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Mature Oocytes (mature + oocyte)
Selected AbstractsReproductive biology of female big-bellied seahorsesJOURNAL OF FISH BIOLOGY, Issue 3 2004C. W. Poortenaar In this study, ovarian morphology, reproductive condition and sex steroid levels were investigated in the big-bellied seahorse Hippocampus abdominalis, collected by snorkel and SCUBA diving in Wellington Harbour, New Zealand. Within the ovary, oocytes were contained between an outer muscular wall and an inner layer of luminal epithelium. Two germinal ridges ran along the entire length of the ovary. In cross-section, oocytes were arranged in sequential order of development beginning at the germinal ridges and ending at the mature edge. Ovarian lamellae were absent. Vitellogenic and advanced cortical alveoli oocytes were elongated in shape, whereas maturing oocytes were distinctively pear-shaped. Mature oocytes were large (2·6 , 4·4 mm in length) and aligned with the animal pole towards the muscular wall. Reproductively mature females were found throughout the year indicating a protracted reproductive season. The gonado-somatic index was significantly different between all ovarian stages, but the hepato-somatic index was not. Females with previtellogenic ovaries had significantly higher plasma concentrations of testosterone than females with vitellogenic or maturing ovaries. There was no significant difference in plasma concentrations of testosterone between females with vitellogenic or maturing ovaries, or in plasma concentrations of 17,-oestradiol between females in all ovarian stages. This study contributes to the knowledge on the reproductive biology of female syngnathids. [source] Increase in multidrug transport activity is associated with oocyte maturation in sea stars,DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 9 2006Troy A. Roepke In this study, we report on the presence of efflux transporter activity before oocyte maturation in sea stars and its upregulation after maturation. This activity is similar to the multidrug resistance (MDR) activity mediated by ATP binding cassette (ABC) efflux transporters. In sea star oocytes the efflux activity, as measured by exclusion of calcein-am, increased two-fold 3 h post-maturation. Experiments using specific and non-specific dyes and inhibitors demonstrated that the increase in transporter activity involves an ABCB protein, P-glycoprotein (P-gp), and an ABCC protein similar to the MDR-associated protein (MRP)-like transporters. Western blots using an antibody directed against mammalian P-gp recognized a 45 kDa protein in sea star oocytes that increased in abundance during maturation. An antibody directed against sea urchin ABCC proteins (MRP) recognized three proteins in immature oocytes and two in mature oocytes. Experiments using inhibitors suggest that translation and microtubule function are both required for post-maturation increases in transporter activity. Immunolabeling revealed translocation of stored ABCB proteins to the plasma cell membrane during maturation, and this translocation coincided with increased transport activity. These MDR transporters serve protective roles in oocytes and eggs, as demonstrated by sensitization of the oocytes to the maturation inhibitor, vinblastine, by MRP and PGP-specific transporter inhibitors. [source] Maternal-effect gene Ces5/Ooep/Moep19/Floped is essential for oocyte cytoplasmic lattice formation and embryonic development at the maternal-zygotic stage transitionGENES TO CELLS, Issue 8 2010Fumi Tashiro In a search for genes specifically expressed in mouse embryonic stem cells, we identified one we called Ces5. We found that it corresponded to the Ooep gene, which was recently reported to be expressed specifically in oocytes. Mouse Ces5/Ooep, also called Moep19 or Floped, encoded a 164-amino acid protein, which was detected in the cytoplasm of developing and mature oocytes and in embryos throughout the preimplantation period. To examine its function, we carried out targeted disruption of this gene. The Ces5/Ooep -null mice were grossly normal, but the females were infertile. Although the ovaries and ovulation appeared normal, the embryos from Ces5/Ooep -null females mated with wild-type males showed developmental arrest at the two- or four-cell stage. In addition, their first cleavage was considerably delayed and often asymmetrical. Thus, Ces5/Ooep is a maternal-effect gene. By electron microscopy, we found that the eggs from Ces5/Ooep -null females lacked oocyte cytoplasmic lattices (CPLs), which have long been predicted to function as a storage form for components that are maternally contributed to the early embryo. Further analysis showed that CES5/OOEP was directly associated with the CPLs. These results indicate that CES5/OOEP is an essential component of the CPLs and is required for embryonic development at the maternal-zygotic stage transition. [source] Morphology of skin incubation in Pipa carvalhoi (Anura: Pipidae)JOURNAL OF MORPHOLOGY, Issue 11 2009Hartmut Greven Abstract South American Pipidae show a unique reproductive mode, in which the fertilized eggs develop in temporarily formed brood chambers of the dorsal skin after eggs have been deposited on the back of the female. We studied the skin incubation of Pipa carvalhoi using light microscopy and scanning electron microscopy. The skin consists of a stratified epithelium with a one-layered stratum corneum, and the dermis. The dermis of the dorsal skin of nonreproductive and reproductive females lacks a distinct stratum compactum, which is typical for most anuran skins. The entire dermis shows irregularly arranged collagen bundles like a stratum spongiosum. Before egg laying, the skin swells, primarily by thickening and further by loosening of the middle zone of the dermis. In the epidermis, large furrows develop that are the prospective sites of egg nidation. The epidermis, which forms a brood chamber around the developing egg becomes bi-layered and very thin and lacks a stratum corneum. Further, the dermis loosens and becomes heavily vascularized. Egg carrying females do not have mature oocytes in their ovaries indicating a slow down or interruption of egg maturation during this period. Similarities with the brood pouch of marsupial frogs are discussed. J. Morphol., 2009. © 2009 Wiley-Liss, Inc. [source] How does polyspermy happen in mammalian oocytes?MICROSCOPY RESEARCH AND TECHNIQUE, Issue 4 2003Wei-Hua Wang Abstract Polyspermy is one of the most commonly observed abnormal types of fertilization in mammalian oocytes. In vitro fertilization (IVF) provides approaches to study the mechanisms by which oocytes block polyspermic fertilization. Accumulated data indicate that oocyte, sperm and insemination conditions are all related to the occurrence of polyspermic fertilization. A high proportion of immature and aged oocytes showed polyspermy as compared with mature oocytes. Preincubation of oocytes and/or sperm with oviductal epithelial cells or collected oviductal fluid before IVF reduces polyspermic penetration. Recently, it was found that an abnormal zona pellucida is one of main causes of polyspermy in human eggs. A high proportion of polyspermy has resulted from the use of a high concentration of capacitated spermatozoa at the site of fertilization, irrespective of in the in vivo or in vitro environment. Oviductal secretions or oviductal epithelial cells themselves can regulate the number of spermatozoa reaching or binding to the zona pellucida thus reducing multiple sperm penetration. Suboptimal in vitro conditions, such as supplementations in IVF media, pH, and temperature during IVF, also induce polyspermic fertilization in some mammals. Species-specific differences are present regarding the relationship between insemination conditions and polyspermy. Microsc. Res. Tech. 61:335,341, 2003. © 2003 Wiley-Liss, Inc. [source] Dynamics of lamin A/C in porcine embryos produced by nuclear transferMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 9 2007Kiho Lee Abstract This study was conducted to investigate the presence of lamin A/C in porcine nuclear transfer embryos and to determine whether lamin A/C can serve as a potential marker for nuclear reprogramming. First, lamin A/C was studied in oocytes and embryos produced by fertilization or parthenogenetic oocyte activation. We found that lamin A/C was present in the nuclear lamina of oocytes at the germinal vesicle stage while it was absent in mature oocytes. Lamin A/C was detected throughout preimplantation development in both in vivo-derived and parthenogenetic embryos. Incubation of the activated oocytes in the presence of ,-amanitin (an inhibitor of RNA polymerase II), or cycloheximide (a protein synthesis inhibitor) did not perturb lamin A/C assembly, indicating that the assembly resulted from solubilized lamins dispersed in the cytoplasm. In nuclear transfer embryos, the lamin A/C signal that had previously been identified in fibroblast nuclei