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Cleavage Stages (cleavage + stage)
Kinds of Cleavage Stages Selected AbstractsCloning and characterization of cDNA for syndecan core protein in sea urchin embryosDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5 2000Kazuo Tomita The cDNA for the core protein of the heparan sulfate proteoglycan, syndecan, of embryos of the sea urchin Anthocidaris crassispina was cloned and characterized. Reverse transcription,polymerase chain reaction (RT-PCR) was used with total ribonucleic acid (RNA) from late gastrula stage embryos and degenerate primers for conserved regions of the core protein, to obtain a 0.1 kb PCR product. A late gastrula stage cDNA library was then screened using the PCR product as a probe. The clones obtained contained an open reading frame of 219 amino acid residues. The predicted product was 41.6% identical to mouse syndecan-1 in the region spanning the cytoplasmic and transmembrane domains. Northern analysis showed that the transcripts were present in unfertilized eggs and maximum expression was detected at the early gastrula stage. Syndecan mRNA was localized around the nuclei at the early cleavage stage, but was then found in the ectodermal cells of the gastrula embryos. Western blotting analysis using the antibody against the recombinant syndecan showed that the proteoglycan was present at a constant level from the unfertilized egg stage through to the pluteus larval stage. Immunostaining revealed that the protein was expressed on apical and basal surfaces of the epithelial wall in blastulae and gastrulae. [source] Blastocyst embryo transfer is the primary determinant for improved outcomes in oocyte donation cyclesJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 2 2010Natalie Porat Abstract Aim:, Using oocyte donation cycles as an ideal model, we sought to compare pregnancy and implantation rates in cleavage stage (day 3) versus blastocyst stage (day 6) embryo transfers (ET); assess the predictive value of blastocyst formation rates based on cleavage cell stage and morphology grade; and evaluate the ability to predict formation of high quality (HQ) blastocysts. Methods:, Ninety three consecutive oocyte donation cycles from July 2003 to August 2005 were retrospectively evaluated and analyzed to determine if either resulted in a cleavage stage (n = 30) or blastocyst (n = 45) ET. The primary outcomes measured pregnancy rates, the percent development of HQ blastocysts based on day 3 embryo status, and the ability to select day 3 embryos suitable for transfer among four blinded evaluators by assessing their day 6 embryo outcome. Results:, Cleavage stage ET resulted in significantly lower pregnancy rates, clinical pregnancy rates, and implantation rates (47% [n = 14/30]; 40% [n = 12/30] and 27 ± 7%) compared to blastocyst stage (82% [n = 37/45]; 73% [n = 33/45] and 64 ± 6% [±SE], P < 0.01). In total, HQ blastocysts resulted from high and good quality day 3 embryos 35% (191/546) and 17% (93/546), respectively. Blinded evaluation revealed at least one, two or all three day 3 embryos were correctly selected for ET on day 6, 97%, 67% and 19%, respectively. Conclusion:, Day 6 ET resulted in significantly better clinical outcomes compared to day 3 ET. While day 3 status is not predictive of blastocyst quality, the selection of at least one day 3 embryo ultimately suitable for blastocyst ET underscores the significance of optimal endometrial receptivity. [source] Precambrian animal life: Taphonomy of phosphatized metazoan embryos from southwest ChinaLETHAIA, Issue 2 2005DORNBOS STEPHEN Phosphatized fossils from the Neoproterozoic Doushantuo Formation have provided valuable insight into the early evolution of metazoans, but the preservation of these spectacular fossils is not yet fully understood. This research begins to address this issue by performing a detailed specimen-based taphonomic analysis of the Doushantuo Formation phosphatized metazoan embryos. A total of 206 embryos in 65 thin sections from the Weng'an Phosphorite Member of the Doushantuo Formation were examined and their levels of pre-phosphatization decay estimated. The data produced from this examination reveal a strong taphonomic bias toward earlier (2-cell and 4-cell) cleavage stages, which tend to be well-preserved, and away from later (8-cell and 16-cell) cleavage stages, which tend to exhibit evidence for slight to intense levels of organic decay. In addition, the natural abundances of these embryos tend to decrease with advancement in cleavage stage, and no evidence of more advanced (beyond 16-cell) cleavage stages or eventual adult forms were found in this study. One possible explanation for this taphonomic bias toward early cleavage stages is that later cleavage stages and adult forms were more physically delicate, allowing them to be more easily damaged during burial and