bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of lloprost, a stable prostacyclin analog, PGE2 and PGF2α on rabbit blastocysts
Authors: Jones Marjorie A. , Harper Michael J. K. 
Published: February 2005

AbstractThe uptake of prostaglandins (PGs) into day‐6 rabbit blastocysts was studied. Uptake of PGE2 and PGF2α was temperature sensitive and nonsaturable up to 1,000 nM external concentration. In contrast, uptake of Iloprost, a stable prostacyclin analog, was unaffected by temperature, and showed apparent saturation at >2 nM concentration. Individual blastocysts exposed to 0.2 μM radioinert prostaglandins for 1 hr did not swell significantly. Blastocyst concentration of PGF2α was 4.8 ± 2.1‐fold higher than that of PGE2, which was 9.5 ± 2.4‐fold greater than that of 6‐keto‐PGF1α (the stable metabolite of prostacyclin). Uptake of tritiated water was increased by exposure of blastocysts to 0.2 μM PGE2 or PGF2 or PGF2α, but not to Iloprost. Thus, imbibition of water does not cause blastocyst swelling at least during limited in vitro culture. It is concluded that prostacyclin is of less importance in blastocyst function than PGE2 or PGF2α.
Cytogenetic study of parthenogenetically activated bovine oocytes matured in vivo and in vitro
Authors: King W. A. , Xu K. P. , Sirard M.‐A. , Greve T. , Leclerc P. , Lambert R. D. , Jacques P. 
Published: February 2005

AbstractThree experiments were performed to evaluate the potential for parthenogenetic activation of bovine oocytes in in vitro fertilization systems and to determine the chromosome complement of the resulting parthenogenotes. In the first experiment, immature oocytes from slaughtered cattles were matured in vitro in Defined Medium (DM) for 24 h to simulate in vitro fertilization conditions. Subsequently, a portion was fixed, and the remainder were transferred to rabbit oviducts. Oocytes were then cultured for 6–8 h or for 24 h with Colcemid present during the last 6 to 8 h and fixed on slides and examined. In the second experiment, mature oocytes were collected from the preovulatory follicles, and the oocytes were subjected to the same culture as in experiment I. In the third experiment, oocytes were treated as in experiment II, except that instead of transfer to rabbit oviducts, they were cultured an additional 48 h in vitro. In experiment I, 131 oocytes were fixed after culture in DM. Of the 79 oocytes analyzed in the pre‐rabbit group, 71 (90%) were at the second meiotic metaphase (MII), and 8 (10%) were at pre‐MII stage; none were activated. After transfer to rabbits, 291 were fixed. Of these, 80 were analyzed; 37 (46.3%) were MII, 7 (8.6%) were pre‐MII, and 36 (45%) were activated. Of the 36 activated oocytes, 26 (72.2%) were haploid, 4 (11.1%) were diploid, 1 (12.8%) was tetraploid, and 5 (13.8%) were in the process of endoreduplication. In experiment II, 51 oocytes were fixed after culture in DM of which 36 (70.6%) could be analyzed; 30 (83.3%) were MII, and 6 (16.7%) were pre‐MII. After culture in the rabbit, 68 were fixed of which 27 (39.7%) could be analyzed. Of these 27, 20 (74.1%) were MII, and 7 (25.9%) were activated; 6 were haploid, and 1 was endoreduplicating. In experiment III, 30 oocytes were fixed at the end of the culture period; only 10 could be analyzed of which 8 (80%) were MII and 2 (20%) were pre‐MII. In all, 46% of in vitro and 26% of in vivo matured oocytes were activated, based on chromosomal analysis. Of those activated, the majority (74.4%) were haploid, suggesting that activation occurs at or after completion of MII. Endoreduplication appears to be one of the mechanisms leading to the formation of diploid and polyploid parthenogenotes.
Fertilization cone formation in starfish oocytes: The role of the egg cortex actin microfilaments in sperm incorporation
Authors: Kyozuka Keiichiro , Osanai Kenzi 
Published: February 2005