disappeared soon after fusion. It became detectable again after the formation of the pronucleus-like structure, and all nuclear transfer embryos displayed lamin A/C staining during early development. Olfactory bulb progenitor cells lacked lamin A/C; however, when such cells were fused with enucleated oocytes, the newly formed nuclear envelopes stained positive for lamin A/C. These findings suggest that recipient oocytes remodel the donor nuclei using type A lamins dispersed in the ooplasm. The results also indicate that lamin A/C is present in the nuclear envelope of pig oocytes and early embryos and unlike in some other species, its presence after nuclear transfer is not an indicator of erroneous reprogramming. Mol. Reprod. Dev. 74: 1221,1227, 2007. © 2007 Wiley-Liss, Inc. [source] Impact of in vitro production techniques on the expression of X-linked genes in bovine (bos taurus) oocytes and pre-attachment embryosMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2007Maria I. Nino-Soto Abstract Our previous studies showed that expression patterns of X-linked genes in cultured cells are different from those of their tissues of origin. This investigation analyses the transcription pattern of the X-linked genes BIRC4, GAB3, MECP2, RPS4X, SLC25A6, and XIST in bovine in vitro matured oocytes and in vitro fertilized embryos, and their in vivo counterparts. In vitro-derived pools of mature oocytes and pre-attachment embryos were obtained by: (a) TCM-199/serum with bovine oviductal epithelial cells as co-culture, and (b) synthetic oviductal fluid/BSA. Pools of in vivo-derived morulae and blastocysts were provided by a commercial embryo transfer operation. Total RNA was extracted for quantification of gene-specific transcript levels using real-time quantitative PCR. Statistical analysis was performed using a mixed model factorial ANOVA with ,,=,0.05. The effect of the in vitro environmental conditions on X-linked gene transcription was most evident during the fourth cell cycle, at the period of activation of the embryonic genome, and seemed to be less pronounced at later developmental stages, with the exception of BIRC4. The levels of X-linked genes transcripts in in vivo-derived embryos were lower relative to their in vitro counterparts for all genes tested. Finally, the pattern of expression of XIST in bovine oocytes and embryos was similar to that reported in humans. These results highlight the possibility that X-linked gene expression analysis is a useful tool to monitor the impact of reproductive biotechnologies on the developmental potential of embryos and aid in their improvement. Mol. Reprod. Dev. © 2006 Wiley-Liss, Inc. [source] Maternal chromatin remodeling during maturation and after fertilization in mouse oocytesMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2004Marcella Spinaci Abstract Immunofluorescence staining with antibodies against acetylated histone H4 and 5-methylcytosine was carried out to investigate female chromatin remodeling throughout oocyte maturation and chromatin rearrangement involving both male and female genomes after fertilization. Oocyte cytoplasm remodels female chromatin in preparation of the fertilizing event and the subsequent chromatin rearrangement. Histone H4 are in fact progressively deacetylated whereas demethylating enzymes do not seem to be active over this period. The acetylase/deacetylase balance seems to be cell cycle dependent as female chromatin is deacetylated during maturation and reacetylated at telophase II stage both after fertilization and activation. On the contrary, DNA demethylation seems to be strictly selective. It is in fact confined to the remodeling of paternal genome after fertilization of mature oocytes as the ooplasm is not effective in demethylating either paternal chromatin in germinal vesicle breakdown (GVBD) fertilized oocytes or maternal genome of partenogenetically activated oocytes. Surprisingly, we induced maternal chromatin demethylation after fertilization by treating oocytes with a combination of a methyltransferase inhibitor, 5-azacytidine (5-AzaC), and a reversible and specific inhibitor of histone deacetylase, trichostatin A (TSA). This treatment likely induces a hyperacetylation of histones (thus favoring the access to demethylating enzymes by opening female chromatin structure) associated with a block of reparative methylation by inhibiting methytransferases. This manipulation of chromatin remodeling may have applications regarding the biological significance