bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in cortical granules during porcine oocyte maturation
Authors: Cran D. G. , Cheng W. T. K. 
Published: February 2005

AbstractThe structure, number, and distribution of cortical granules in porcine oocytes during maturation induced by human chorionic gonadotrophin (HCG) are reported.The number of granules remained constant for 30 hr following HCG. Thereafter, there was an approximate doubling by 50 hr. At all times examined, a dark and light form were present. Up to 40 hr the latter predominated while at 50 hr there was a marked increase in the number of the former. Movement of cortical granules to the plasma membrane took place between 20 and 30 hr post‐HCG. The changes in cortical granules are correlated with the capacity of the oocytes to undergo a block to polyspermy.
The acrosomal region of the spermatozoon of Ciona intestinalis: Its relationship with the binding to the vitelline coat of the egg
Authors: Rosati F. , Pinto M. R. , Casazza G. 
Published: February 2005

AbstractThis paper describes a study of the apical region of the spermatozoon of Ciona intestinalis before and during its binding to the vitelline coat of the egg. A combination of the techniques of thin sectioning, negative staining, and freeze fracture has revealed that in the apical‐most region, where a small acrosomal vesicle lies on the flat tip of the nucleus, there is a cap‐like region almost completely free of particles on the P face of the plasma membrane. The particle‐free area is surrounded by two circlets of orderly arranged particles. Upon binding to the vitelline coat the particles of the distal circlet show a partial displacement, while the particles of the apical circlet remain unaltered. The relationship between the apical circlet and the binding process is discussed. The final step of the acrosome reaction, which occurs in only a few of the bound spermatozoa, consists in the fusion of the plasma membrane with the acrosomal membrane, in the dehiscence of the acrosomal contents and finally in the formation of membrane tubules.
A molecular membrane model of sperm capacitation and the acrosome reaction of mammalian spermatozoa
Authors: Langlais Jean , Roberts Kenneth D. 
Published: February 2005

AbstractThe abundance of data pertaining to the metabolism of lipids in relation to mammalian fertilization has warranted an effort to assemble a molecular membrane model for the comprehensive visualization of the biochemical events involved in sperm capacitation and the acrosome reaction. Derived both from earlier models as well as from current concepts, our membrane model depicts a lipid bilayer assembly of space‐filling molecular models of sterols and phospholipids in dynamic equilibrium with peripheral and integral membrane proteins. A novel feature is the possibility of visualizing individual lipid molecules such as phosphatidylcholine, phosphatidylethanolamine, lysophospholipids, fatty acids, and free or esterified cholesterol. The model illustrates enzymatic reactions which are believed to regulate the permeability and integrity of the plasma membrane overlying the acrosome during interactions between the male gamete and capacitation factors present in fluids of the female genital tract. The use of radioactive lipids as molecular probes for monitoring the metabolism of cholesterol and phosphatidylcholine revealed the presence of (1) steroid sulfatase in hamster cumulus cells, (2) lecithin: cholesterol acyltransferase in human follicular fluid, (3) phospholipase A2, and (4) lysophospholipase in human spermatozoa. These enzymatic reactions can be integrated into a pathway that provides a link between the concepts of lysophospholipid accumulation in the sperm membranes and alteration of the cholesterol/phospholipid ratio as factors involved in the preparation of the membranes for the acrosome reaction. Capacitation is viewed as a reversible phenomenon which, upon completion, results in a decrease in negative surface charge, an efflux of membrane cholesterol, and an influx of calcium between the plasma and outer acrosomal membranes. Triggered by the entry of calcium, the acrosome reaction involves phospholipase A2 activation followed by a transient accumulation of unsaturated fatty acids and lysophospholipids implicated in membrane fusion which occurs during the formation of membrane vesicles in spermatozoa undergoing the acrosome reaction.
Developmental capability of rat oocytes matured in vitro in defined medium
Authors: Fleming Alan D. , Evans Gareth , Walton Elizabeth A. , Armstrong David T. 
Published: February 2005

