bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in guinea pig sperm intracellular sodium and potassium content during capacitation and treatment with monovalent ionophores
Authors: Hyne R. V. , Edwards Kim P. , Lopata A. , Smith J. D. 
Published: February 2005

AbstractGuinea pig spermatozoa were collected from the caudae epididymides in various isotonic solutions and the intracellular sodium and potassium content was determined by atomic absorption spectroscopy. The sperm intracellular Na and K content was found to be influenced by large variations in the extracellular concentrations of these ions. Treatment of spermatozoa suspended in a saline‐based solution with the monovalent ionophores monensin or nigericin caused an approximate 2‐fold increase in the intracellular Na content and a 3–6 fold decrease in the intracellular K content. Incubation of the spermatozoa in a K+‐free minimal culture medium (MCM‐PL) at a pH of 7.6 or 8.3 for 2 hr caused an approximate 2‐fold increase in the sperm intracellular Na content and a 5‐fold decrease in the intracellular K content. The motile spermatozoa incubated for 2 hr at pH 7.6 showed less than 5% acrosome reactions, compared with 30–40% acrosome reactions after incubation at pH 8.3, in response to the addition of 5 mM Ca2+. Changes in the sperm intracellular elemental composition during culture in vitro, which may lead to an acrosome reaction, are discussed.
Scanning electron microscope study of human cervical mucus
Authors: Barros C. , Argüello B. , Jedlicki A. , Vigil P. , Herrera E. 
Published: February 2005

AbstractThe ultrastructure of human cervical mucus was studied by scanning electron microscopy. In fertile women, naturally occurring midcycle cervical mucus showed an arrangement of parallel fibers oriented along the main axis of the mucus sample. Sperm migration through a column of cervical mucus in vitro was also studied. It was found that sperm present among the longitudinal fibers were oriented parallel to the them and to the main axis of the mucus sample.
–SH and S–S involvement in Chlamydomonas mating
Authors: Forest Charlene L. 
Published: February 2005

AbstractReagents that block or cross‐link sulfhydryl (–SH) groups and those that reduce disulfide (S–S) bonds have been tested for their effects on mating in Chlamydomonas reinhardii. Wild‐type (wt) gametes of mating type + (mt+) and mt−, and a fusion‐defective mt− mutant, gam‐11, were studied. Differential sensitivities of mt+ vs mt− and of wt mt− vs gam‐11 mt− were analyzed. Concentrations of reagents that did not disrupt flagellar agglutination, the first stage of the mating reaction, were generally used. Pretreatment of mt+ gametes with the membrane permeable –SH reducing agent dithiothreitol (DTT) inhibits flagellar sexual signaling at concentrations that do not inhibit any part of the mating reaction of mt− gametes. Wt mt− is more sensitive than wt mt+ to inhibition by low concentrations of p‐chloromercuribenzoate sulfonate (pCMBS), an organic mercurial. The membrane‐impermeable reducing agent, reduced glutathione (GSH), also preferentially inhibits wt mt−. Gam‐11 mt−, a fusion‐defective mutant, which has been used to study the sensitivity of the adhesion of the plasma membrane‐associated mating structures, is less sensitive to GSH and pCMBS inhibition that is wt mt−. DDT and pCMBS cause an increase in mating structure adhesion in pretreated gam‐11. The differential inhibition of pair and group formation during gam‐11 × wt mt+ matings has suggested a possible mechanism for mating structure adhesion.
Aneuploidy in male germ cells induced by alcohol ingestion
Authors: Alvarez Marvin R. 
Published: February 2005

AbstractThe effects of ethyl alcohol ingestion, at levels comparable to human drinking, have been evaluated by cytogenetic analysis of mouse spermatogonia and primary spermatocytes. The alcohol was administered intragastrically at different doses and for various periods of time.An increase in mitotic and first division meiotic aneuploidy was observed in direct proportion to the alcohol dose. Approximately a three‐fold increase in mitotic and meiotic aneuploidy over control levels was observed in animals exposed to a daily 3 gm/kg bw dose for 6 to 28 days. The level of aneuploidy was found to return to control levels by 14 days after cessation of alcohol ingestion.Analysis of the kinetics of decrease in aneuploidy following cessation of alcohol suggests that the primal event resulting in altered chromosome numbers occurs at a stage of the cell cycle other than anaphase and therefore is not due to nondisjunction nor to anaphase lagging.
Cholinergic modulation of progesterone‐induced maturation of Xenopus oocytes in vitro
Authors: Dascal Nathan , Yekuel Rivkah , Oron Yoram 
Published: February 2005

