bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preimplantation embryo development and serum steroid levels in immature rats induced to ovulate or superovulate with pregnant mares' serum gonadotropin injection or follicle‐stimulating hormone infusions
Authors: Leveille M.‐C. , Armstrong D. T. 
Published: February 2005

AbstractFollicular stimulation protocols using pregnant mares' serum gonadotropin (PMSG) or a follicle‐stimulating hormone (FSH) preparation were compared to evaluate the yield and quality of embryos obtained from immature rats. Rats received a superovulatory dose of PMSG (401U), a nonsuperovulatory dose of the same gonadotrophin (4 IU), or a continu ous s.c. infusion over a 72‐h period with a purified FSH preparation containing an opti mum ratio of luteinizing hormone (LH): FSH (FSH‐hCG). The females were caged with fertile males on the evening of the 3rd day of gonadotropin treatment and scored for the occurrence of mating on the next morning; subgroups were killed on days 1–4 of preg‐nancy. High fertilization rates were observed in rats treated with 4 IU PMSG (84.1%) and in rats infused with FSH‐hCG (91.0%); however, a much lower fertilization rate was observed following treatment with 40 IU PMSG (41.5%). From median ovulation rates of 9 and 79 in rats treated with 4 IU PMSG and in rats infused with FSH‐hCG, medians of 8 and 69 embryos, respectively, were recovered from reproductive tracts flushed on day 4 of pregnancy, from which 75% were morulae or blastocysts; in contrast, from a median ovu lation rate of 42.5, a median of only 12 embryos was recovered on day 3 of pregnancy following superovulation with 40 IU PMSG of which 80% were degenerate ova. Serum steroid profiles during the first 4 days of pregnancy differed significantly among treatment groups, the major differences being in substantially elevated levels of estradiol and andro‐gens on days 1–3 in rats receiving the high (40 IU) dose of PMSG. Levels of these steroids in rats superovulated with the FSH‐hCG infusion regimen were only marginally elevated above levels observed in rats treated with the low (4 IU) nonsuperovulatory dose of PMSG. Consistent with high ovulation rates, serum progesterone levels rose to considera bly higher levels during the period in both superovulated groups than in animals receiving the low, nonsuperovulatory dose of PMSG. This work describes a novel method to superovulate rate (FSH‐hCG) leading to high yields of normally developing embryos at all preimplantation stages and illustrates the close association between high yield of emyryos and low levels of circulating andorgens and estradiol‐17β during the preimplantation period.
Effects of a superovulatory dose of pregnant mare serum gonadotropin on follicular steroid contents and oocyte maturation in rats
Authors: Yun Young W. , Yu Frank H. , Yuen Basil Ho , Moon Young S. 
Published: February 2005

AbstractOur previous study has shown that superovulatory treatment with pregnant mare serum gonadotropin (PMSG) in rats caused marked alterations in ovarian and serum steroid responses and coincidental increase in degenerate oocytes (Yun et al., 1987). This study examined the effects of superovulatory treatment (20 IU PMSG) on follicular steroid contents and oocyte maturation. Immature female rats aged 28‐30 days were injected with 4 or 20 IU PMSG and sacrificed at 24, 48, 60, and 72 hr. Compared to control regimen, follicular content of progesterone (P) in superovulated rats significantly (P < .05) increased at 48 hr. Androgen (A) content significantly (P < .01) decreased below control level at 24 hr but significantly (P < .05) increased above control level at 48 hr and 60 hr. There was no significant change in 17β‐estradiol (E) content between the two groups. In control regimen, the ratio of A/E sharply decreased and the ratios of P/Eand P/A increased steadily from 24 hr. However, superovulatory regimen showed a consistently steady state in the overall ratios of follicular steroids after 24 hr. Nuclear maturation of the majority of control oocytes recovered from oviducts at 72 hr was synchronized at metaphase II, whereas superovulated oocytes displayed different stages varying from prophase I to metaphase II at 24, 48, and 72 hr. The results provide direct evidence of atypical ovulations in superovulated oocytes with premature or asynchronous nuclear maturation and demonstrate a close relationship between meiotically aberrant oocytes and abnormal follicular steroidogenesis following superovulation with PMSG in rats.
Analysis of the first cell cycle in the cross between hamster eggs and human sperm
Authors: Brandriff B. F. , Gordon L. A. 
Published: February 2005