AbstractThe normality of in vitro matured oocytes was compared to that of in vivo matured (ovulated) oocytes at the following stages of development: germinal‐vesicle breakdown, first polar body formation, fertilization (two polar bodies and two pronuclei with a sperm tail or first cleavage), and fetal development (day 20 fetuses). At all points, the in vitro oocytes exhibited a reduced ability, with oocytes matured cumulus‐free having the poorest. The exposure of oocytes to human chorionic gonadotropin (hCG) for 2 hr before collection or during incubation improved their rates of maturation and development to day 20 fetuses but not their ability to undergo fertilization. While beneficial, the exposure to gonadotropins before or during maturation was not essential, as evidenced by the production of two day 20 fetuses matured and fertilized in vitro without any gonadotropin (luteinizing hormone or hCG) treatment in vivo or in vitro. These data demonstrate that in the population of in vitro matured oocytes there exist individuals wholly competent of complete normal development, albeit in a reduced proportion in comparison to normally matured and ovulated oocytes. That the in vitro handling, treatment, and culture of the oocytes may be responsible for some of the reduced developmental ability observed is suggested by the developmental abilities of ovulated oocytes under different conditions. Ovulated oocytes fertilized in the donor had the highest rates of development (46%), followed by those fertilized after transfer into mated recipients' oviducts (20%). The lowest rate was achieved with in vitro fertilized oocytes (7%), which represented the group subject to the greatest degree of manipulation and distinction from the normal in vivo process.
Biochemical changes in cervical mucus‐factor infertility
Authors: Lutjen P. J. , Handley C. J. , de Witt M. T. , Trounson A. O. , McBain J. C. 
Published: February 2005

AbstractCervical‐factor infertility has generally been attributed to the presence of antispermatozoal antibodies in the secretions of the uterine cervix, despite the fact that the incidence of sperm‐specific antibodies in these women is generally low. We report here a modification in the structure of the cervical mucus of patients with a diagnosed cervical factor. Cervical mucus from patients with a cervical factor of nonimmunological origin, collected during the periovulatory phase of the menstrual cycle, had (1) a significant decrease in the content of glycosidically bound sialic acid and (2) an increased ability to act as an acceptor for sialic acid from cytidine‐5′‐monophospho‐N‐acetylneuraminic acid (CMP‐sialic acid) when incubated with an exogenous sialyltransferase; in comparison to mucus from normal fertile women. Both siaiyltransferase and fucosyltransferase activities were detected in cervical mucus, but there was no difference between fertile normal and cervical‐factor patients using the assays described. These results reinforce a possible role for sialic acid residues and their associated glycosyltransferases in the regulation of spermatozoal–cervical mucus interaction.
Lectin‐induced blockage of developmental processes in preimplantation mouse embryos in vitro
Authors: Zuzack John S. , Tasca Richard J. 
Published: February 2005

AbstractThis study attempts to assess the developmental importance of cell surface glycoconjugates of preimplantation mouse embryos. This was done by incubating early embryos in various lectins and analyzing subsequent development. If specific cell surface glycoconjugates (lectin receptors) are linked to specific developmental processes, such as cell division, compaction, and blastocyst formation, then different lectins should block these different developmental processes. The results show that wheat‐germ agglutinin (WGA; N‐acetyl‐D‐glucosamine‐specific) at 50 μg/ml prevents the cell division of four‐cell embryos. However, this effect of WGA occurs only in embryos with intact zonae pellucidae. Concanavalin A (Con A; α‐D‐glucose and α‐D‐mannose‐specific) treatment, 20 μg/ml, of four‐cell or early eight‐cell embryos prevents compaction, the first major change in cell shape in early mouse embryogenesis. Divalent succinly Con A does not affect development, suggesting that the Con A effect is due to crosslinking of cell surface glycoconjugates. Exposure of four‐cell or early eight‐cell embryos to 10 μg/ml Lotus Tetragonolobus puprureas agglutinin (LTA; α‐L‐fucose‐specific) or 25 μg/ml Limulus polyphemus agglutinin (LPA; sialic acid‐specific) allows compaction or development to the morula stage, but blocks blastocyst formation. All lectins tested retard cell division to some extent. Late morulae and early blastocysts are more resistant than earlier stages to all of the lectins studied. This study demonstrates that very low concentrations of these lectins affect different developmental processes, presumably based upon their sugar specificities.
A qualitative comparison of protein synthesis in the preimplantation embryos of four rodent species (mouse, rat, hamster, gerbil)
Authors: Norris Michael L. , Barton Sheila C. , Surani M. Azim H. 
Published: February 2005

