scholarly journals OBSERVATIONS ON SPERM PENETRATION IN THE RAT

1961 ◽  
Vol 10 (2) ◽  
pp. 275-283 ◽  
Author(s):  
Daniel G. Szollosi ◽  
Hans Ris
Keyword(s):  
Plasma Membrane ◽  
Cross Sections ◽  
Plasma Membranes ◽  
Previous Night ◽  
Egg Membrane ◽  
Sperm Plasma Membrane ◽  
Sperm Penetration ◽  
Sperm Midpiece ◽  
New Hypothesis ◽  
Structural Aspects

The structural aspects of sperm penetration in the rat egg were investigated by electron microscopy. Eggs were recovered at intervals between 8 and 10:30 A.M. from females which had mated during the previous night. The oviducts were flushed with hyaluronidase and the eggs transferred into a 2 per cent osmium tetroxide solution, buffered at pH 7.8. After fixation, the eggs were mounted individually in agar, dehydrated in ethyl alcohol, and embedded in butyl-methyl methacrylate (3:1). The sperm penetrating the egg is covered by a plasma membrane which is present only on the side facing toward the zona pellucida; no membrane is visible on the side facing toward the vitellus. The sperm plasma membrane becomes continuous with the egg plasma membrane and forms a deep fold around the entering sperm. Cross-sections through the sperm midpiece in the perivitelline space show an intact plasma membrane. At the place of entrance, the plasma membrane of the sperm appears to fuse with the egg plasma membrane. After the sperm has penetrated the vitellus, it has no plasma membrane at all. The nuclear membrane is also absent. These observations suggest a new hypothesis for sperm penetration. After the sperm has come to lie on the plasma membrane of the egg, the egg and sperm plasma membranes rupture and then fuse with one another to form a continuous cell membrane over the egg and the outer surface of the sperm. As a result the sperm comes to lie inside the vitellus, leaving its own plasma membrane incorporated into the egg membrane at the surface of the egg.

scholarly journals ROLE OF THE GAMETE MEMBRANES IN FERTILIZATION IN SACCOGLOSSUS KOWALEVSKII (ENTEROPNEUSTA)

1963 ◽  
Vol 19 (3) ◽  
pp. 501-518 ◽  
Author(s):  
Laura Hunter Colwin ◽  
Arthur L. Colwin
Keyword(s):  
Plasma Membrane ◽  
Membrane Fusion ◽  
Plasma Membranes ◽  
Sperm Nucleus ◽  
Zygote Formation ◽  
General Hypothesis ◽  
Acrosomal Vesicle ◽  
Saccoglossus Kowalevskii ◽  
Sperm Plasma Membrane

An earlier paper showed that in Saccoglossus the acrosomal tubule makes contact with the egg plasma membrane. The present paper includes evidence that the sperm and egg plasma membranes fuse to establish the single continuous zygote membrane which, consequently, is a mosaic. Contrary to the general hypothesis of Tyler, pinocytosis or phagocytosis plays no role in zygote formation. Contact between the gametes is actually between two newly exposed surfaces: in the spermatozoon, the surface was formerly the interior of the acrosomal vesicle; in the egg, it was membrane previously covered by the egg envelopes. The concept that all the events of fertilization are mediated by a fertilizin-antifertilizin reaction seems an oversimplification of events actually observed: rather, the evidence indicates that a series of specific biochemical interactions probably would be involved. Gamete membrane fusion permits sperm periacrosomal material to meet the egg cytoplasm; if an activating substance exists in the spermatozoon it probably is periacrosomal rather than acrosomal in origin. The contents of the acrosome are expended in the process of delivering the sperm plasma membrane to the egg plasma membrane. After these membranes coalesce, the sperm nucleus and other internal sperm structures move into the egg cytoplasm.