AbstractGolden hamster eggs fused with human sperm were pulsed with bromodeoxyuridine to determine the timing of S‐phase and the length of the first ceil cycie in this hybrid cross. Fused eggs were fixed and pronuclei scored for incorporation of the thymidine analogue detected by indirect immunofiuorescence. Although S‐phase started synchronously 3–3.5 hr after coincuba‐tion of sperm and eggs, its duration was variable such that two‐cell stages appeared at 16 hr while a proportion of pronuclei was still engaged in DNA synthesis. Unlike rodent sperm chromatin, human sperrn chromatin was able to participate in DNA synthesis well before its maturation into a fully developed pronucleus. Human sperm chromatin appears able to function under conditions different in several respects from those in human eggs.
Modulation of phagocytic activity in cultured sertoli cells
Authors: Filippini A. , Russo M. A. , Palombi F. , Bertalot G. , De Cesaris P. , Stefanini M. , Ziparo E. 
Published: February 2005

AbstractPhagocytic activity of rat Sertoli cells that were cultured in vitro has been evaluated as the ability to internalize polystyrene beads. Our data demonstrate that these ceils are active phagocytes and that such phagocytic activity is under negative control by follicle‐stimulating hormone (FSH). The hormonal control is mediated by increased intracellular levels of cAMP. Moreover Sertoli cdl responds to tuftsin, an oligopeptide known to act only on macrophages and granulocytes, by increasing up to five times its phagocytic activity. Phagocytic uptake of polystyrene beads is associated with dramatic changes of the cellular shape. Such morphological modifications are significantly reduced under FSH stimulation. The physiological implications of the data are discussed.
Membrane specializations associated with the acrosomal complex of sea urchin sperm as revealed by immunocytochemistry and freeze fracture replication
Authors: Longo Frank J. , Georgiou Christos , Cook Susan 
Published: February 2005

AbstractObservations, employing freeze fracture replication and electron microscopic imrnunochemis‐try, have been carried out to determine structural correlations of the plasma membrane domain occupied by a 210 kDa protein involved in the acrosomal reaction of sea urchin sperm and recognized by the monoclonal antibody, J10/14 (Trimmer et al: Cell 40:697–703, 1985; Proceedings of the National Academy of Sciences of the United States of America 83: 9055–9059, 1986). Immunogold‐J10/14 staining of acrosorne‐intact sperm was intense along the flagellum and a narrow collar just posterior to the sperm apex that surrounded the acrosomal complex (acrosomal vesicle and subjacent anterior nuclear fossa containing g‐actin). Counts of gold particles revealed a density (average number of particles/μm2 of surface area) eightfold greater along the plasma membrane associated with the acrosomal complex than membrane delimiting the remainder of the sperm head. The collar of J10/14 staining was isomorphic with a dense aggregation of intramembranous particles in the P‐face of the plasma membrane and a thin cytoplasmic region that surrounded the acrosomal complex. In acrosomc‐reacted sperm, intense J10/14 staining was distributed along the flagellum and sperm head; prominent anterior staining was not apparent in all specimens. The density of gold particles associated with plasma membrane delimiting components of the former acrosomal complex, nucleus and mitochondrion, as well as the total average number of particles along the entire sperm surface, were increased in sperm acrosome‐reacted with A‐23187. Concomitant with this change in staining was the disappearance/reduction of the collars of intramembranous particles and cytoplasm. These observations indicate that plasma membrane components (210 kDa protein and intramembranous particles) and the collar of cytoplasm which are associated with the acrosomal complex are functionally, as well as structurally related. Analyses of particle density distributions along acrosome‐ and non‐acrosome‐reacted sperm suggest that the different staining patterns observed may be brought about by the recognition of cryptic sites at the time of the acrosomal reaction.
On the number and rate of formation of sperm‐zona bonds in the mouse
Authors: Baltz Jay M. , Cardullo Richard A. 
Published: February 2005