AbstractAn examination of the protein profiles obtained from preimplantation embryos of mouse, rat, hamster, and gerbil revealed marked species differences in the one‐cell fertilized eggs but a striking similarity in the major proteins produced by blastocysts. The early change in protein profile observed in all four species suggests that activation of the embryonic genome before the second cleavage division is a rodent characteristic. The initial marked species differences resulting from putative maternal transcripts could be important in the establishment and maintenance of species integrity.
Interactions of seminal plasma and glycosaminoglycans on acrosome reactions in bovine spermatozoa in vitro
Authors: Lee Chin N. , Handrow Richard R. , Lenz Richard W. , Ax Roy L. 
Published: February 2005

AbstractPrevious reports indicate that glycosaminoglycans (GAGs) would enhance the occurrence of acrosome reactions in sperm in vitro, but continuous exposure of those sperm to seminal plasma prevented a significant incidence of acrosome reactions. This study was designed to evaluate the interaction of GAGs and seminal plasma to promote acrosome reactions in bull sperm in vitro. Epididymal sperm required 22 hr to exhibit acrosome reactions in response to GAGs whereas only 9 hr were needed to achieve the same effect with washed ejaculated sperm. Exposure of epididymal sperm to seminal plasma for 20 min shortened the time for induction of the acrosome reaction to 9 hr. Scatchard analyses of displacement data suggested an alteration in the binding affinity of 3H‐heparin to epididymal sperm membrane following the short‐term exposure to seminal plasma. High doses (250 and 500 μg/ml) of heparin, heparan sulfate, and chondroitin‐4‐sulfate were without effect, but doses <100 μg/ml were stimulatory in terms of enhancing acrosome reactions. Compositional studies with seminal plasma revealed a total GAG content of 1.6 mg/ml, proportioned as 61.6% chondroitin sulfates, 17.6% heparin‐like material, 0.3% hyaluronic acid, and 20.5% undetermined GAG. It is proposed that seminal plasma can alter the ability of sperm to respond to GAGs, and the high concentrations of GAGs endogenous to seminal plasma may prevent premature initiation of the membrane perturbations necessary for the acrosome reaction.
Alteration of sperm thiol‐disulfide status and capacitation in the guinea pig
Authors: Fleming Alan D. , Kosower Nechama S. , Yanagimachi Ryuzo 
Published: February 2005

AbstractEpididymal spermatozoa of the guinea pig were incubated under conditions known to promote a rapid synchronous capacitation in a large proportion of the spermatozoa (Ca2+‐free medium with lysophosphatidylcholine, LC) or in Ca 2+‐free medium without LC. To study the effects of altered thiol‐disulfide status and content, incubations were conducted with reagents that maintain and increase thiol groups (DTT, GSH), maintain and increase disulfide groups (diamide, GSSG), or which irreversibly block thiol groups by alkylation (NEM). The permeable DTT inhibited LC‐induced capacitation and at high concentrations diminished the percentage of acrosome reactions in capacitated spermatozoa. The permeable diamide exhibited a stimulatory effect upon capacitation. The largely impermeable GSH and GSSG exhibited effects similar to their respective permeable counterparts but their effects were moderate and required extremely high concentrations. The DTT inhibition of LC‐induced capacitation was reversible by washing and a further 1 hr incubation. In this final incubation after removal of DTT by washing, LC was absent too so its stimulatory effect must have been accomplished prior to washing and in the presence of DTT. NEM‐alkylation of the existing thiol population did not affect LC‐induced capacitation but alkylation of the increased thiol population after prior DTT treatment was inhibitory of capacitation. These results suggest that the maintenance and/or formation of disulfide groups on enzymes or structural proteins may be a component of the capacitation process. In contrast, the formation and maintenance by alkylation of increased thiol groups but not the maintenance of existing thiol groups, is inhibitory of capacitation. The relevance of these findings to a role for a thiol‐sensitive proteinase in capacitation is discussed.
Mouse oocyte maturation modulated by a granulosa cell factor and by heparin and heparan sulfate
Authors: Sato Eimei , Ueno Hiroshi , Koide S. S. 
Published: February 2005

