Showing papers on "Sperm plasma membrane published in 1980"

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

Abstract: 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.

Interaction of Lipids with the Plasma Membrane of Sperm Cells. I. The Antifertilization Action of Cholesterol

Abstract: The inhibitory action of cholesterol-containing suspensions on fertilizing capacity in uterine-capacitated rabbit sperm cells showed a direct dependence on the concentration of sterol. Dispersion with synthetic phosphatidylcholine as a nonsonicated suspension or as liposomes did not alter this antifertilization effect. Esterification of the sterol, however, caused a complete loss of inhibitory activity. Cholesterol inhibited induction of the acrosome reaction among epididymal rat spermatozoa incubated under chemically defined conditions. Other agents with a negative effect on the acrosome reaction were seminal plasma membrane vesicles and palmitic acid. Egg lecithin-liposomes and bovine serum albumin, especially after being delipidated, facilitated it. These results corroborate the viewpoint that changes in the lipid bilayer of sperm plasma membrane significantly influence fertilizing capacity among mammalian spermatozoa.

Ultrastructural observations of boar spermatozoa penetrating zona-free hamster eggs.

Abstract: Boar spermatozoa preincubated in a modified KRB medium never penetrated zona-free hamster eggs, and no structural changes were observed in their acrosomes. The acrosome reaction was observed at the acrosomal cap region of spermatozoa preincubated for 5 h in the isolated uterus from a maturing gilt. Only acrosome-reacted spermatozoa fused with zona-free hamster eggs. Sperm-egg membrane fusion was essentially the same as that of homologous fertilization in other species; only the microvilli of the egg surrounding the postacrosomal region fused with sperm plasma membrane. The ultrastructural features of the sperm pronucleus in the hamster egg were dissimilar to those in the pig egg, indicating that some vitelline factors might be involved in the formation of the sperm pronucleus.

Antibody activities of serum and uterine fluid samples from rabbits isoimmunized against sperm fractions.

Abstract: Sperm and uterine fluid samples were collected from rabbits that had been isoimmunized systemically and were challenged locally against a sperm extract (soluble fraction of lithium diiodosalicylate extraction) and a sperm-pellet extract (soluble fraction of Nonidet NP-40 treatment of pellet remaining after LIS extraction). Antibody activity against the sperm plasma membrane was found in serum and uterine fluid samples from the sperm-extract immune rabbits, as indicated by an inhibition of sperm attachment to ova in vitro and by indirect immunofluorescent staining on unfixed sperm. A strong acrosome staining was noted with fixed sperm. These samples did not show fluorescent staining of swollen heads of sperm or react with blastocysts. The immune samples from rabbits injected with sperm-pellet extract displayed the opposite reactions. These samples did not react with the plasma membrane of sperm but the IgA antibodies of the uterine fluids caused immunofluorescent staining of the swollen heads of sperm and ...

Interaction of Lipids with the Plasma Membrane of Sperm Cells. II. Evidence of a Membrane Thermotropic Transition

Abstract: Cholesterol and phosphatidylcholine uptake from dipalmitoyl-phosphatidylcholine liposomes by rabbit spermatozoa showed a complex dependence on temperature in these experiments. At 5° and 20°C, the rate of lipid uptake correlated with temperature. However, from 20° to 37°C uptake did not evidently increase. The result is interpreted as evidence of a thermotropic transition in the sperm plasma membrane. Data are presented showing incorporation of these lipids, especially that of cholesterol, into sperm plasma membrane.

Identification of a rabbit sperm autoantigen as a Ricinus communis I receptor

Abstract: The isolated rabbit sperm plasma membrane autoantigen RSA-1 has been identified as a receptor for the lectin, Ricinus communis I (RCA). Using purified RSA-1 labeled with125 I, the autoantigen was shown to bind to RCA affinity columns and the eluted fraction bound to specific anti-RSA-1 alloantiserum immunoadsorbent columns.

Morphological observations on the binding of boar sperm to porcine zona pellucida.

Abstract: Scanning electron microscopy demonstrated that freshly ejaculated boar sperm bind in large numbers to the cumulus-free zona pellucida of porcine oocytes. Sperm were bound head-first although some portions of the flagellum occasionally made contact with the zona. Scanning microscopy also showed that sperm did not undergo an acrosome reaction or penetrate the zona after binding. Binding of boar sperm was visibly inhibited by pretreatment of the sperm by Fab antibodies to boar sperm plasma membranes. The forgoing indicate that specific receptors for the zona pellucida are present and exposed on the surface of non-capacitated boar sperm. In addition, when soluble components which were extracted from sperm by sedimentation at high speed, were preincubated with oocytes, sperm did not bind. Minor surface changes were noted after these treatments, but the zona remained intact and was not penetrated by sperm. Either this treatment inactivated sperm receptors or the outer layer of the zona, which may be the only portion of the zona containing receptors, was removed. Since binding of the sperm to the zona pellucida involved the sperm plasma membrane, we suggest that this membrane is intact when the sperm reaches the zona. Surface changes accompanying capacitation are apparently not necessary for species-specific sperm-egg binding in vitro in the pig.

Morphological changes of mouse spermatozoa in uterus as revealed by scanning and transmission electron microscopy.

Abstract: Submicroscopic alterations occurring in mouse spermatozoa during their sojourn into the female reproductive tract--as revealed by Scanning Electron Microscopy and Transmission Electron Microscopy using ruthenium red as marked for glycosaminoglycans--are described in the present investigation. The results show that the surface of the plasma membrane covering the acrosomal region of the spermatozoa found in the uterus--at different intervals of time after copulation (between 10 minutes up to 20 hrs)--are provided with an increasing number of granules and small vesicles. Some of the surface structures appear gradually leading to perforation of discrete areas of plasma membrane in regions corresponding to acrosomal areas covering the head of spermatozoa. Similarly ruthenium red preparations, show a significant decrease of glycosaminoglycans and their sialic acid moieties, which specifically precede further vesiculation and perforation of the sperm plasma membrane covering the same acrosomal regions.