AbstractThe process of sperm incorporation into starfish (Asterias amurensis) oocytes was examined by electron and fluorescence microscopy. The fertilization cone began to form at the place where the acrosomal process fused with the egg surface and developed into an inverted conical mass containing a small amount of electron‐dense cytoplasm. Microfilaments, which stained with NBD‐phallacidin, were detected in the fertilization cone. Microvillar protrusions from the fully grown fertilization cone engulfed the sperm head outside the fertilization membrane. The sperm organelles were incorporated into the egg cortex with the absorption of the protrusions. Cytochalasin B inhibited sperm incorporation, fertilization cone formation, and actin filament organization. It is suggested that the development and reduction of the fertilization cone, which depend on the functioning of microfilaments, are necessary for sperm incorporation in starfish.
Characterization of the postacrosomal sheath of bovine spermatozoa
Authors: Olson Gary E. , Winfrey Virginia P. 
Published: February 2005

AbstractA purified head fraction was prepared from bovine epididymal spermatozoa and was utilized to identify the solubility characteristics and major polypeptide components of the postacrosomal sheath. Sperm heads extracted in nonionic‐detergent‐containing or high‐salt‐containing solutions retained an intact postacrosomal sheath, but it was readily solubilized by high pH extraction solutions. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis revealed a major polypeptide of 58,000 daltons (58‐kD) in the high pH extract solution. Antibodies to the 58‐kD polypeptide specifically reacted with the postacrosomal segment by immunofluorescence and by electron microscopic immunohistochemistry were shown to bind the postacrosomal sheath. We conclude that this 58‐kD polypeptide is a constituent of the postacrosomal sheath and that its distribution is restricted to the postacrosomal segment.
The acrosome reaction in spermatozoa of the grey‐headed flying fox (Pteropus poliocephalus: Chiroptera) exposes barbed subacrosomal material
Authors: Cummins J. M. , Robson S. K. , Rouse G. W. 
Published: February 2005

AbstractAcrosome reactions were induced in seminal spermatozoa of the megachiropteran Pteropus poliocephalus, the grey‐headed flying fox, using the ionophore A23187 (10 μM in Tyrodes solution with 1% w/v BSA). Samples were taken at 0, 10, and 120 minutes and fixed for electron microscopy. Initial motility of approximately 70% decreased to approximately 10% over 2 hours. The first motile spermatozoa without acrosomal caps were seen after 6 minutes, and by 90 minutes approximately 60% of motile spermatozoa had completed the acrosome reaction. The first sign of the reaction (by TEM) appears to be swelling and cavitation of the acrosomal matrix within the apical and principal segments, followed or possibly accompanied by fusion and fenestration of the outer acrosomal and plasma membranes and dispersion of the matrix except from the equatorial segment. The end‐product of the reaction thus conforms to that seen in other eutherian mammals. However, the reaction exposes a uniquely moulded organization of subacrosomal material (“pseudoperforatorium”), shaped like an anvil over the rostral rim of the flattened nucleus and encased by the remaining inner acrosomal membrane. This has two “lateral” spikes on each side that extend approximately to the same width as the head in the region of the equatorial segment. While these barbs could serve to stabilize or anchor the apical segment of the acrosome, their exposure following the acrosome reaction suggests some specific mechanical role in penetration of the zona pellucida or in protecting more caudal structures from abrasive damage.
Cleavage characteristics of mouse embryos inseminated and cultured after zona pellucida drilling
Authors: Talansky Beth E. , Gordon Jon W. 
Published: February 2005

AbstractThe effects of zona drilling on mouse embryo development in vitro were evaluated. Following insemination, sperm were immediately concentrated at the area of drilling, and in zona‐drilled eggs, pronuclei appeared 30–50 min earlier than in zona‐intact controls. Zona‐drilled oocytes fertilized at significantly higher rates than undrilled controls and, consequently, a greater percentage of eggs inseminated after zona drilling reached the blastocyst stage. The attrition rates of zona‐drilled embryos at each cleavage stage did not differ significantly from controls.Manipulated embryos exhibited unique cleavage patterns. Some embryos lost their zonae entirely, whereas others became partially extruded at early cleavage stages. These anomalies led to separation of blastomeres from the zygote proper, aggregation of embryos to form giant composite morulae and blastocysts, and occasionally to formation of miniature twin blastocysts. These characteristics of cleavage indicate that although zona drilling of a cohort of oocytes is likely to lead to an increased number of live births relative to controls, some developmental abnormalities can be encountered, and these may be associated with embryo loss, spontaneous chimerism, or possibly with conception of monozygotic twins.
Xenopus spermatozoon: Is there any correlation between motility and oxygen consumption?
Authors: Bernardini Giovanni , Belgiojoso Pio , Camatini Marina 
Published: February 2005