AbstractIn mammalian fertilization, sperm bind to the zona pellucida, a glycoprotein matrix forming a shell surrounding the oocyte. Subsequently, one of the bound sperm penetrates the zona and fertilizes the egg. The adhesion between sperm and zona is mediated by complementary receptor‐ligand pairs. Recent biochemical evidence has identified likely candidates for these molecules in the mouse. Biophysical studies have predicted that very few (possibly as few as one) bonds are needed to tether a motile sperm to the zona. We have used the data characterizing the putative receptors of the mouse sperm to predict the number of bonds they can form with the zona ligands. Our calculations indicate that few bonds probably form between the sperm and zona during the initial contact when the sperm is captured, supporting the hypothesis that fertilization depends on the action of a very few sperm‐zona bonds.
Hamster oocyte penetration tests with oocytes frozen in propanediol: Comparison with non‐frozen oocytes
Authors: Sachs H. Hyatt , Pink M. J. , Gwatkin R. B. L. 
Published: February 2005

AbstractHamster oocytes were frozen using a 1,2‐propanediol‐sucrose procedure, which resulted in over 90% survival. After thawing and zona removal the oocytes were compared with non‐frozen oocytes in a zona‐free hamster egg test employing spermatozoa from human semen donors and suspected infertility patients. Similar data were obtained, indicating that propancdiol‐sucrose frozen hamster eggs may be used in place of fresh eggs for convenience and to a void scheduling problems.
Developmental capacity of mouse oocytes that undergo maturation in vitro: Effect of the hormonal state of the oocyte donor
Authors: Schroeder Allen C. , Eppig John J. 
Published: February 2005

AbstractIn a previous study, it was shown that cumulus cell‐enclosed germinal vesicle (GV)‐stage oocytes, isolated from pregnant mares' serum gonadotropin (PMSG)‐primed immature (22–24 day old) mice and that underwent spontaneous maturation in vitro, exhibited frequencies of embryonic development similar to oocytes stimulated to mature and ovulate in vivo by administration of gonadotropins [Schroeder AC, Eppig JJ, (1984) Dev Biol 102:493–497]. In the present study, the effect of the hormonal state of the oocyte donor on the capacity of in vitro matured oocytes to be fertilized and undergo pre‐ and post‐implantation development was explored further. Oocytes were isolated at the GV‐stage from the following groups of mice: 1) unprimed immature mice; 2) adult cycling mice; 3) unprimed Snell dwarf (dw) mice that have undetectable levels of growth hormone (GH), prolactin, and thyroid‐stimulating hormone (TSH); and 4) primed and unprimed hypogonadal (hpg) mice that have undetectable levels of circulating gonadotropins. Oocytes maturing in vitro after isolation from normal unprimed immature or adult mice at all stages of the estrous cycle acquired full developmental capacity. GV‐stage oocytes isolated from dwarf mice showed embryonic development equivalent to normal ( + /?) littermate controls. Therefore, GH, TSH, or prolactin are not required during oogencsis in vivo to promote the acquisition of competence to complete embryogenesis after maturation in vitro. Oocytes from hypogonadal mice had a much reduced capacity for preimplantation development when compared with normal littermates. Administration of PMSG to the hypogonadal mice significantly increased the developmental capacity of oocytes that underwent maturation in vitro. Gonadotropins, therefore, have a beneficial effect on the oocytc's capacity for embryonic development.
Octaploid mouse embryos produced by electrofusion polarize and cavitate at the same time as normal embryos
Authors: Winkel Glen K. , Nuccitelli Richard 
Published: February 2005

AbstractWe created enlarged octaploid mouse blastomeres by subjecting four‐cell embryos to a large (>2.000 V/cm) dc field of brief duration (10 μsec). This electrofusion pulse caused three to four of the blastomcres to fuse in 60% of the embryos tested. Modifications of fusion chamber and medium enabled fusion of up to 20 embryos per pulse, greatly increasing the yield for this fusion method. The effectiveness of the electrofusion pulse depended upon such parameters as embryonic cell cycle time and the pH and temperature of the electrofusion medium. There was no discernable lag in the onset of the third cleavage division or the time of cavitation in fused blastomeres. These fused blastomeres also underwent polarization of their apical surfaces at the same time as controls in spite of their increased cell size. These results suggest that octaploid mouse blastomeres created via electrofusion divide normally through the blastocyst stage and polarize at the same time and in the same sequence as smaller control blastomeres. This suggests that the mechanisms underlying cell division, cavitation, and cortical polarization are not affected by changes in cellular size or ploidy.
Growth and development of rat oocytes in vitro
Authors: Daniel Susan A. J. , Armstrong David T. , Gore‐Langton Robet E. 
Published: February 2005

