Chromatin Patterns of Immature Canine Oocytes after In Vitro Maturation
Article first published online: 24 DEC 2012
© 2012 Blackwell Verlag GmbH
Reproduction in Domestic Animals
Special Issue: Canine and Feline Reproduction VII: Reproductive Biology and Medicine of Domestic and Exotic Carnivores. Proceedings of the 7th Quadrennial International Symposium on Canine and Feline Reproduction. Whistler, Canada. 26-29 July 2012.
Volume 47, Issue Supplement s6, pages 70–73, December 2012
How to Cite
Reynaud, K., Chebrout, M., Tanguy-Dezaux, C., de la Villéon, G. and Chastant-Maillard, S. (2012), Chromatin Patterns of Immature Canine Oocytes after In Vitro Maturation. Reproduction in Domestic Animals, 47: 70–73. doi: 10.1111/rda.12054
- Issue published online: 24 DEC 2012
- Article first published online: 24 DEC 2012
- Manuscript Accepted: 13 JUL 2012
- Manuscript Received: 27 JUN 2012
In canine species, in vitro maturation (IVM) rates of oocytes collected from anoestrous ovaries are low (<20%). Several IVM media have been tested without significant improvements. A critical step in the evaluation of culture conditions is the observation of the meiotic stage reached by the oocytes. The present study was designed to investigate the chromatin patterns of in vitro matured oocytes by visualizing Germinal Vesicle (GV) and Germinal Vesicle Breakdown (GVBD) structures at 72 h of IVM. Nuclear stages of 1678 oocytes were evaluated by confocal microscopy after IVM. 1204 oocytes were non-degenerated, and 94.4% were still immature and at GV stage. Five different patterns of chromatin configuration were observed. Higher percentages of oocytes with unmodified GV and with diffuse (58%; Type A) and filamentous chromatin (19%; Type B) were observed in comparison with those with modifications in the GV such as patched chromatin (12.5%; Type C), surrounded-nucleolus (3%; Type D) and in vivo type chromatin/fully grouped chromatin (2.5%; Type E). These results indicate that GVBD (absence of nucleolus, nucleus breakdown) is rarely observed in vitro. The percentage of type C-D-E GVs and MI (meiotic resumption) and of MII (completion of meiosis) can be used to evaluate meiotic resumption after IVM. Our results indicate that although a low number of in vitro matured oocytes exhibit the chromatin configurations observed in in vivo collected oocytes, chromatin changes in the GV can be induced during IVM.