Interactions between gametes leading to fertilization: the sperm's eye view

1995 ◽  
Vol 7 (4) ◽  
pp. 927 ◽  
Author(s):  
BT Storey
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Mammalian Species ◽  
Sperm Chromatin ◽  
Peptide Backbone ◽  
Mouse Sperm ◽  
Gamete Interactions ◽  
Sperm Plasma Membrane ◽  
Sperm Penetration ◽  
Strong Candidate

Sexual reproduction requires that the gamete carrying the male-derived haploid chromatin join with the gamete carrying the female-derived haploid chromatin during fertilization to produce the diploid zygote. To accomplish this feat, the sperm must not only meet the egg, it must recognize the egg and be recognized in turn by the egg, and in the end must enter and be engulfed by the egg. In this selective overview of gamete interactions that lead to fertilization, encounters of three kinds, followed by the finale of gamete fusion, are considered from the sperm's viewpoint, with particular emphasis on the mammalian species with the mouse as the principal model. The first encounter is with the zona pellucida of the egg, to whose surface the sperm must bind. Mouse sperm appear to have four binding sites for zona ligands. Three interact with sugar moieties of the oligosaccharide chains of the mouse zona glycoprotein ZP3; the fourth binds a peptide backbone arginine. Capacitation is not required for this encounter, but is obligate for the second encounter--induction of the acrosome reaction in the bound sperm. The acrosome reaction is an exocytotic process that makes available the enzymatic machinery needed for sperm penetration the zona which is the end point of a sequence of reactions directed by intracellular signalling systems. In mouse sperm, these systems are presumed to be activated by ligands on ZP3 binding to ligand-specific sperm receptors with consequent aggregation of receptors. No receptor has been identified with certainty, nor have candidates for putative ZP3 ligands been identified. Completion of the acrosome reaction allows the sperm to penetrate the zona and, bind to the egg plasma membrane, thereby completing the third encounter. In the mouse, a 94-kDa protein appears essential for this binding. In the guinea-pig, a sperm plasma membrane protein (formerly PH-30, now fertilin), is a strong candidate for the mediator of the fusion process by which the egg engulfs the sperm. Decondensation of the sperm chromatin reverses the remarkable packing of DNA organized by sperm protamines. Mitochondrial DNA is also engulfed by the egg; the question of whether this DNA makes a small finite, or null, contribution to cytosolic inheritance is still in debate. The puzzles attending these encounters are presented as reminders of the intricacy and fascination, as well as of the vital necessity, of gamete interaction.

scholarly journals ROLE OF THE GAMETE MEMBRANES IN FERTILIZATION IN SACCOGLOSSUS KOWALEVSKII (ENTEROPNEUSTA)

1963 ◽  
Vol 19 (3) ◽  
pp. 477-500 ◽  
Author(s):  
Arthur L. Colwin ◽  
Laura Hunter Colwin
Keyword(s):  
Plasma Membrane ◽  
Osmium Tetroxide ◽  
Plasma Membranes ◽  
Previous Evidence ◽  
Egg Envelope ◽  
Saccoglossus Kowalevskii ◽  
Acrosomal Membrane ◽  
Peripheral Ring ◽  
Sperm Plasma Membrane

Previous electron microscope studies of sperm-egg association in the annelid Hydroides revealed novel aspects with respect to the acrosomal region. To determine whether these aspects were unique, a comparable study was made of a species belonging to a widely separated phylum, Hemichordata. Osmium tetroxide-fixed polyspermic material of the enteropneust, Saccoglossus, was used. The acrosomal region includes the membrane-bounded acrosome, with its large acrosomal granule and shallow adnuclear invagination, and the periacrosomal material which surrounds the acrosome except at the apex; here, the acrosomal membrane lies very close to the enclosing sperm plasma membrane. After reaching the egg envelope, the spermatozoon is activated and undergoes a series of changes: the apex dehisces and around the resulting orifice the acrosomal and sperm plasma membranes form a continuous mosaic membrane. The acrosomal granule disappears. Within 7 seconds the invagination becomes the acrosomal tubule, spans the egg envelopes, and meets the egg plasma membrane. The rest of the acrosomal vesicle everts. The periacrosomal mass changes profoundly: part becomes a fibrous core (possibly equivalent to a perforatorium); part remains as a peripheral ring. The basic pattern of structure and sperm-egg association in Saccoglossus is the same as in Hydroides. Previous evidence from four other phyla as interpreted here also indicates conformity to this pattern. The major role of the acrosome is apparently to deliver the sperm plasma membrane to the egg plasma membrane.

scholarly journals Isolation and electrophoretic characterization of the plasma membrane of sea-urchin sperm

1983 ◽  
Vol 59 (1) ◽  
pp. 13-25
Author(s):  
N.L. Cross
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Periodic Acid ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Blue Staining ◽  
Coomassie Blue Staining ◽  
Electrophoretic Patterns ◽  
Sperm Plasma Membrane