AbstractRat oocytes from preantral follicles have been shown to grow and acquire meiotic competence in vitro. Follicles were isolated by enzymatic digestion of ovaries from infant (10‐ or 11‐day‐old) Wistar rats. Follicles were cultured for up to 20 days in Minimum Essential Medium (MEM) supplemented with 2 mM hypoxanthine to maintain meiotic arrest. When cultures were begun, oocytes were in midgrowth phase (40–45 μm diameter), and were incapable of undergoing meiotic maturation when placed in hypoxanthine‐free MEM. Oocytes grew and acquired meiotic competence during culture for 20 days attaining mean diameters of 62. 6 ± 0.6 μm and 61.1 ± 0.6 μm in two experiments. Germinal vesicle breakdown (GVB) occurred in 60–70% of oocytes when transferred to MEM without hypoxanthine. Concomitant with oocyte growth and maturation were spontaneous increases in follicular production of progestins, androgens and estrogens. When oocytes grown and matured in this system were inseminated in vitro with epididymal sperm, 36.1% and 25.8% were penetrated by one or more sperm in two experiments. However, fertilization was not generally normal with multiple penetrations and abnormal numbers of pronuclei (one or three) being common, suggesting that in these oocytes cytoplasmic maturation was incomplete or abnormal. In the two experiments, normal fertilization (two pronuclei and one sperm tail in the vitellus) occurred in 34.6% and 47 1% of penetrated oocytes with development of these apparently normal zygotes to two‐cell embryos being 66.7% and 62.5%, respectively.
Effects of protein kinase C stimulation and free Ca2+ rise in mammalian egg activation
Authors: Colonna R. , Tatone C. , Malgaroli A. , Eusebi F. , Mangia F. 
Published: February 2005

AbstractProtein phosphorylation activity, chromosome segregation, and cortical granule exocytosis (CGE) have been studied in mouse eggs activated parthenogeneticaliy by specific PKC stimulators such as 4β‐phorbol 12‐myristate 13‐acetate (PMA) and l‐oleyl‐2‐acetylglycerol (OAG), or by agents inducing an immediate increase in cytosolic calcium concentration ([Ca2+]i) such as ethanol and Ca‐ionophore A23187. When protein phosphorylation activity of mouse eggs was analyzed 10 min after different activation treatments, the phosphorylation of a 32 kDa polypeptide was a feature common to all different parthenogenetic agents used. The appearance of such labeling was independent of an increasing [Ca2+]i, as indicated by direct measurements of i) cytosolic Ca2+ concentration with fura‐2 and 2) exogenous Ca2+ entrance into activated eggs. Emission of the second polar body was blocked in PMA‐elicited partheno‐genones, whereas it was apparently normal in OAG‐treated eggs, unless the eggs were continuously exposed to OAG. CGE was almost immediate in ethanol‐activated eggs, but in PMA‐treated cells, it occurred significantly later, with a timing corresponding to that found for the appearance of sustained Ca2+ oscillations in this system. Here, we propose that in mammalian eggs 1) PKC stimulation represents an early regulatory step in egg activation; 2) this kinase activity is turned off before the second meiotic cleavage; and 3) cytosolic free Ca2+ rise is essential for CGE occurrence.
Role of spermatozeugmata in the spawning ecology of the brooding oyster Ostrea edulis
Authors: Foighil Diarmaid Ó 
Published: February 2005