AbstractOocyte maturation‐preventing factor (OMPF) was extracted from bovine granulosa cells with a buffer containing 1 M urea and 5 mM EDTA. OMPF was partially purified by gel filtration on Sephadex G25 and by reversed‐phase high performance liquid chromatography. The maturation‐preventing activity of purified fractions was determined by measuring their capacity to block the spontaneous dissolution of the germinal vesicle (GVBD) of isolated cumulus‐enclosed mouse oocytes. Hyaluronic acid, chondroitin sulfate, heparin, heparan sulfate, keratan sulfate, and dextran sulfate at concentrations of 500 μg/ml did not affect the frequency of GVBD of isolated mouse oocytes. Heparin and heparan sulfate, however, blocked the inhibitory effect of OMPF, whereas the inhibition of GVBD induced with dibutyryl cAMP, forskolin, W7 (calmodulin antagonist), and 3‐isobutyl‐l‐methylxanthine (phosphodiesterase inhibitor) was not blocked. OMPF was eluted in the adsorbed fraction when chromatographed on heparin‐Agarose, showing interaction of OMPF with heparin. The present results suggest that the glycosaminoglycan matrix may influence OMPF action on oocytes.
The cortical reaction in pig oocytes during in vivo and in vitro fertilization
Authors: Cran D. G. , Cheng W. T. K. 
Published: February 2005

AbstractThe structure of pig oocytes after in vivo and in vitro fertilization and following treatment with the ionophore A23187 with differing levels of calcium are described, with particular reference to the cortical granules.Fertilization in vivo and in vitro resulted in cortical granule exocytosis. Sperm penetration in vivo was more rapid than in vitro and resulted in the dispersal of the cortical granules' contents in the perivitelline space following exocytosis. The contents of the granules remained adjacent to the plasmalemma after in vitro fertilization and suboolemmar vesicles were less numerous than after in vivo fertilization. High calcium levels were necessary to induce the dispersal of the cortical granule contents following treatment with ionophore. The observations are discussed regarding their relevance to the blockage to polyspermy.
Cytochemical localization of membrane‐bound Mg2+‐dependent ATPase activity in guinea pig sperm head before and during the acrosome reaction
Authors: Usui Noriko , Yanagimachi Ryuzo 
Published: February 2005

AbstractThe distribution of ATPase activity in the heads of uncapacitated, capacitated, and acrosome‐reacting guinea‐pig spermatozoa was examined cytochemically using the Wachstein‐Meisel's technique. In uncapacitated spermatozoa, the reaction products of the enzyme activity were localized on both the inner surface of the plasma membrane and the outer surface of the outer acrosomal membrane. The activity was Mg2+‐dependent and inhibited by both Ca2+ and SH‐blocking agents. This Mg2+‐dependent ATPase activity was also demonstrated at the same sites in capacitated spermatozoa, whereas it was completely absent in acrosome‐reacting spermatozoa. Although we did not determine the exact time of inactivation of the enzyme, it appeared to occur before the plasma membrane fused with the underlying outer acrosomal membrane. The abrupt loss of the Mg2+‐dependent ATPase activity in the plasma and outer acrosomal membranes immediately before the onset of the acrosome reaction seems to suggest that inactivation of this enzyme by Ca2+ is one of the important biochemical events involved in the acrosome reaction.
An in vitro technique to study penetration of hamster oocyte‐cumulus complexes by using physiological numbers of sperm
Authors: Corselli J. , Talbot P. 
Published: February 2005

AbstractWe have developed an inexpensive in vitro system for studying cumulus penetration and fertilization by using physiological numbers of sperm. This system simulates conditions believed to exist in vivo more closely than any in current usage. In this system, 1–100 hamster sperm are used to challenge fresh hamster oocyte‐cumulus complexes (OCC). Only fresh (nonoviducal) OCC are used, as they present the most stringent challenge to sperm. Because sperm numbers are low, OCC do not disperse, and sperm can be studied microscopically during penetration of the cumulus oophorus and corona radiata. These conditions permit microscopic assessment of the sperm acrosome. Video tapes of experiments allow easy review and analysis of experiments. Results obtained employing this technique show that, in vitro, (1) capacitated, acrosome‐intact hamster sperm can penetrate the extracellular matrix between cumulus cells and bind to the zona pellucida; (2) the “figure‐eight motility” characteristic of hyperactivated hamster sperm swimming in culture medium is suppressed when sperm swim in the extracellular matrix between cumulus cells; and (3) fertilization occurs in capillary tubes when low numbers of sperm are used. The in vitro system that we have described will be useful in analyzing the mechanisms used by sperm to penetrate the cumulus and corona radiata and to clarify the role of the acrosomal enzymes in fertilization.
Localization of antigens on the inner‐acrosomal membrane of the rabbit sperm by immunofluorescence
Authors: Sheikhnejad Reza G. , Srivastava P. N. 
Published: February 2005