reworking, allowing for more rapid decay. The spectacular preservation of these embryos was probably aided by their likely internal enrichment in phosphate-rich yolk, which would have caused their internal dissolved phosphate levels to reach critical levels with only miniscule organic decay, thereby hastening phosphatization. If internal sources of phosphate did indeed play a role in the phosphatization of these embryos, it may explain their prolific abundance in these rocks compared to other phosphatized fossils as well as indicating that metazoans lacking such internal phosphate sources were likely much more difficult to preserve. The phosphatic fossils of the Doushantuo Formation, therefore, provide an indispensable, yet restricted, window into Neoproterozoic life and metazoan origins. [source] Hibernation as a far-reaching program for the modulation of RNA transcriptionMICROSCOPY RESEARCH AND TECHNIQUE, Issue 8 2008Manuela Malatesta Abstract In eukaryotic cells, pre-mRNAs undergo several transformation steps to generate mature mRNAs ready to be exported to the cytoplasm. The molecular and structural apparatus for mRNA production is generally able to promptly respond to variations of metabolic demands. Hibernating mammals, which periodically enter a hypometabolic state, represent an interesting physiological model to investigate the adaptive morpho-functional modifications of the pre-mRNA transcriptional and processing machinery under extreme metabolic conditions. In this study, the subnuclear distribution of some transcriptional, splicing, and cleavage factors was investigated by ultrastructural immunocytochemistry in cell nuclei of the liver (a highly metabolizing organ involved in multiple regulatory functions) and the brown adipose tissue (responsible for nonshivering thermogenesis) from euthermic, hibernating, and arousing hazel dormice (Muscardinus avellanarius). Our observations demonstrate that, during hibernation, transcriptional activity significantly decreases and pre-mRNA processing factors undergo an intranuclear redistribution moving to domains usually devoid of such molecules; moreover, in hepatocytes, there is a preferential accumulation of pre-mRNAs at the splicing stage, whereas, in brown adipocytes, pre-mRNAs are mainly stored at the cleavage stage. Upon arousal, the pre-mRNAs at the cleavage stage are immediately utilized, while the maturation of pre-mRNAs at the splicing stage seems to be restored before transcription had taken place. Our data suggest a programmed intranuclear reorganization of the RNA maturation machinery aimed at efficiently and rapidly restoring the pre-mRNA processing, and, consequently, the specific cellular activities upon arousal. Once again natural hibernation appears as a highly programmed hypometabolic state rather than a simple fall of metabolic and physiological functions. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc. [source] Parthenogenetic Induction of Canine Oocytes by Electrical Stimulation and Ca-EDTAREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2009SR Lee Contents In this study, we investigated parthenogenetic induction of canine oocytes by electrical stimulation following Ca-EDTA treatment. Oocyte maturation, parthenogenetic development, and cleavage rate in canine after various electrical stimulations (1.5, 1.8, 2.1 kV/cm) for 50 ,s with single DC pulse following 1 mM Ca-EDTA treatment were investigated. In oocyte activated electrically at the voltage of 1.5 kV/cm after 1 mM Ca-EDTA treatment, the rate of pronucleus and two-cell was 4.1% and 2.7%, respectively. Although electrical stimulation could parthenogenetically induce immature oocyte to cleavage stage, degeneration rate in all experimental groups was more than 60%. This means that electrical stimulation after Ca-EDTA treatment could cause canine oocytes to be degenerated. However, two-cell in canine oocyte by parthenogenesis was for the first time induced. Therefore, we suggested that electrical stimulation for canine oocytes could induce parthenogenetically early embryonic cleavage. This result can be used as a basic data for parthenogenesis study in canine. Also, to perform more developed embryonic development, further study to parthenogenesis in canine need to be developed. [source] Morphological Aspects of In Vivo Cleavage in Myocastor coypus (coypu)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2004A. E. Felipe Summary The objective of the present work was to characterize the in vivo cleavage stage of Myocastor coypus embryos. For this purpose a colpocytological follow-up and controlled mating of 18 females were performed. Specimens from the beginning of the first cleavage to the acquisition of a morula appearance were considered to be in cleavage stage. Embryos in cleavage were collected between days 3 and 6 post-coitus. Of the collected embryos, 80% presented an even