The spermatozoa of most invertebrates (e.g., sea urchins) and nonmammalian vertebrates (e.g., fishes and amphibians) have full capacity to fertilize eggs upon leaving the testis. Testicular spermatozoa of mammals, on the other hand, do not possess the ability to do so. Their fertilizing capacity develops as they pass through the epididymis (Young, 1931; Nishikawa and Waide, 1952; Blandau and Rumery, 1964; Bedford, 1966; Orgebin-Crist, 1967). This process, apparently “unique” to mammals, is referred to as the epididymal maturation of spermatozoa. Even after their maturation, however, spermatozoa require an additional phase of maturation or capacitation within the female genital tract before they are able to fertilize eggs (Austin, 1951, 1952; Chang, 1951a). Thus, epididymal maturation and capacitation are two extra steps that mammaliam spermatozoa must take before they can effect fertilization. In this chapter, I will discuss how mammalian spermatozoa prepare themselves for fertilization and how the spermatozoa and eggs interact during fertilization. The process and mechanisms of sperm transport in the female genital tract will not be dealt with extensively here. Readers are referred to Bishop (1961, 1969), Blandau (1969), Bedford (1970b, 1972b), Thibault (1972, 1973a), Zamboni (1972), Blandau and Gaddum-Rosse (1974), Hafez and Thibault (1975), Overstreet and Katz (1977), Overstreet and Cooper (1978, 1979b), Overstreet et al. (1978), Shalgi and Kraicer(1978), Cooper et al. (1979) and Hunter (1975, 1980). The rejection or elimination of extra spermatozoa by the fertilized egg, one of the most fascinating events in fertilization, will not be discussed here. Instead, readers are referred to the chapter by Dr. Wolf in this volume. The physiology of egg activation has been described and discussed to some extent by Gwatkin (1977) and Yanagimachi (1978a). There are numerous reviews dealing with general aspects of mammalian fertilization. The following are recommended to aid in grasping the outline of mammalian fertilization: Austin and Bishop (1957), Austin and Walton (1960), Austin (1961, 1968), Blandau (1961), Piko (1969), Thibault (1969), Bedford (1970a,b, 1972b), Gwatkin (1976, 1977), Yanagimachi (1977, 1978a), Bedford and Cooper (1978) and Hunter (1980).

Mechanisms of Fertilization in Mammals

Mammalian sperm-egg interaction: Identification of a glycoprotein in mouse egg zonae pellucidae possessing receptor activity for sperm

We describe two methods for detecting acrosome reactions of human sperm at the light microscopic level. The techniques include the use of a supravital stain to detect dead sperm in order to differentiate between “physiological” and “degenerative” acrosome reactions. Sperm are incubated with the supravital stain Hoechst 33258 (a fluorescent DNA-binding dye with limited membrane permeability), washed, suspended in 95% ethanol for fixation and permeabilization, and dried onto slides. The sperm are then labeled either by indirect immunofluorescence using rabbit anti-human sperm antiserum or with fluoresceinated Pisum sativum agglutinin (PSA). Both probes intensely label the acrosomal region of acrosome-intact sperm. Electron microscopy revealed the major site of PSA binding to be the acrosomal contents. Acrosome-reacted sperm have diminished acrosomal labeling by both probes; sperm with nuclei labeled by Hoechst stain are considered nonviable, and are excluded from the assay. Both assays are rapid, give similar results, and detect an increase in acrosome reactions following exposure to the ionophore A23187.

Two simple methods for detecting acrosome‐reacted human sperm

Fructose transporter in human spermatozoa and small intestine is GLUT5.

Lipid composition and thermotropic phase behavior of boar, bull, stallion, and rooster sperm membranes.

A variety of treatment procedures was utilized to identify the origin and composition of the vesicles formed during the acrosome reaction of boar spermatozoa. Whether the acrosome reaction occurred spontaneously or was induced chemically the vesicles were hybrid vesicles composed of roughly equal proportions of plasma and outer acrosomal membranes.

Direct evidence for formation of hybrid vesicles by fusion of plasma and outer acrosomal membranes during the acrosome reaction in boar spermatozoa

Freshly ejaculated, noncapacitated boar sperm bind rapidly and in large numbers to pig egg zona pellucida in vitro. In the present study, the number of sperm bound decreased sharply when sperm motility was lowered by energy poisons or by reducing the temperature. Highly motile sperm from humans, guinea pigs, and rats, added at concentrations ten times higher than control sperm, did not bind to the porcine zona. At the same high concentration, a small number of hamster and bull sperm bound to the zona. Binding of boar sperm to the zona pellucida was blocked almost completely by diluted whole antiserum to sperm plasma membranes and by univalent (Fab) antibody to these membranes. When antibody to sperm plasma membrane was first absorbed with plasma membrane vesicles, sperm binding was not inhibited. These results provide direct evidence for the existence of sperm plasma membrane receptors for the zona pellucida of the pig.

http://science.sciencemag.org/content/sci/207/4426/73.full.pdf

Sperm-egg interaction: evidence for boar sperm plasma membrane receptors for porcine zona pellucida.

A method for isolation of plasma membrane vesicles from human and boar spermatozoa using nitrogen cavitation is described. The purity of the preparations were assessed by electron microscopy, marker enzyme assay and the sedimentation characteristics of fused plasma membrane-acrosomal membrane vesicles in sucrose gradients. PAGE-SDS profiles of plasma membrane polypeptides from boar spermatozoa were significantly different from those of human spermatozoa. Differences in electrophoretic profiles of polypeptides from different regions of the spermatozooon were also observed.

Isolation and Characterization of Membrane Vesicles from Human and Boar Spermatozoa: Methods Using Nitrogen Cavitation and Ionophore Induced Vesiculation

Quantitative electron microscopy is used to provide new information regarding the purity and the amounts of plasma membrane originating from various regions of the surface of the boar spermatozoon when such membranes are prepared by nitrogen cavitation and sucrose density centrifugation. These data show that the plasma membranes originate primarily from the head of the spermatozoon; they also show that contamination of these plasma membranes by acrosomal and mitochondrial membranes is negligible. Immunolocalization, using plasma membrane vesicles and divalent IgG directed against plasma membrane antigens, shows that plasma membrane vesicles bind extensively to intact sperm plasma membranes but rarely bind to the outer acrosomal membrane. These new data, taken together with that which has been previously reported, indicate that means for obtaining undamaged, highly purified

/pdf/evaluation-of-the-purity-of-boar-sperm-plasma-membranes-31rfavlpi4.pdf

Evaluation of the Purity of Boar Sperm Plasma Membranes Prepared by Nitrogen Cavitation

https://www.fertstert.org/article/S0015-0282(16)44121-X/pdf

Matthew Freund

Papers

Direct evidence for formation of hybrid vesicles by fusion of plasma and outer acrosomal membranes during the acrosome reaction in boar spermatozoa

Sperm-egg interaction: evidence for boar sperm plasma membrane receptors for porcine zona pellucida.

Isolation and Characterization of Membrane Vesicles from Human and Boar Spermatozoa: Methods Using Nitrogen Cavitation and Ionophore Induced Vesiculation

Evaluation of the Purity of Boar Sperm Plasma Membranes Prepared by Nitrogen Cavitation

Morphologic characteristics of the chemically induced acrosome reaction in human spermatozoa.