A subcellular fraction containing plasma membranes was isolated from flagella of the sperm of Strongylocentrotus purpuratus by differential centrifugation, and analysed by sodium dodecyl sulphate/polyacrylamide gel electrophoresis. Coomassie Blue staining revealed nine major bands and 14 minor species. Five bands of apparent molecular weights approximately 200 X 10(3), 149 X 10(3), 120 X 10(3), 75 X 10(3) and 59 X 10(3) also stained with periodic acid-Schiff's reagent and so are probably glycoproteins. These five components are externally exposed, as determined by lactoperoxidase-catalysed radio-iodination. Isolation of membranes from radio-iodinated sperm results in an enrichment of about tenfold in the specific activity of 125I. Comparison of the electrophoretic patterns of labelled sperm and of the membranes isolated from 125I-labelled sperm suggests that no major labelled proteins are lost during the isolation procedure, and so to this extent the membrane fraction is representative of the entire sperm plasma membrane.

The fine structure of fertilization in the fern Marsilea vestita

1978 ◽  
Vol 30 (1) ◽  
pp. 265-281
Author(s):  
D.G. Myles
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Nuclear Envelope ◽  
Plasma Membranes ◽  
Multilayered Structure ◽  
Thick Wall ◽  
Clear Space ◽  
Marsilea Vestita ◽  
Sperm Plasma Membrane ◽  
Sperm Penetration

The ultrastructural details of fertilization in the fern Marsilea vestita, including gamete approach and fusion, the fate of the spermatozoid organelles and the development of a possible block to polyspermy are described. The spermatozoid approaches the egg through layers of mucilage that surround the megaspores. It moves down the neck of the archegonium into the cavity above the egg. In order to reach the egg, it must move through a small hole in the thick wall that lies across the top of the egg. The fusion of the plasma membranes of the gametes results in an outflow of egg cytoplasm into the clear space under the sperm plasma membrane, creating a fertilization cone. All the organelles of the fertilizing spermatozoid, including nucleus, mitochondrion, microtubule ribbon, multilayered structure, and flagellar band, with approximately 150 flagella, enter the egg cytoplasm. The nucleus enters as a condensed rod of chromatin with no nuclear envelope. The chromatin begins to disperse immediately and a new nuclear envelope is formed around the chromatin by egg endoplasmic reticulum. The mitochondrion and the microtubules of the ribbon and flagella are broken down, but the fates of the flagellar band and the multilayered structure have not been determined. After spermatozoid penetration, a new extracellular layer appears above the surface of the egg, beginning in the region of sperm penetration and spreading across the top of the egg. This layer may be important in preventing other spermatozoids from fusing with the egg.

scholarly journals Diffusion and regionalization in membranes of maturing ram spermatozoa.

1984 ◽  
Vol 98 (5) ◽  
pp. 1678-1684 ◽  
Author(s):  
D E Wolf ◽  
J K Voglmayr
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Essential Feature ◽  
Lateral Diffusion ◽  
Mammalian Sperm ◽  
Epididymal Maturation ◽  
Cell Plasma ◽  
Sperm Plasma Membrane ◽  
Membrane Components

An essential feature of the "fluid mosaic model" (Singer, S. J., and G. L. Nicolson , 1972, Science (Wash. DC)., 175:720-731) of the cell plasma membrane is the ability of membrane lipids and proteins to diffuse laterally in the plane of the membrane. Mammalian sperm are capable of overcoming free random diffusion and restricting specific membrane components, both lipid and protein, to defined regions of the sperm's surface. The patterns of these regionalizations evolve with the processes of sperm differentiation: spermatogenesis, epididymal maturation, and capacitation. We have used the technique of fluorescence recovery after photobleaching to measure the diffusion of the lipid analogue 1,1'- dihexadecyl 3,3,3',3'- tetramethylindocarbocyanine perchlorate ( C16dil ) on the different morphological regions of testicular and ejaculated ram spermatozoa. We have found: (a) that the major morphologically distinct regions (head, midpiece, and tail) of the plasma membrane of both testicular and ejaculated spermatozoa are also physically distinct as measured by C16dil diffusibility; (b) that despite regional differences in diffusibility there is exchange of this lipid analogue by lateral diffusion between the major morphological regions of the plasma membrane; and (c) that epididymal maturation results in changes in C16dil diffusibility in the different regions of the sperm plasma membrane. In particular, the plasma membranes of the anterior and posterior heads become physically distinct.