number of blastomeres and the remaining 20% an odd number. Embryos from 3 to 7 cells were blastomere associations in a spherical disposition within the zona pellucida. Blastomeres were spherical or ovoid, presenting slight flattening in areas contacting with other blastomeres. Embryos of 8 and 9 cells were as a group of blastomeres slightly elongated, surrounded by a spherical zona pellucida. The percentage of peri-vitelline space occupied by the embryonic mass ranged from 74.1 to 95.8% for all the substages. The cleavage pattern, developed in the oviduct, was of a rotational holoblastic type and asynchronic. [source] Postplasmic/PEM RNAs: A class of localized maternal mRNAs with multiple roles in cell polarity and development in ascidian embryosDEVELOPMENTAL DYNAMICS, Issue 7 2007François Prodon Abstract Ascidian is a good model to understand the cellular and molecular mechanisms responsible for mRNA localization with the discovery of a large family of localized maternal mRNAs, called postplasmic/PEM RNAs, which includes more than 40 members in three different ascidian species (Halocynthia roretzi, Ciona intestinalis, and C. savignyi). Among these mRNAs, two types (Type I and Type II) have been identified and show two different localization patterns from fertilization to the eight-cell stage. At the eight-cell stage, both types concentrate to a macromolecular cortical structure called CAB (for Centrosome Attracting Body) in the posterior-vegetal B4.1 blastomeres. The CAB is responsible for unequal cleavages and the partitioning of postplasmic/PEM RNAs at the posterior pole of embryos during cleavage stages. It has also been suggested that the CAB region could contain putative germ granules. In this review, we discuss recent data obtained on the distribution of Type I postplasmic/PEM RNAs from oogenesis to late development, in relation to their localization and translational control. We have first regrouped localization patterns for Type I and Type II into a comparative diagram and included all important definitions in the field. We also have made an exhaustive classification of their embryonic expression profiles (Type I or Type II), and analyzed their functions after knockdown and/or overexpression experiments and the role of the 3,-untranslated region (3,UTR) controlling both their localization and translation. Finally, we propose a speculative model integrating recent data, and we also discuss the relationship between postplasmic/PEM RNAs, posterior specification, and germ cell formation in ascidians. Developmental Dynamics 236:1698,1715, 2007. © 2007 Wiley-Liss, Inc. [source] Combinatorial expression patterns of heparan sulfate sulfotransferases in zebrafish: II.DEVELOPMENTAL DYNAMICS, Issue 12 2006The 6- O -sulfotransferase family Abstract Heparan sulfate (HS) is an unbranched chain of repetitive disaccharides, which specifically binds ligands when attached to the cell surface or secreted extracellularly. HS chains contain sulfated domains termed the HS fine structure, which gives HS specific binding affinities for extracellular ligands. HS 6- O -sulfotransferases (6-OST) catalyze the transfer of sulfate groups to the 6- O position of glucosamine residues of HS. We report here the characterization and developmental expression analysis of the 6-OST gene family in the zebrafish. The zebrafish 6-OST gene family consists of four conserved vertebrate orthologues, including a gene duplication specific to zebrafish. We examined the mRNA expression patterns in several tissues/organs throughout early zebrafish development, including early cleavage stages, eyes, somites, brain, internal organ primordial, and pectoral fin development. Members of the 6-OST gene family have spatially and temporally distinct restricted expression, suggesting in vivo functional differences exist between members of this family. Developmental Dynamics 235:3432,3437, 2006. © 2006 Wiley-Liss, Inc. [source] Protection of DNA during early development: adaptations and evolutionary consequencesEVOLUTION AND DEVELOPMENT, Issue 1 2003David Epel SUMMARY The rapidly dividing cleavage stages of embryos do not have the typical responses to cell damage, such as induction of the heat shock response, use of mitotic checkpoints, or use of apoptosis to eliminate severely damaged cells. This could create problems with integrity of DNA, but the solution in these embryos appears to be a "be prepared" approach, in which specific adaptations are used to minimize DNA damage during cleavage and the use of apoptosis at the mid-blastula transition to remove any cells that were nevertheless damaged. It has been assumed that this approach has evolved because of the advantage of rapid production of a motile larvae. Alternatively, this particular approach may have the selective advantage of increasing mutation rate when there are greater environmental stresses. This could