatozoa. After 8 h of capacitation, a large decrease in sperm enzyme levels took place only in the case of hyaluronidase, although small decreases were also noted in total acrosin, proacrosin and inhibited acrosin. No new electrophoretically migrating forms of acrosin were observed. Decreases in total acrosin and proacrosin, but not in inhibited acrosin, also occurred when spermatozoa were incubated under noncapacitating conditions for 8 h, indicating that capacitation may specifically cause the release of some acrosin inhibitor from human spermatozoa. It is concluded that, with the possible exception of hyaluronidase, the in vitro capacitation of human spermatozoa does not cause a major change in its acrosomal enzyme content so that these hydrolases are fully present before the acrosome reaction takes place during gamete fusion. Serum albumin appears to protect against the loss of some of these enzymes since the activity of several glycosidases was significantly reduced when the spermatozoa were incubated for 8 h in human serum albumin-free medium.

/pdf/acrosomal-enzymes-of-human-spermatozoa-before-and-after-in-3xz6jb9ykj.pdf

Acrosomal Enzymes of Human Spermatozoa Before and After in Vitro Capacitation

I. Physiology of Male Reproduction.- 1. Hormonal regulation of testicular function.- 2. Inhibin: new gonadal hormone.- 3. Morphological features of the epididymis: possible significance in male contraception.- 4. Regulatory physiology of male accessory organs.- 5. Methods for evaluating contraceptive techniques.- II. Hormonal Contraception.- 6. Inhibition of male reproductive processes with an LH-RH agonist.- 7. LH-RH agonists: inhibition of testicular functions and possible clinical applications.- 8. Exogenous androgens: their potential for reversible contraception.- 9. Androgen-progestin combinations: clinical trials.- 10. Antiandrogens: basic concepts and clinical trials.- III. Biochemical Contraception.- 11. ?-Chlorohydrin: review of a model posttesticular antifertility agent.- 12. The contraceptive effect of 6-chloro-6-deoxysugars in the male.- 13. Interference with spermatozoal motility.- 14. Interference with spermatozoa capacitation.- 15. Contraception by acrosomal proteinase inhibitors.- IV. Surgical Contraception.- 16. Vasectomy: an anatomic, physiologic, and surgical review.- 17. Evaluation of male sterilization.- 18. Immunological consequences of vasectomy.- V. Immune and Physical Methods of Contraception.- 19. Immunologic approach to regulation of fertility in the male.- 20. Male fertility regulation by means of ultrasound.

Regulation of male fertility

Fertilization consists of a sequence of complex events which culminates in the fusion of the genetic information provided by two parent cells, thus leading to the formation of a new individuum. The male gamete develops in the testis, acquires forward motility and fertilizing capacity during maturation in the epididymis, and after capacitation undergoes the acrosome reaction in the female reproductive tract. The female gamete matures in the cyclically developing follicles and, by the time of ovulation, reaches a quiescent stage at metaphase II of meiosis. Gamete fusion occurs in the distal tube, and involves a series of modifications on the egg surface and its investments, intended to protect the developing embryo from polyspermy.

Molecular events leading to fertilization--a review.

Reversible attachment and localization of the acid-stable seminal plasma acrosin-trypsin inhibitors on boar spermatozoa as revealed by the indirect immunofluorescent staining technique.

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Reversible attachment and localization of the acid-stable seminal plasma acrosin-trypsin inhibitors on boar spermatozoa as revealed by the indirect immunofluorescent staining technique.