AbstractThe motility status of Xenopus laevis spermatozoa does not affect their respiration rate. Oxygen consumption for 109 spermatozoa is approximately 0.4 μmol/minute. Oxygen consumption is not increased by gramicidin D, an uncoupler, and it is not blocked by KCN or NaN3. The adenosine triphosphate (ATP) content of spermatozoa that have been activated is definitely less than that in the spermatozoa that remained immotile. Incubation in KCN, NaN3, and gramicidin decreases the ATP content and impairs motility. The conclusions of the present study are that in Xenopus spermatozoa motility and oxygen consumption are not correlated, and the composition of the respiratory chain of these spermatozoa presents noteworthy peculiarities.
Segregation products of male mice doubly heterozygous for the RB(6.16) and RB(16.17) translocations: Influence of sperm karyotype on fertilizing competence under varying mating frequencies
Authors: Zackowski Joleen L. , Martin‐DeLeon Patricia A. 
Published: February 2005

AbstractThe meiotic segregants of male mice heterozygous for Rb(6.16)24Lub and Rb(16.17)7Bnr were viewed, for the first time, at first cleavage metaphase. Chromosomes were analyzed after G‐banding, C‐banding, and karyotyping. To study sperm aging effects, chromosomes of 202 one‐cell zygotes derived from males mating at intervals of approximately 3,14, and 21 days were examined. At least 89.6% of sperm‐derived complements were products of 2:2 segregation; at most, a possible 6.4% were 3:1 segregants. The six expected types of 2:2 segregants, both balanced and unbalanced, were equifrequent in the total zygote population derived from sperm of all ages. When the data were analyzed according to mating frequency, the 3‐day sperm population considered most likely to be fresh showed a deficiency of the segregant nullisomic for chromosome 6 and disomic for chromosome 17, when compared with the reciprocal segregant (P < 0.025) as well as to all other 2:2 segregants (P < 0.05). However, these sperm fertilized in greater numbers (P < 0.01) than their reciprocal segregant (disomic for 6 and nullisomic for 17) in the 14‐day sperm population. While sperm with chromosomal abnormalities are capable of fertilization, the competence of segregants nullisomic for 6 and disomic for 17 apparently depends on the prior storage period in the male. Further, the results suggest that the effect of aneuploidy on sperm function is dependent on the specific chromosome(s) involved.
Preimplantation mammalian aggregation and injection chimeras
Authors: Prather Randall S. , Hagemann Lora J. , First Neal L. 
Published: February 2005

AbstractThe preimplantation embryo is highly resilient to experimental manipulations. A specific manipulation that has revealed many clues to the developmental process is chimera production. Chimeras have been used to describe the importance of developmental characteristics of embryonic cells and how these characteristics are involved with developmental fate. These characteristics have been monopolized in the production of interspecific chimeras and the production of transgenic animals. This review attempts to discuss the major factors affecting preimplantation mammalian embryo chimera production.
Effects of ultrasound on ovulation in the mouse
Authors: Heyner S. , Abraham V. , Wikarczuk M. L. , Ziskin M. C. 
Published: February 2005

AbstractIn vitro fertilization and embryo transfer (IVF–ET) programs use ultrasound extensively for monitoring the growth of ovarian follicles and, subsequently, for confirming the presence of a fetal sac. There have been few reports of the effects of ultrasound on ovulation rates in mammals, and we report here that following exposure to continuous wave ultrasound at a spatial average intensity of 3.0 W/cm2 for five minutes, ovulation rates measured 10 days later were significantly reduced in mice. When temperature elevation of the exposed ovary was measured with a thermocouple, hyperthermia correlated with reduction in ovulation.
Development of single blastomeres from four‐ and eight‐cell mouse embryos fused into the enucleated half of a two‐cell embryo
Authors: Kono T. , Tsunoda Y. 
Published: February 2005