provide more variants on which selective pressures could act and thus accelerate evolution during environmentally stressful periods. [source] Embryonic development of the oligochaete Enchytraeus coronatus: An SEM and histological study of embryogenesis from one-cell stage to hatchingJOURNAL OF MORPHOLOGY, Issue 1 2004Annette Bergter Abstract We describe the embryonic development of the soil-living oligochaete Enchytraeus coronatus (Enchytraeidae, Oligochaeta, Annelida). Enchytraeus coronatus is a direct developer. It follows the typical spiral cleavage mode of development that is highly conserved among annelids and a large number of other lophotrochozoan taxa that are collectively named "Spiralia." Scanning electron microscopy (SEM) was combined with light microscopic analysis of wholemounted and sectioned embryos, differentially processed through histological stainings, to reconstruct and document cellular movements and organogenesis from early cleavage stages until hatching. With the help of these data we have established a scheme of morphologically defined stages in order to facilitate future studies on the molecular and histological level that will allow a detailed cross-species comparison among annelids and other phyla. J. Morphol. 261:26,42, 2004. © 2004 Wiley-Liss, Inc. [source] Early ontogeny and placentation of the grey short-tailed opossum, Monodelphis domestica (Didelphidae: Marsupialia): contribution to the reconstruction of the marsupial morphotypeJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2001Zeller This study provides new findings on the placenta of Monodelphis domestica and a reconstruction of the marsupial morphotype. To achieve this, early ontogeny and placentation of the grey short-tailed opossum, M. domestica, from 3 h after copulation until birth (day 15), were studied and compared with other mammals. Both the ultrastructure and histochemistry of egg membranes, foetal membranes, oviduct and uterus were examined. The results of this study provide the first detailed ultrastructural description of a trophoblastic syncytium in a marsupial. In addition, this is the first original documentation of an invasive trophectoderm and an inflammatory reaction at parturition in M. domestica. These findings were compared with literature data and included into the reconstruction of the marsupial morphotype. Based on marsupial phylogeny as proposed by Luckett (J. Mammal. Evol. 2, 255,283, 1994), characters that are consistent at least within didelphids and dasyurids were determined to be characters of the marsupial morphotype. These characters are a central yolk separated from the peripheral yolk-poor cytoplasm in the unfertilized oocyte, the presence of a zona pellucida, a mucoid coat and a shell coat, the absence of a corona radiata, oviductal mucoid secretion, no shell secretion distal to the isthmus of the oviduct, uterine shell secretion, a short tubal passage (1 day at maximum), the apposition of blastomeres to the zona pellucida prior to intercellular association, the absence of a morula stage, the polarity of the zygotic yolk, the localized segmentation of deutoplasm (yolk) during the first cleavage and subsequent extrusion of yolk vesicles during the first two cleavage stages. With regard to the marsupial morphotype, the non-polarized yolk distribution in the zygote [Hartman (J. Morphol. 27, 1,84, 1916); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] is a derived character of Didelphis virginiana. Didelphis virginiana [Hartman (J. Morphol. 27, 1,84, 1916); Hartman (J. Morphol. 32, 1,139, 1919); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] and Didelphis marsupialis (Hill, Q. J. Micr. Sci. 63, 91,139, 1918) share the synapomorphous reduction of deutoplasmolysis to a generalized extrusion of vesicles. The absence of separated yolk and consequently a cleavage without yolk extrusion (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996) are apomorphies of macropodids. This is possibly correlated with the association of blastomeres in early cleavage stages (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996). A yolk sac placenta and a vascularized allantochorion can be assumed for part of the ontogeny in the marsupial morphotype, irrespective of the formation of an allantoic placenta at near term stages. The character polarization of the mode of placentation and parturition needs further investigation. Frühe Ontogenie und Plazentation der grauen Hausspitzmausbeutelratte, Monodelphis domestica (Didelphidae: Marsupialia): Ein Beitrag zur Rekonstruktion des Grundplans der Marsupialia Die vorliegende Arbeit beschreibt die frühe Ontogenese und Plazentation von 3 Stunden nach der Kopulation bis zur Geburt der Beutelratte Monodelphis domestica. Es wird die Ultrastruktur und Histochemie der Eihäute, der Fetalmembranen, des Oviductes und des Uterus beschrieben. Erstmalig wird die