AbstractOstrea edulis spawns spermatozeugmata, each composed of radially arrayed sperm cells attached by an extracellular matrix (ECM) to a core of acellular vesicles. The acellular vesicles arc formed from excess nuclear and plasma membranes produced during spermatid condensation, and the ECM is topologically restricted to the interstices between acellular vesicles and sperm heads, being absent from the flagellar surface. When released into seawater, spermatozeugmata retain their structural integrity for varying periods (up to 24 hours) and become demersally distributed in still water. The flagella activate, initially beating in a non‐synchronized, languid manner; however, both the tempo and amplitude of the flagellar action gradually increase to resemble that of typical ‘primitive’ sperm once the cells are released from the spermatozeugma. This increase in flagellar activity and subsequent gamete release coincide with an erosion of the ECM and suggest that the ECM may modulate sperm motility in addition to adhering the cells to the spermatozeugma. Sperm are capable of fertilizing eggs only after dissociating from the spermatozeugma. The net effect of spermatozeugma formation in Ostrea edulis may be the retention of viable sperm in high concentrations at the benthic/ water column interface for prolonged periods after spawning, at least in low current regimes. Unfertilized O. edulis eggs are also concentrated at this location, in the inhalent chambers of female oysters. Spermatozeugmata are entrained by the inhalent current of females and carried into the brood chamber where fertilization occurs. The Ostrea edulis spermatozeugma likely functions as an efficient sperm transfer mechanism if two conditions are met: 1) eggs are retained as broods within benthic females, 2) egg masses are at intermediate distances from spawning males.
Ultrastuctural and cytochemical study of spermatogenesis in Scrobicularia plana (Mollusca, Bivalvia)
Authors: Sousa Mário , Corral Laura , Azevedo Carlos 
Published: February 2005

AbstractThe ultrastructure of the mature spermatozoa and spermatogenesis of the bivalve Scrobicularia plana are described. Support cells extend from the basal lamina to the lumen of the testis and are laterally connected to the germinal epithelium. Germ cells present intercellular bridges and flagella since the spermatogonial stage. While spermatogonia and spermatocytes appear connected to support cells by desmosome‐like junctions, elongated spermatids are held at the acrosomal region by support cell finger‐like processes. During spermiogenesis, the acrosomal vesicle differentiates from a golgian saccule and then migrates to the nuclear apex. A microtubular manchette arising from centrioles surrounds the acrosomal vesicle, the nucleus, and the mitochondria at the time these three organelles start their elongation, disappearing after that. The mature spermatozoon of S. plana lacks a distinct midpiece because the mitochondria extend from the region of the pericentriolar complex along the nucleus anteriorly for approximately 1.4 μm. The features of this bivalve type of modified spermatozoon are compared with those of other animal groups having similar modifications.
Effect of sulfated glycoconjugates on capacitation and the acrosome reaction of bovine and hamster spermatozoa
Authors: Parrish J. J. , Susko‐Parrish J. L. , Handrow R. R. , Ax R. L. , First N. L. 
Published: February 2005

AbstractThe effects of sulfated glycoconjugates on the preparation of mammalian sperm for fertilization were investigated. The three sulfated glycoconjugates tested were heparin, dextran sulfate, and the fucose sulfate glycoconjugate (FSG) from the sea urchin egg jelly coat. In vivo, FSG induces the acrosome reaction in sea urchin sperm. Bovine sperm were found to be capacitated by heparin and FSG as judged both by ability of lysophosphatidylcholine (LC) to induce an acrosome reaction and by ability to fertilize bovine oocytes in vitro. The mechanism by which heparin or FSG capacitated bovine sperm appeared similar, since glucose inhibited capacitation by both glycoconjugates. In contrast to effects on bovine sperm, heparin and FSG induced the acrosome reaction in capacitated hamster sperm. When hamster sperm were incubated under noncapacitating conditions, heparin had no effect on capacitation or the acrosome reaction. Three molecular weights (MW) of dextran sulfate (5,000, 8,000, 500,000) were found to capacitate bovine sperm as judged by the ability of LC to induce an acrosome reaction. Whereas bovine sperm incubated with 5,000 or 8,000 M W dextran sulfate fertilized more bovine oocytes than control sperm (P <0.05), sperm treated with 500,000 M W dextran sulfate failed to penetrate oocytes. The high‐MW dextran sulfate appeared to interact with the zona pellucida and/or sperm to prevent sperm binding. Results suggest that sulfated glycoconjugates may prepare sperm for fertilization across a wide range of species.