Effect of sperm immobilisation and demembranation on the oocyte activation rate in the mouse

Zygote ◽  
1999 ◽  
Vol 7 (3) ◽  
pp. 187-193 ◽  
Author(s):  
T. Kasai ◽  
K. Hoshi ◽  
R. Yanagimachi
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Human Sperm ◽  
Sperm Head ◽  
The State ◽  
Human Spermatozoa ◽  
Oocyte Activation ◽  
Activation Rate ◽  
Sperm Plasma Membrane ◽  
Triton X

To analyse the effect of the state of the sperm plasma membrane on oocyte activation rate following intracytoplasmic sperm injection (ICSI), three types of human and mouse spermatozoa (intact, immobilised and Triton X-100 treated) were individually injected into mouse oocytes. At 30, 60 and 120 min after injection, maternal chromosomes and sperm nuclei within oocytes were examined. Following human sperm injection, the fastest and the most efficient oocyte activation and sperm head decondensation occurred when the spermatozoa were treated with Triton X-100. Intact spermatozoa were the least effective in activating oocytes. Thus, the rate of mouse oocyte activation following human sperm injection is greatly influenced by the state of the sperm plasma membrane during injection. When mouse spermatozoa were injected into mouse oocytes, the rates of oocyte activation and sperm head decondensation within activated oocytes were the same irrespective of the type of sperm treatment prior to injection. We witnessed that live human spermatozoa injected into moue oocytes often kept moving very actively within the ooplasm for more than 60 min, whereas motile mouse spermatozoa usually became immotile within 20 min after injection into the ooplasm. In 0.002% Triton X-100 solution, mouse spermatozoa are immobilised faster than human spermatozoa. These facts seem to suggest that human sperm plasma membranes are physically and biochemically more stable than those of mouse spermatozoa. Perhaps the physical and chemical properties of the sperm plasma membrane vary from species to species. For those species whose spermatozoa have ‘stable’ plasma membranes, prior removal or ‘damage’ of sperm plasma membranes would increase the success rate of ICSI.

Sperm–egg adhesion and fusion in mammals

2009 ◽  
Vol 11 ◽  
Author(s):  
Peter Sutovsky
Keyword(s):  
Plasma Membrane ◽  
Cell Biology ◽  
Cell Signalling ◽  
Male And Female ◽  
Membrane Biology ◽  
Animal Biotechnology ◽  
Cytoskeletal Dynamics ◽  
Sperm Plasma Membrane ◽  
Sperm Penetration ◽  
Male Patients

Fertilisation is an orchestrated, stepwise process during which the participating male and female gametes undergo irreversible changes, losing some of their structural components while contributing others to the resultant zygote. Following sperm penetration through the egg coat, the sperm plasma membrane fuses with its oocyte counterpart, the oolemma. At least two plasma membrane proteins essential for sperm–oolemma fusion – IZUMO and CD9 on the male and female gametes, respectively – have been identified recently by classical cell biology approaches and confirmed by gene deletion. Oolemma-associated tetraspanin CD81, closely related to CD9, also appears to have an essential role in fusion. Additional proteins that may have nonessential yet still facilitating roles in sperm–oolemma adhesion and fusion include oolemma-anchored integrins and oocyte-expressed retroviral envelope proteins, sperm disintegrins, and sperm-borne proteins of epididymal origin such as CRISP1 and CRISP2. This review discusses these components of the gamete fusion mechanism within the framework of gamete structure, membrane biology, cell signalling and cytoskeletal dynamics, and revisits the topic of antipolyspermy defence at the oolemma level. Harnessing the mechanisms of sperm–egg fusion is of importance to animal biotechnology and to human assisted fertilisation, wherein male patients with reduced sperm fusibility have been identified.