AbstractSingle blastomeres from four‐ and eight‐cell mouse embryos were fused into the enucleated halves of two‐cell embryos, and the ability of these reconstituted embryos to develop in vitro and in vivo was examined. The proportion of these reconstituted embryos developing to blastocysts was 74% (60/81) when four‐cell embryo blastomeres were used as nuclei donors and 31% (57/182) when eight‐cell embryo blastomeres were used. Eight complete sets of the quadruplet‐reconstituted embryos developed to blastocysts, and five live young (9%, 5/57) were obtained after transfer; however, none of the live young were clones. Although when using blastomeres from eight‐cell embryos no complete set of eight developed to blastocysts, sextuplets were obtained. The blastocysts, however, failed to produce live young after transfer. In assessing the outgrowths, it was found that 43% of those derived from reconstituted embryos using blastomeres from four‐cell embryos had an inner cell mass (ICM); however, outgrowths derived from reconstituted embryos using blastomeres from eight‐cell embryos lacked an ICM. These results suggest that the genomes of four‐ and eight‐cell nuclei introduced into the enucleated halves of two‐cell embryos are reversed to support the development of the reconstituted embryo.
Sperm morphology and storage in the female reproductive tract of the fat‐tailed dunnart, Sminthopsis crassicaudata (Marsupialia: Dasyuridae)
Authors: Breed W. G. , Leigh C. M. , Bennett J. H. 
Published: February 2005

AbstractA study of spermatozoa in the isthmus of the oviduct and of the surrounding epithelial cells in the dasyurid marsupial, Sminthopsis crassicaudata, was carried out. At least 10% of the ejaculated spermatozoa probably populate the isthmus region, where many come to reside in crypts until around the time of ovulation. Ultrastructural observations of spermatozoa in this region indicated that they had intact acrosomes and were identical in their morphology with those in the cauda epididymidis. After ovulation spermatozoa rapidly disappeared, some of which may be phagocytosed by the cells lining the crypts. These epithelial cells were also found to have many large, electron‐dense granules at the time of sperm storage, but the contents did not appear to be released until the zygotes passed along the tract. The secretory activity of these cells may thus relate more to the production of the shell membrane that comes to surround the zygote than to the cells performing a nutritive or protective function for the spermatozoa during their period of storage within the female reproductive tract.
Role of glutathione peroxidase in protecting mammalian spermatozoa from loss of motility caused by spontaneous lipid peroxidation
Authors: Alvarez Juan G. , Storey Bayard T. 
Published: February 2005

AbstractMouse and human spermatozoa, but not rabbit spermatozoa, have long been known to be sensitive to loss of motility induced by exogenous H2O2. Recent work has shown that loss of sperm motility in these species correlates with the extent of spontaneous lipid peroxidation. In this study, the effect of H2O2 on this reaction in sperm of the three species was investi gated. The rate of spontaneous lipid peroxidation in mouse and human sperm is markedly enhanced in the presence of 1‐5 mM H2O2, while the rate in rabbit sperm is unaffected by H2O2. The enhancement of lipid peroxidation, the rate of reaction of H2O2 with the cells, the activity of sperm glutathione peroxidase, and the endogenous glutathione content are highest in mouse sperm, intermediate in human sperm, and very low in rabbit sperm. Inac tivation of glutathione peroxidase occurs in the presence of H2O2 due to complete conver sion of endogenous glutathione to GSSG: No GSH is available as electron donor substrate to the peroxidase. Inactivation of glutathione peroxidase by the inhibitor mercaptosucci nate has the same effect on rate of lipid peroxidation and loss of motility in mouse and human sperm as does H2O2. This implies that H2O2 by itself at 1‐5 mM is not intrinsically toxic to the cells. With merceptosuccinate, the endogenous glutathione is present as GSH in mouse and human sperm, indicating that the redox state of intracellular glutathione by itself plays little role in protecting the cell against spontaneous lipid peroxidation. Mouse and human sperm also have high rates of superoxide production. We conclude that the key intermediate in spontaneous lipid peroxidation is lipid hydroperoxide generated by a chain reaction initiated by and utilizing superoxide. Removal of this hydroperoxide by gluta thione peroxidase protects these sperm against peroxidation; inactivation of the peroxidase allows lipid hydroperoxide to increase and so increases the peroxidation rate. Rabbit sperm have low rates of superoxide reaction due to high activity of their superoxide dismutase; lack of endogenous glutathione and low peroxidase activity does not affect their rate or lipid peroxidation. As a result, these sperm are not affected by either H2O2 or mercapto‐succinate. These results lead us to postulate a mechanism for spontaneous lipid peroxida tion in mammalian sperm which involves reaction of lipid hydroperoxide and O2 as the rate‐determining step.
Characterization of cell surface polypeptides of unfertilized, fertilized, and protease‐treated zona‐free mouse eggs
Authors: Boldt Jeffrey , Gunter L. E. , Howe Anita M. 
Published: February 2005