AbstractMixed and muscarinic cholinergic agonists (acetylcholine, carbamylcholine, methacholine, oxotremorine, and pilocarpine) accelerated in a dose‐dependent manner the progesterone‐induced maturation of Xenopus laevis oocytes. None of these agonists induced oocyte maturation in the absence of progesterone. The accelerating effect of cholinergic agonists was blocked in a dose‐dependent manner by specific muscarinic antagonists (atropine and scopolamine) but not by specific nicotinic antagonists (d‐tubocurarine and hexamethonium). The specific nicotinic agonist, dimethylphenylpiperazine, alone induced maturation in the absence of progesterone. The optimal promoting effect of acetylcholine was observed when oocytes were exposed to acetylcholine for 30 min, 5 min after the addition of progesterone, and was markedly better than when oocytes were exposed to acetylcholine throughout their incubation with progesterone. The effect of acetylcholine was observed in both follicle‐enclosed and in defolliculated oocytes, indicating that follicular cells were not the target of the cholinergic drugs.
Maturation of the human oocyte in vitro: Nuclear events during meiosis (an ultrastructural study)
Authors: Sathananthan A. Henry 
Published: February 2005

AbstractStates of meiotic maturation have been traced in human oocytes cultured in vitro from prophase I to telophase II, using electron microscopy.Two hundred ten oocytes, aspirated at laparoscopy after appropriate hormonal stimulation, were cultured for 1–72 h and examined. Most oocytes were inseminated and the final phases of maturation were studied in fertilized ova.The majority of oocytes had resumed meiosis and had matured to metaphase II. Some were arrested at metaphase I, and a few remained inactive at the germinal vesicle stage. Maturation of oocytes to metaphase II was achieved 3 h after laparoscopy; to telophase II, 3 h after insemination. Maturation of some oocytes to metaphase II may have occurred in the ovary.Immature oocytes had eccentric nuclei containing dense fibrillar nucleoli. Corona cell processes formed complex junctions with the oolemma and a type of interaction analogous to neural transmission was observed. Maturing oocytes showed typical barrel‐shaped spindles, but no centrioles or asters. Chromosomes were attached to microtubules via kinetochores. Midbodies were elaborated in the ooplasm and determined the plane of cleavage of polar bodies. Some aspects of oocyte degeneration, aberrations of oocyte maturation, and consequences of aging are also reported.The significance of cytoplasmic maturation that occurs concurrently with nuclear maturation is discussed in relation to assessment of oocytes for in vitro fertilization.
The action of gossypol on rat germinal cells
Authors: Baccetti Baccio , Bigliardi Elisa , Burrini Anna G. , Renieri Tommaso , Selmi Gloria 
Published: February 2005

AbstractAdult male Sprague‐Dawley rats were fed daily with 25 mg/kg of gossypol acetic acid for 55 days. The examination of the testis revealed the constant integrity of the blood‐testis barrier. The earliest damage to the germinal cells appeared on the 14th day of treatment in spermatids in stage 18‐19, and consisted of mitochondrial swelling and cristae disorganization, which was manifested in an altered assembly of the mitochondrial helix and possible axonemal alterations. It appeared that the target cell was a 30–37‐day‐old spermatid that showed the first alterations 6–14 days later, when it reached stage 18. The mitochondrial and eventual axonemal damage was conserved after the migration into the epididymis, affecting 6% of the total sperm population on the 14th day of treatment and reaching the maximum (100%) on the 25th day of treatment. On the 5th day of treatment, epididymal spermatozoa revealed, moreover, the presence of other tail alterations: lack of half of the axonemal components (also in sperm with unaffected mitochondria), loss of midpiece plasma membrane, and breaking of the outer accessory fibers. The conclusion is that a direct action of gossypol on epididymal spermatozoa is superimposed on the action earlier exerted on the spermatids.
A new embryonic antigen, p67, present during mouse preimplantation development
Authors: Banka Carole L. , Calarco‐Gillam Patricia D. 
Published: February 2005