Ultrastructure, osmotic tolerance, glycerol toxicity and cryopreservation of caput and cauda epididymidal kangaroo spermatozoa

2006 ◽  
Vol 18 (4) ◽  
pp. 469 ◽  
Author(s):  
Rhett McClean ◽  
Catriona MacCallum ◽  
David Blyde ◽  
William V. Holt ◽  
Stephen D. Johnston
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Membrane Damage ◽  
Citrate Buffer ◽  
Plasma Membrane Damage ◽  
Osmotic Tolerance ◽  
Epididymal Maturation ◽  
Sperm Plasma Membrane ◽  
Cauda Epididymidis ◽  
Phosphate Buffered Saline

The aim of the present study was to compare cryopreservation, osmotic tolerance and glycerol toxicity between mature and immature epididymal kangaroo spermatozoa to investigate whether the lack of cryopreservation success of cauda epididymidal spermatozoa may be related to the increased complexity of the sperm ultrastructure acquired during epididymal transit. Caput and cauda epididymidal spermatozoa were recovered from red-necked wallabies (RNW; Macropus rufogriseus) and eastern grey kangaroos (EGK; M. giganteus). In Experiment 1, caput and cauda epididymidal spermatozoa were frozen and thawed using a standard cryopreservation procedure in Tris-citrate buffer with or without 20% glycerol. Although cryopreservation of caput epididymidal spermatozoa resulted in a significant increase in sperm plasma membrane damage, they were more tolerant of the procedure than spermatozoa recovered from the cauda epididymidis (P < 0.05). In Experiment 2, caput and cauda epididymidal EGK spermatozoa were diluted into phosphate-buffered saline media of varying osmolarity and their osmotic tolerance determined. Plasma membranes of caput epididymidal spermatozoa were more tolerant of hypo-osmotic media than were cauda epididymidal spermatozoa (P < 0.05). In Experiment 3, caput and cauda epididymidal RNW spermatozoa were incubated in Tris-citrate buffer with and without 20% glycerol at 35 and 4°C to examine the cytotoxic effects of glycerol. At both temperatures, caput epididymidal spermatozoa showed less plasma membrane damage compared with cauda epididymidal spermatozoa when exposed to 20% glycerol (P < 0.05). These experiments clearly indicate that epididymal maturation of kangaroo spermatozoa results in a decreased ability to withstand the physiological stresses associated with cryopreservation.

scholarly journals Novel alpha-D-mannosidase of rat sperm plasma membranes: characterization and potential role in sperm-egg interactions.

1989 ◽  
Vol 109 (3) ◽  
pp. 1257-1267 ◽  
Author(s):  
D R Tulsiani ◽  
M D Skudlarek ◽  
M C Orgebin-Crist
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Divalent Cations ◽  
Physiological Role ◽  
Soluble Form ◽  
Ph Optimum ◽  
Sperm Surface ◽  
Complete Inactivation ◽  
Sperm Plasma Membrane ◽  
Nonionic Detergent

During the course of a study of glycoprotein processing mannosidases in the rat epididymis, we have made an intriguing discovery regarding the presence of a novel alpha-D-mannosidase on the rat sperm plasma membranes. Unlike the sperm acrosomal "acid" mannosidase which has a pH optimum of 4.4, the newly discovered alpha-D-mannosidase has a pH optimum of 6.2, and 6.5 when assayed in sperm plasma membranes and intact spermatozoa, respectively. In addition, the two enzymes show different substrate specificity. The acrosomal alpha-D-mannosidase is active mainly towards synthetic substrate, p-nitrophenyl alpha-D-mannopyranoside, whereas the sperm plasma membrane alpha-D-mannosidase shows activity mainly towards mannose-containing oligosaccharides. Evidence is presented which suggest that the sperm plasma membrane alpha-D-mannosidase is different from several processing mannosidases previously characterized from the rat liver. The newly discovered alpha-D-mannosidase appears to be an intrinsic plasma membrane component, since washing of the purified membranes with buffered 0.4 M NaCl did not release the enzyme in soluble form. The enzyme requires nonionic detergent (Triton X-100) for complete solubilization. The enzyme is activated by Co2+ and Mn2+. However, Cu2+ and Zn2+ are potent inhibitors of the sperm plasma membrane alpha-D-mannosidase. At a concentration of 0.1 mM, these divalent cations caused nearly complete inactivation of the sperm enzyme. In addition methyl-alpha-D-mannoside, methyl-alpha-D-glucoside, mannose, 2-deoxy-D-glucose, and D-mannosamine are inhibitors of the sperm surface alpha-D-mannosidase. The physiological role of the newly discovered enzyme is not yet known. Several published reports in three species, including the rat, suggest that the sperm surface alpha-D-mannosidase may have a role in binding to mannose-containing saccharides presumably present on the zona pellucida.

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