AbstractThe acrosome‐reacted spermatozoa interact with the zona pellucida through their limiting inner acrosomal membrane (IAM). The antigenic properties of IAM were determined using the antibody to IAM raised in a male guinea pig. The antisera was incubated with the acetone powder of rabbit lung, liver, kidney, heart, muscle, and blood cells. The unabsorbed antibodies specifically interacted with antigens on the IAM as determined by the immunofluorescence technique.
Cationic probes: Specificity of distribution of metal‐binding sites in bovine sperm
Authors: Nelson Leonard , Gardner Mary E. 
Published: February 2005

AbstractSalts of transition elements that alter the rate of sperm cell movement act at or near calcium‐binding sites. After living bull sperm cells had been preincubated in VO43−, Ni2+, Zn2+, Mn2+, and also La3+, they were then fixed. Crisply defined organelles and the absence of particulate deposits in the morphological controls contrasted sharply with the treated specimens; the latter contained regions of increased electron density, the nature and distribution of which depended on the test substance, reflecting the differential affinities of the specific ions. La3+ formed fine dense areas, mainly at the exocytic surface of the plasma membrane. VO43− marks the cell surface but also left particulate densities within the cell. Ni2+ caused a nearly uniformly dense deposit at the surface and on the satellite fibers and axonemal microtubules. Zn2+ formed less uniform but coarser deposits, while in Mn2+ the distribution was similar to that in Zn2+ but much denser in the axonemal matrix and on the satellite fibers. Verapamil restricted the size and number of the opacities, while procaine permitted a similar distribution of slightly larger size reaction product. The differences in size and distribution of the enhanced densities were consistent and replicable for the individual assay substances. Vanadate, which specifically inhibits Na, K‐ATPase, bound to ouabain‐sensitive enzyme loci, however, completely disrupting the axonemal complex. This suggests that an important role of dynein in flagellar motion may relate to intracellular transport of Ca2+.
Effects of extracellular cations and energy substrates on the acrosome reaction of precapacitated guinea pig spermatozoa
Authors: Murphy S. J. , Roldan E. R. S. , Yanagimachi R. 
Published: February 2005

AbstractIt is well established that extracellular Ca2+ and an alkaline pH are essential for the acrosome reaction of precapacitated guinea pig spermatozoa. In the present study, we investigated how other extracellular cations (Na+, K+, and Mg2+) and energy substrates (glucose, lactate, and pyruvate) affect the acrosome reaction of these spermatozoa. The effect of osmolality of the medium on the reaction was also examined.It was found that precapacitated spermatozoa could undergo the acrosome reaction in a medium with an osmolality of as low as 160 mOsmol or as high as 500 mOsmol. However, the osmolality range within which large proportions of spermatozoa underwent the acrosome reaction while retaining strong motility was 220 to 380 mOsmol. Extracellular Na+ was essential for the reaction to occur. A few spermatozoa could acrosome react in a medium with a very low concentration of Na+ (5 mM or less), but a higher concentration of Na+ (more than 60 mM) was needed to ensure the acrosome reaction in the majority of spermatozoa. High concentrations of extracellular K+ were not essential for the reaction, but the presence of K+ at physiological level ensures that the reaction will occur consistently at a high rate. Extracellular Mg2+ was not required for the acrosome reaction. The high concentrations of Mg2+ (up to 20 mM) and K+ (up to 60 mM) that were tested did not affect the incidence of the acrosome reaction. Exogenous substrates were not essential for the reaction. Although the majority of precapacitated spermatozoa could acrosome react in substrate‐free medium, the presence of substrates in the medium, particularly that of pyruvate, seemed to be beneficial to the reaction.
The decrease of Xenopus egg membrane capacity during activation might be due to endocytosis
Authors: Bernardini Giovanni , Ferraguti Marco , Peres Antonio 
Published: February 2005

AbstractAn endocytotic process in Xenopus eggs was studied by direct visualization of the fluorescent tracer lucifer yellow CH in 1‐μm‐thick sections. Eggs fixed 3 min after activation show small fluorescent vesicles in the cortex; those fixed after 30 min show mainly large vesicles. This process is related to membrane recycling after cortical granule exocytosis and can account for the observed decrease of the effective membrane capacity.