of aberrant DNA methylation. Mol. Reprod. Dev. 69: 215,221, 2004. © 2004 Wiley-Liss, Inc. [source] In Vitro Production of Equine Embryos: State of the ArtREPRODUCTION IN DOMESTIC ANIMALS, Issue 2010K Hinrichs Contents In vitro embryo production is possible in the horse both clinically and for research applications. Oocytes may be collected from excised ovaries post-mortem, or from either immature follicles or stimulated pre-ovulatory follicles in the live mare. In vitro maturation of immature oocytes typically yields approximately 60% mature oocytes. As standard in vitro fertilization is not yet repeatable in the horse, fertilization is performed by intracytoplasmic sperm injection. Embryo culture requires medium with high glucose, at least during blastocyst development, and rates of blastocyst development similar to those for cattle (25% to 35%) may be obtained. Pregnancy rates after transfer of in vitro -produced blastocysts are similar to those for embryos recovered ex vivo. [source] Mitochondrial Activity, Distribution and Segregation in Bovine Oocytes and in Embryos Produced in VitroREPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2006AM Tarazona Contents Bovine oocytes and embryos produced in vitro were studied to determine the mitochondrial pattern of distribution, segregation and activity using DIOC 6 and Jc-1 fluorescence. The highest fluorescence level observed in mature oocytes was taken as 100% activity and six activity levels were estimated as follows: (1) 0%, (2) 1,15%, (3) 16,30%, (4) 31,50%, (5) 51,75% and (6) 76,100%. Three patterns of mitochondrial distribution were found: (1) diffused throughout the cytoplasm in oocytes and embryos, (2) pericytoplasmic in oocytes and embryos, and (3) perinuclear only in embryos. The segregation of mitochondria in blastomeres showed two distinct patterns: (1) symmetrical with an even mitochondrial population, and (2) asymmetrical with different numbers of mitochondria in each blastomere. In immature oocytes, mitochondrial activity was very low and the distribution was diffuse or negligible, while in mature oocytes the activity was high and the distribution was diffuse or pericytoplasmic. Competent embryos up to the 16-cell stage showed intermediate levels of activity (16,50%) but activity decreased thereafter up to the blastocyst stage. Non-competent embryos showed low levels of activity (1,15%) at all stages. These results suggest that mitochondria might play an important role during early development and that a minimum threshold of activity regulates the potential competence for reaching the blastocyst stage. [source] Genetic characterization and gonad development of artificially produced interspecific hybrids of the abalones, Haliotis discus discus Reeve, Haliotis gigantea Gmelin and Haliotis madaka HabeAQUACULTURE RESEARCH, Issue 5 2008Faruq Ahmed Abstract Hybridization among abalone species has been suggested as a possible means to increase their growth rates for aquaculture. As a first step to test the usefulness of the hybrids of Japanese abalone species (Haliotis discus discus, Haliotis gigantea and Haliotis madaka) for aquaculture, we characterized the genetic background and gonad development of hybrids that were produced by artificial insemination. The hybrid status of the resulting offspring was confirmed by assaying 14 allozymes and by RFLP analysis of the 16s rRNA and cytochrome oxidase I (COI) regions of mtDNA using 13 restriction enzymes. Histological examination of the gonads of the hybrids was conducted in comparison with those of the parental species. Cross-breeding among the three species was conducted successfully in all combinations although with lower fertilization rates (means of 1.3,60.8%) than the parental species (34.3,90%). Crosses between H. discus discus and H. madaka had higher fertilization rates (22.4,60.8%) than those involving H. gigantea (1.3,19.9%). The hybrids were ascertained by the presence of both parental genotypes at the LDH-A, ME-A, MDH-A and GPI loci. The maternal origin of the hybrid mtDNA was confirmed by digestion with DdeI, TaqI, HpaII of the COI region. No polymorphism was observed in the 16S rRNA region. The hybrids had gonadal development and maturity stages similar to the parental species up to fully mature oocytes and sperm. They spawned upon stimulation and produced viable offspring with high fertilization rates and successful development to the juvenile stage in back- and homologous hybrid crosses. [source] | ||||||||||||||||