AbstractThe polypeptide composition of unfertilized, fertilized, and protease‐treated zona‐free mouse eggs was evaluated in this study. Zona‐free eggs were radioiodinated by an Iodogen‐catalyzed reaction. Light microscopic autoradiography of egg sections revealed that labeling was restricted to the cell surface. Labeled eggs were solubilized, and cell surface polypeptides were identified by one‐dimensional SDS polyacrylamide gel electro‐phoresis and autoradiography. The unfertilized egg demonstrated 8–10 peptides that incorporated125I, with major bands observed at approximately 145–150, 94, and 23 kilo‐daltons (kD). Zona‐free eggs fertilized in vitro and then radiolabeled demonstrated several new bands in comparison to unfertilized eggs, with a major band appearing at approxi mately 36 kD. Treatment of radiolabeled unfertilized eggs with either trypsin or chymo‐trypsin (1 mg/ml for 5–20 min) caused enzyme‐specific modifications in labeled polypep tides. Trypsin (T) treatment resulted in time‐dependant modification of the three major peptides at 145–150,94, and 23 kD. Chymotrypsin (CT) treatment, in contrast, was asso ciated with loss or modification of the 94 kD band, with no apparent effect on either the 145–150 or 23 kD band. Taken together with previous data indicating that T or CT egg treatment interferes with sperm‐egg attachment and fusion (Boldt et al.: Biol Reprod 39:19–27, 1988), these results suggest a possible role for the 94 kD protein in sperm‐egg interaction.
In vitro fertilization in the sheep: Effect of elevated calcium concentration at insemination
Authors: Huneau D. , Crozet N. 
Published: February 2005

AbstractOocytcs (n = 273), collected from superovulated ewes, were inseminated with in vitro capacitated spermatozoa from four rams [Crozet et al., 1987]. In each experiment, paral lel insemination was performed using aliquants from a single ejaculate in either our stan‐dard fertilization medium DM‐H‐SS (a modification of Bracken's defined medium, buffered with HEPES and containing 20% v/v sheep serum) or in the same medium supplemented with calcium lactate (DM‐H‐SS + Ca). The measured total calcium con centrations were Ca++T = 2.74 mM in DM‐H‐SS medium and Ca++T = 8.74 mM in DM‐H‐SS + Ca; the ratio of free to total calcium in DM‐H‐SS was Ca++F/Ca++T = 0.85. Fertilization was assessed at 17 hours postinsemination.Variations in the ejaculates were observed for each of the four rams tested. When DM‐H‐SS + Ca was used, the percentages of fertilized (75% vs. 50%) and monospermic (58% vs. 41%) eggs were significantly enhanced compared with use of DM‐H‐SS. No improve ment was observed in control medium DM‐H‐SS + lac containing neutralized lactic acid. Supplementing the fertilization medium with calcium had no apparent effect on the inci dence of polyspermy.These experiments show that the fertilization rate achievable in vitro by individual ejaculates from various rams can be increased by raising the calcium concentration in the fertilization medium to a value much higher than that present in tuba! fluids from estrous ewes. Extended incubation in such a high calcium concentration is unnecessary for in vitro capacitation of ram spermatozoa.
Primordial germ cell development in cultures of dispersed central disks of stage X chick blastoderms
Authors: Ginsburg Malka , Eyal‐Giladi Hefzibah 
Published: February 2005

AbstractCentral disk fragments cut from stage X chick blastoderms were dispersed and cultured on glass coverslips. After 48 hr of incubation the cultures showed various degrees of organization into three‐layered aggregates in which no axis development was observed. Primordial germ cells (PGCs) were detected in ail cultures. The number of PGCs was found to be correlated to the initial cell concentration in the suspension. By regression analysis it was found that in cultures initiated from 10 central disks or more, the mean number of PGCs per fragment was constant and matched the number of PGCs found for intact control central disks incubated for the same length of time. It appears that in cultures of stage X, the morphologic expression of PGCs is related to the level of differentiation and organization of the somatic cells in the culture, which, in turn, is dependent on the initial concentration of cells in the culture.