Ultrastruktur eines trophoblastischen Syncytiums bei einem Beuteltier beschrieben. Weiterhin wird ein invasives Trophektoderm und eine Entzündungsreaktion zum Zeitpunkt der Geburt bei M. domestica festgestellt. Die Befunde dieser Studie und Literaturdaten werden verglichen und in eine Grundplanrekonstruktion integriert. Merkmale, die mindestens zwischen Vertretern der Didelphidae und Dasyuridae übereinstimmen, werden basierend auf dem phylogenetischen System der Marsupialia nach Luckett, J. Mammal. Evol. 2, 255,283, 1994, für den Grundplan der Marsupialia angenommen. Diese Merkmale sind zentral separierter Dotter und peripheres dotterarmes Zytoplasma in der unbefruchteten Eizelle, das Vorhandensein von Zona pellucida, Mucoidschicht und Schalenhaut, das Fehlen einer Corona radiata, die Mucoidsekretion durch den Oviduct, die Schalensekretion durch den Uterus und nicht distal der Isthmusregion des Oviductes, eine kurze Tubenwanderung (maximal einen Tag), die Anlagerung der Blastomeren an die Zona pellucida vor der interzellulären Verbindung, das Fehlen eines Morulastadiums, die Dotterpolarität in der Zygote, die lokale Dotterabtrennung bei der ersten Teilung und die anschließende Dotterextrusion während der ersten beiden Teilungen. In Bezug auf den Grundplan der Marsupialia ist die unpolare Dotterverteilung in der Zygote ein abgeleitetes Merkmal von Didelphis virginiana. Didelphis virginiana und Didelphis marsupialis teilen als Synapomorphie die Reduktion der Deutoplasmolyse auf eine generelle Vesikelextrusion. Das Fehlen separierten Dotters in der Oocyte und die resultierende Furchung ohne Dotterextrusion [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996] ist eine Apomorphie der Macropodidae. Hiermit hängt möglicherweise die frühe Zusammenlagerung der Blastomeren zusammen [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996]. Ein vaskularisiertes Allantochorion und eine Dottersackplazenta können für einen Teil der Ontogenese im Grundplan der Marsupialia angenommen werden. Ob das Allantochorion neben der Respiration auch dem Stoffaustausch diente ist unklar. Die Lesrichtung für den Modus der Plazentation und der Geburt bedarf weiterer Untersuchungen. [source] Precambrian animal life: Taphonomy of phosphatized metazoan embryos from southwest ChinaLETHAIA, Issue 2 2005DORNBOS STEPHEN Phosphatized fossils from the Neoproterozoic Doushantuo Formation have provided valuable insight into the early evolution of metazoans, but the preservation of these spectacular fossils is not yet fully understood. This research begins to address this issue by performing a detailed specimen-based taphonomic analysis of the Doushantuo Formation phosphatized metazoan embryos. A total of 206 embryos in 65 thin sections from the Weng'an Phosphorite Member of the Doushantuo Formation were examined and their levels of pre-phosphatization decay estimated. The data produced from this examination reveal a strong taphonomic bias toward earlier (2-cell and 4-cell) cleavage stages, which tend to be well-preserved, and away from later (8-cell and 16-cell) cleavage stages, which tend to exhibit evidence for slight to intense levels of organic decay. In addition, the natural abundances of these embryos tend to decrease with advancement in cleavage stage, and no evidence of more advanced (beyond 16-cell) cleavage stages or eventual adult forms were found in this study. One possible explanation for this taphonomic bias toward early cleavage stages is that later cleavage stages and adult forms were more physically delicate, allowing them to be more easily damaged during burial and reworking, allowing for more rapid decay. The spectacular preservation of these embryos was probably aided by their likely internal enrichment in phosphate-rich yolk, which would have caused their internal dissolved phosphate levels to reach critical levels with only miniscule organic decay, thereby hastening phosphatization. If internal sources of phosphate did indeed play a role in the phosphatization of these embryos, it may explain their prolific abundance in these rocks compared to other phosphatized fossils as well as indicating that metazoans lacking such internal phosphate sources were likely much more difficult to preserve. The phosphatic fossils of the Doushantuo Formation, therefore, provide an indispensable, yet restricted, window into Neoproterozoic life and metazoan origins. [source] Isolation and characterization of a novel Xenopus gene (xVAP019) encoding a DUF1208 domain containing proteinMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 12 2007Xu Zhi Ruan Abstract We have identified a novel Xenopus gene (xVAP019) encoding a DUF1208 domain containing protein. Using whole-mount in situ hybridization and RT-PCR, we found abundant xVAP019 maternal transcripts in the animal hemisphere during the cleavage stages and blastula stages. During gastrulation