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Cumulus-oocyte Complexes (cumulus-oocyte + complex)
Selected AbstractsFunctional Morphology of Equine Pre-ovulatory Cumulus-oocyte ComplexesANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005S. Kölle Knowledge of the functional morphology of equine cumulus-oocyte-complexes (COCs) shortly before ovulation is scarce. Therefore the aim of our studies was to characterize COCs matured in vivo by light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and immunohistochemistry (ICC). Pre-ovulatory COCs were obtained by ultrasound-guided transvaginal aspiration of pre-ovulatory follicles of 26 pony mares. The morphology of pre-ovulatory COCs was compared to that of immature COCs obtained by slicing of ovaries from the slaughterhouse. As shown by light microscopy and SEM, immature COCs possess numerous round, densely packed cumulus cells, which contact each other and possess merely single short processes. Contrary, in pre-ovulatory oocytes the cumulus cells are widely separated but send long cytoplasmic processes to the zona pellucida (ZP). All the cumulus cells are embedded in a huge amount of homogenous extracellular matrix. As shown by alcian blue staining and Periodic Acid Schiff Reaction (PAS) with and without amylase digestion, this matrix contains glycoproteins and acidic and sulphated glycosaminoglycans. In pre-ovulatory COCs both the oocyte and the cumulus cells produce glycosaminoglycans, whereas immature COCs are negative for alcian blue. Similarly, glycoproteins are synthesized in pre-ovulatory, but not in immature COCs. As shown by ICC, hyaluronic acid is one of the most abundant mucopolysaccharide in the pre-ovulatory COC. The high synthetic activity of the cumulus cells in the pre-ovulatory COC is confirmed by TEM showing densely packed endoplasmic reticulum (ER) and accumulation of glycogen in the cumulus cells. Our results imply that in the equine in vitro maturation of the oocyte is characterized by the cumulus cells synthesizing an extracellular matrix of glycoproteins and acidic and sulphated glycosaminoglycans. The extensive production of extracellular, water-binding matrix in the pre-ovulatory COC ensures mechanical protection and nutrition of the oocyte. [source] Molecular Reproduction & Development: Volume 76, Issue 3MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2009Article first published online: 19 JAN 200 Cumulus-oocyte complex from rhesus monkey. Labeling emphasizes the retention of connexin43 (blue) between the metaphase II oocyte and the cumulus cells. Cytoskeleton is counterstained for filamentous actin (green) and beta-tubulin (red). The miRNA processing pathway of this complex is reported in the article by Mtango et al. in this issue. Image courtesy of Professor Catherine A. VandeVoort (University of California, Davis). [source] Reduced oxygen concentration improves the developmental competence of mouse oocytes following in vitro maturationMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 7 2007Kimberly A. Preis Abstract Reduced atmospheric oxygen concentration is beneficial to embryo development; however, optimal oxygen concentration for oocyte maturation remains undetermined. Likewise, there is no consensus of appropriate medium supplementation during maturation. The objective of this study was to determine whether oxygen tension (20% or 5% O2) and epidermal growth factor (EGF) affect oocyte metabolism and subsequent embryo development. Cumulus-oocyte complexes (COCs) were collected from 28-day-old equine chorionic gonadotropin (eCG) primed or unprimed F1 (C57BL/6xCBA) mice. COCs were matured in defined medium in one of four groups: 20% O2, 20% O2,+,EGF, 5% O2, 5% O2,+,EGF. In vivo matured COCs were also collected for analysis. COCs from unprimed mice, matured in 5% O2,±,EGF or 20% O2,+,EGF had higher metabolic rates than COCs matured in 20% O2 (P,<,0.05). COCs from primed mice had higher metabolic rates when matured in the presence of EGF, regardless of oxygen tension (P,<,0.01). Oxygen uptake and mitochondrial membrane potential were higher for in vivo matured oocytes and oocytes matured under 5% O2 compared to oocytes matured under 20% O2 (P,<,0.05). Blastocyst formation was not different between maturation groups (primed or unprimed); however, embryo cell numbers were 20,45% significantly higher when COCs were matured at 5% O2 (P,<,0.05). Results suggest that oocytes matured in physiological concentrations of oxygen have improved development and metabolic activity, more closely resembling in vivo maturation. These findings have implications for oocyte maturation in both clinical and research laboratories. Mol. Reprod. Dev. 74: 893,903, 2007. © 2006 Wiley-Liss, Inc. [source] Alterations and reversibility in the chromatin, cytoskeleton and development of pig oocytes treated with roscovitineMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 4 2003Jyh-Cherng Ju Abstract Germinal vesicle (GV) breakdown in mammalian oocytes is regulated by the activation of maturation promoting factor (MPF). We investigated a specific cdc2 kinase inhibitor, roscovitine, to maintain pig oocytes in the GV stage. Cumulus-oocyte complexes (COCs) were aspirated from slaughterhouse ovaries and cultured for 44 hr in NCSU#23 medium containing different levels of roscovitine (0, 10, 20, 30, 40, 50 ,M in Experiment 1 and 0, 40, 60, 80, 100, 120 ,M in Experiment 2). The COCs were cultured for another 44 hr after removal of the chemical. Twenty oocytes in each group were fixed at 44 hr for immunocytochemical labeling of the cytoskeleton and the rest (,20/group) were fixed at the end of 88 hr after culture. Results showed that the inhibition of the oocyte in the GV stage was not effective when 10,50 ,M (Experiment 1) of roscovitine were used (19,34%). When oocytes were released from the inhibitor, similar proportions (70,83%) of oocytes were observed in the MII or advanced stages among treatments. However, when higher concentrations of roscovitine were used (Experiment 2), significantly greater inhibitory effect was observed at the levels of 80,120 ,M with 83,91% oocytes being blocked in the GV stage when compared to the control (9%) and the 40,60 ,M (27,43%) groups (P,<,0.05). Although 15,21% of the oocytes showed abnormal MII morphology with aberrant meiotic spindles and/or formation of cytoplasmic microtubules, a substantial number of oocytes resumed meiosis and reached MII stage at 44 hr after removal of this chemical. In Experiment 3, different concentrations of roscovitine (0, 20, 40, and 80 ,M) were tested to examine the length of intervals (0, 11, 22, 33, and 44 hr) for an effective inhibition. Results showed that the inhibitory effect was significantly more prominent at 22 hr than that at 33 and 44 hr after roscovitine treatment in all treatment groups (P,<,0.05). This study demonstrated that roscovitine-treated oocytes resumed meiosis after removal of the inhibitor. This could provide flexibility for studying porcine oocyte development and embryo cloning and may have application in other species. Mol. Reprod. Dev. 64: 482,491, 2003. © 2003 Wiley-Liss, Inc. [source] | ||||||||||