AbstractAn antibody prepared against nullipotential teratocarcinoma stem cells (A‐N1) detects cell surface antigens expressed by early mouse embryos and inhibits in vitro development of embryos in the absence of complement [Calarco and Banka, 1979]. Here we report the immunoprecipitation and electrophoretic characterization of A‐N1‐detected antigens from preimplantation mouse embryos. Predominant antibody activity is directed against a 67,000‐dalton glycoprotein (p67) with a mean pI of 5.3, which has not been previously described. This protein is not detected, at least as p67, after culture of embryos in tunicamycin. The p67 antigen is also expressed by pluripotential PSA1 teratocarcinoma cells but not by several different differentiated mouse cell types.
A comparison of fertility in vitro and in vivo after exposure of male mice to high environmental pressure
Authors: Fraser Lynn R. , Monk Susan , Wardley‐Smith Bridget , Cohen Shara , Halsey Michael J. 
Published: February 2005

AbstractMale mice of the TO strain were exposed to 50 ATA helium (0.5 ATA oxygen) over 5 weeks and then assessed for fertility both in vitro and in vivo. Significantly lower values for acrosome loss and fertilization of zona intact eggs in vitro were obtained with spermatozoa from the pressure‐treated males. These results, coupled with the significant decrease in incidence and degree of polyspermy in zona‐free eggs, indicated that fewer competent cells were present after preincubation under capacitating conditions. Fewer motile cells were observed in most samples, along with a reduction in the incidence of hyperactivated motility in some. Testis weight was also significantly lower. Results of fertilization in vivo, after mating with untreated females, showed a consistent trend toward subfertility, with a lower pregnancy rate and a smaller litter size. These differences did not reach significance, however, unlike those obtained in earlier in vivo experiments with males of the BALB/c strain. The discrepancy between in vitro and in vivo results with TO males probably represents differences between unselected and selected sperm populations, while that observed in vivo between the two strains probably reflects the superior reproductive capacity of the TO strain.
Adenosine and gpp(NH)p modulate mouse sperm adenylate cyclase
Authors: Stein D. M. , Fraser L. R. , Monks N. J. 
Published: February 2005

AbstractThe possible roles of adenosine and the GTP analogue Gpp(NH)p in regulating mouse sperm adenylate cyclase activity were investigated during incubation in vitro under conditions in which after 30 min the spermatozoa are essentially uncapacitated and poorly fertile, whereas after 120 min they are capacitated and highly fertile. Adenylate cyclase activity, assayed in the presence of 1 mM ATP and 2 mM Mn2+, was determined by monitoring cAMP production. When adenosine deaminase (1 U/ml) was included in the assay to deplete endogenous adenosine, enzyme activity was decreased in the 30‐min suspensions but increased in the 120‐min samples (P < 0.02). This suggests that endogenous adenosine has a stimulatory effect on adenylate cyclase in uncapacitated spermatozoa but is inhibitory in capacitated cells. Since the expression of adenosine effects at low nucleoside concentrations usually requires guanine nucleotides, the effect of adding adenosine in the presence of 5 x 10–5 M Gpp(NH)p was examined. While either endogenous adenosine or adenosine deaminase may have masked low concentration (10−9−10−7 M) effects of exogenous adenosine, a marked inhibition (P < 0.001) of adenylate cyclase activity in both uncapacitated and capacitated suspensions was observed with higher concentrations (>10−5 M) of adenosine. Similar inhibition was also observed in the absence of Gpp(NH)p, suggesting the presence of an inhibitory P site on the enzyme. In further experiments, the effects of Gpp(NH)p in the presence and absence of adenosine deaminase were examined. Activity in 30‐min suspensions was stimulated by the guanine nucleotide and in the presence of adenosine deaminase this stimulation was marked, reversing the inhibition seen with adenosine deaminase alone. In capacitated suspensions the opposite profile was observed, with Gpp(NH)p plus adenosine deaminase being inhibitory; again, this was a reversal of the effects obtained in the presence of adenosine deaminase alone, which had stimulated enzyme activity. These results suggest the existence of a stimulatory adenosine receptor site (Ra) on mouse sperm adenylate cyclase that is expressed in uncapacitated spermatozoa and an inhibitory receptor site (Ri) that is expressed in capacitated cells, with guanine nucleotides modifying the final response to adenosine. It is concluded that adenosine and guanine nucleotides may regulate mouse sperm adenylate cyclase activity during capacitation.
Nuclear morphogenesis during spermiogenesis in the nudibranch molluscHypselodoris tricolor (Gastropoda, opisthobranchia)
Authors: Medina A. , Moreno J. , López‐Campos J. Ló 
Published: February 2005