xVAP019 is differentially expressed with higher levels in the animal helf and the highest in marginal zone, then further expressed widely at neuronal stages with strongest signals in the prospective CNS regions and the epidermal ectoderm. Subsequently xVAP019 was expressed predominantly in the head, the eyes, the otic vesicle, branchial arches, spinal cord, notochord, somites, and tailbud. It is absent or very weak in the endoderm. Injecting a morpholino oligo complementary to xVAP019 mRNA or injecting a caped xVAP019 mRNA caused most of embryos to die during gastrulation and neurulation. Overexpression of xVAP019 mRNA also led to eye defect, shorten interocular distance, small body size and abnormal pigment formation in parts of the survival embryos. Similar effects were induced by injecting the xVAP019 human homologous gene FAM92A1. Our results suggest that xVAP019 is essential for the normal ectoderm and axis mesoderm differentiation and embryos survival. This investigation is for the first time in vivo study examining the role of this novel gene and reveals an important role of xVAP019 in embryonic development. Mol. Reprod. Dev. 74: 1505,1513, 2007. © 2007 Wiley-Liss, Inc. [source] Differential cellular compartmentalization of the nuclear receptor SpSHR2 splicing variants in early sea urchin embryosMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2001Aikaterini Kontrogianni-Konstantopoulos Abstract SpSHR2 is a member of the nuclear receptor superfamily, expressed in embryos, larvae, and adult tissues of sea urchin. During embryonic development, two receptor isoforms are produced via alternative splicing. One exhibits the typical structure of nuclear receptors (SpSHR2-full length), whereas the other is missing the entire LBD (SpSHR2-splice variant). DNA-constructs encoding these isoforms and two additional in vitro generated deletion mutants were engineered in an expression vector carrying the myc-tag. Expression of the tagged isoforms in S. purpuratus embryos showed that the exogenous SpSHR2 full-length protein displays a similar subcellular localization as the endogenous receptor. In early cleavage stages (4-cells), the full-length isoform is predominantly localized in the nucleus, whereas two cell divisions later (16-cells) protein accumulations are detected in both the nucleus and cytoplasm. To the contrary, the SpSHR2-splice variant is confined in the embryonic nuclei both at 4- and 16-cell stage embryos. Analysis of the intracellular distribution of two receptor mutants, one having a deletion within the DBD (,P) and the other a truncation of the C-terminal F-domain (,F), revealed that ,P is localized similarly to full-length receptor, whereas ,F is maintained in the nucleus, similar to the SpSHR2 splice variant. Investigation of the DNA binding and dimerization properties of the two SpSHR2 isoforms demonstrated that they recognize and bind to a DR1-element as monomers, whereas ,P does not bind DNA and ,F binds to DR1 poorly. These results suggest that the receptor's putative LBD is responsible for the differential subcellular localization of the two natural SpSHR2-isoforms in early development. Mol. Reprod. Dev. 60: 147,157, 2001. © 2001 Wiley-Liss, Inc. [source] Effects of Gonadotropins on In Vitro Maturation and of Electrical Stimulation on Parthenogenesis of Canine OocytesREPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2010BS Kim Contents The objective of this study was to determine the effects of gonadotropins on in vitro maturation (IVM) and electrical stimulation on the parthenogenesis of canine oocytes. In experiment I, cumulus oocyte complexes were collected from ovaries at a random phase of the oestrus cycle and cultured on maturation medium treated with hCG or eCG for 48 or 72 h. There were no significant differences in the effects on the metaphase II (MII) rate between the hCG and eCG treatment groups over 48 h (5.4% vs 5.5%). The MII rate in the co-treatment group of hCG and eCG for 48 h was higher than in each hormone treated group (15.5%, p < 0.05). In experiment 2, the parthenogenetic effect on oocyte development, at various electrical field strengths (1.0, 1.5, 2.0 kV/cm DC) for 60 or 80 ,s with a single DC pulse after IVM on the co-treatment of hCG and eCG, was examined. The rate of pronuclear formation (37.1%) in electrical activation at 1.5 kV/60 ,s without cytochalasin B (CB) was higher than that of oocytes activated in the other groups (p < 0.05). However, we did not observe the cleavage stages. Also, CB did not influence parthenogenesis of canine oocytes. The results showed that the pronucleus formation rate, indicative of the parthenogenesis start point, could be increased by electrical stimulation. Therefore, these results can provide important data for the parthenogenesis of canine oocytes and suggest the probability of parthenogenesis in canines. [source] | |||||||||||||