AbstractAn electron microscope study was carried out on Hypselodoris tricolor spermatids to describe the development of the nuclear morphogenesis and investigate the possible cause(s) of the change in the shape of the spermatid nucleus during spermiogenesis. Three different stages may be distinguished in the course of the nuclear morphogenesis on the basis of the morphology and inner organization of the nucleus. Stage 1 spermatid nuclei are spherical or ovoid in shape and the nucleoplasm finely granular in appearance. Stage 2 nuclei exhibit a disc‐ or cup‐shaped morphology, and the chromatin forms short, thin filaments. During stage 3, a progressive nuclear elongation takes place, accompanied by chromatin rearrangement, first into fibers and then into lamellae, both formations helically oriented. A row of microtubules attached to the nuclear envelope completely surrounds the nucleus. Interestingly, the microtubules always lie parallel to the chromatin fibers adjacent to them. Late stage 3 spermatids show the highest degree of chromatin condensation and lack the manchette at the end of spermiogenesis. Our findings indicate the existence of a clear influence exerted on the chromatin by the manchette microtubules, which appear to be involved in determining the specific pattern of chromatin condensation in Hypselodoris tricolor.
19‐Norandrostenedione (4‐estrene‐3,17‐dione) Inhibits Porcine Oocyte Maturation In Vitro
Authors: Daniel S. A. J. , Khalil M. W. , Armstrong D. T. 
Published: February 2005

AbstractRecent work has shown that 19‐norandrostenedione is a major steroidal component of porcine follicular fluid; however, little is known about its role(s) in the regulation of follicular function. This study was designed to examine the effect of 19‐norandrostenedione on porcine oocyte maturation in vitro. Oocyte‐cumulus complexes were isolated from medium (3–6‐mm diameter)‐sized prepubertal pig follicles and incubated for 12 h in medium with or without dibutyryl cyclic AMP ((Bu)2cAMP, 1 mM) with or without testosterone (5 x 10−7 M) or 19‐norandrostenedione (5 x 10−7 M). In medium alone, 70.8% of oocytes spontaneously resumed meiosis as evidenced by the occurrence of germinal vesicle breakdown. Oocyte maturation was inhibited by (Bu)2cAMP (44.6% of oocytes matured). Although neither steroid alone affected maturation, both testosterone and 19‐norandrostenedione enhanced the effect of (Bu)2cAMP (22.5 and 19.6%, respectively, resumed meiosis).The effects of testosterone and 19‐norandrostenedione on (Bu)2cAMP‐inhibited oocyte maturation were dose dependent and there was no significant difference between the actions of the steroids. The effect of 19‐norandrostenedione was reversible and dependent on the presence of an intact cumulus. Hydroxyflutamide (SCH‐16423), a nonsteroidal compound known to block androgen receptors, abolished the effects of both testosterone and 19‐norandrostenedione on germinal vesicle breakdown, indicating that the actions of these steroids are truly androgenic.The results of this study suggest that 19‐norandrostenedione may be of physiological importance in the regulation of porcine oocyte maturation.
Immunochemical identification of multiple cell surface antigens appearing during specific stages of mouse spermatogenesis
Authors: O'Brien Deborah A. , Millette Clarke F. 
Published: February 2005

AbstractCell surface antigens that appear in a defined temporal sequence during mouse spermatogenesis were previously detected serologically, but not identified biochemically, with four heterologous antibodies prepared against purified populations of pachytene spermatocytes (AP), round spermatids (ARS), vas deferens spermatozoa (AVDS), and mixed seminiferous cells (ASC) [Millette and Bellvé, J Cell Biol 74:86–97, 1977]. These antigens have now been identified immunochemically on nitrocellulose blots from SDS polyacrylamide gels. Three antisera (AP, ARS, and ASC) recognize a similar subset of determinants on one‐dimensional immunoblots of germ cells and plasma membranes prepared from a mixed population of late spermatogenic cells. Comparisons of minor bands to reveal differences among these antisera. AVDS exhibits the least complex binding pattern. The results indicate that at least ten surface constituents appear during the pachytene stage of meiosis, coincident with a period of maximal RNA and protein synthesis [Monesi, Exp Cell Res 39:197–224, 1965]. Furthermore, two‐dimensional immunoblot comparisons of plasma membranes isolated from pachytene spermatocytes and round spermatids reveal differences between surface determinants detectable at these two spermatogenic stages. For example, ASC recognizes two newly described proteins that are restricted to pachytene spermatocytes (˜ Mr 57,000, pI 6.45) and to round spermatids (˜ Mr 39,500, pI 4.85), respectively.
Effects of carbon dioxide acidification of mouse oocytes before in vitro fertilization, culture, and transfer
Authors: Puissant F. , Degueldre M. , Buisson L. , Leroy F. 
Published: February 2005

AbstractThe effects of varying pH levels on superovulated mouse oocytes before in vitro fertilization, culture, and transfer were investigated. Mouse oocytes acidified for 1 hour with 20% CO2 (pH 6.9) exhibited a wide range of alterations. Five hours after insemination, 25% of these eggs showed different degrees of cytolysis and their perivitelline space contained numerous spermatozoa. At 12 hours normal‐looking eggs from this group showed a higher proportion of polypronuclear zygotes than the control group (exposed, 51%; controls, 18%). Acidification thus markedly increased the permeability of the zona pellucida and/or interfered with the normal block to polyspermy. Fewer eggs achieved the two‐cell stage among groups submitted to acidotic pH levels (6.9 to 6.6). In contrast, alkaline conditions (pH 7.8) did not reduce the proportion of two‐cell embryos. However, only eggs maintained at pH 7.5 were capable of producing 80% of blastocysts. In other groups developmental blockage occurred mainly between stages 2 and 4. A significant reduction was found in the proportion of recipient females becoming pregnant after intrauterine transfer of blastocysts originating from CO2‐treated oocytes. This difference might be related to the existence of a large polyploid population among experimental eggs.
Variables affecting the yield and developmental potential of embryos following superstimulation and in vitro fertilization in rhesus monkeys
Authors: Boatman Dorothy E. , Morgan Patricia M. , Bavister Barry D. 
Published: February 2005

AbstractThree follicular‐stimulation protocols were compared to evaluate the yield and quality of oocytes obtained from rhesus monkeys. Five animals received a high‐dose regimen of PMSG (protocol I), three received a lower‐dose regimen (protocol II), and two received Clomid‐Pergonal (protocol III). Oocytes were recovered at laparoscopy after HCG injection, fertilized in vitro, and cultured up to the blastocyst stage. Yields of mature oocytes were 17.2 ± 13.0 (80% of total recovered), 6.7 ± 6.6 (41%), and 4.5 ± 2.5 (90%) per stimulated cycle for protocols I, II, and III, respectively. Of mature oocytes, 72%, 45%, and 89% were fertilized for protocols I, II and III, respectively. Protocol I produced the most fertilized oocytes per stimulated cycle (11.6 ± 11.6) and the greatest E2 production (approximately fourfold that maximally expected for an unstimulated cycle). For the combined protocol I and II results, there was a significant correlation (P ⩽ 0.05) between mean embryo development score and E2 production. Fertilized oocytes from protocol I yielded 7.8 ± 8.0 morulae and 6.8 ± 7.2 early zonal blastocysts per cycle. After transfer of nine singleton embryos to surrogate recipients, one live birth resulted. We conclude that our high‐dose PMSG regimen offers the best means at present for obtaining susbstantial numbers of developmentally competent oocytes in rhesus monkeys and that more extensive use of rapid serum E2 assays for monitoring both stimulated cycles and those of potential surrogate recipients could help to predict the success of in vitro fertilization and embryonic development following embryo transfer in rhesus monkeys.
Interaction of boar spermatozoa with porcine oocytes: Increase in proteins with high affinity for the zona pellucida during epididymal transit
Authors: Peterson R. N. , Hunt W. P. , Henry L. H. 
Published: February 2005

AbstractCauda boar sperm but not caput sperm bind to isolated porcine oocytes, and several cauda sperm plasma membrane proteins (PMPs) with high affinity for isolated zonae have been identified. These PMPs migrate with apparent molecular weights near 70, 45 and 30 K [Peterson et al, Gamete Res 12: 91–100, 1985]. When caput plasma membranes (PM) were fractionated on dextran sulfate (DS) agarose and compared to cauda PM similarly fractionated, less protein with high affinity for DS bound to the column, and significant differences in the PMPs eluted with increasing concentration of NaCl were observed. The PMPs at ∼70, ∼45, and ∼30 K, noted above, and two bands near ∼20K were present in fractions from cauda PM but were absent or present in only small quantities in caput PM. Cauda PM fraction eluted at high salt were effective in blocking the binding of sperm to isolated oocytes; caput PM fractions were not. Antibodies to the cauda PMPs eluted at high salt, which blocks the binding of capacitated sperm to eggs and fertilization in vitro, were absorbed by cauda PMV but not by caput PMV. These findings suggest that the ability of boar sperm to attach to porcine oocytes develops as the result of the addition of one or more of these PMPs to sperm during epididymal transit.