IVM of mouse fully grown germinal vesicle oocytes upon a feeder layer of selected cumulus cells enhances their developmental competence
Federica Cavalera A , Milena Simovic A B , Mario Zanoni A , Valeria Merico A , Silvia Garagna A C and Maurizio Zuccotti A CA Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia e Biotecnologie ‘Lazzaro Spallanzani’, University of Pavia, Via Ferrata, 9, 27100 Pavia, Italy.
B German Cancer Research Center, Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
C Corresponding authors. Email: silvia.garagna@unipv.it; maurizio.zuccotti@unipv.it
Reproduction, Fertility and Development 31(6) 1068-1077 https://doi.org/10.1071/RD18444
Submitted: 5 May 2018 Accepted: 9 January 2019 Published: 29 March 2019
Abstract
In the ovary, acquisition of oocyte developmental competence depends on a bidirectional exchange between the gamete and its companion cumulus cells (CCs). In this study we investigated the contribution of CCs surrounding oocytes of known developmental competence or incompetence to the acquisition of oocyte developmental competence. To this end, feeder layers of CCs (FL-CCs) were prepared using CCs isolated either from: (1) developmentally competent mouse oocytes whose nucleolus was surrounded by a chromatin ring (FL-SN-CCs); or (2) developmentally incompetent mouse oocytes whose nucleolus was not surrounded by a chromatin ring (FL-NSN-CCs). Denuded, fully grown oocytes (DOs) were matured to the MII stage on either FL-SN-CCs or FL-NSN-CCs, inseminated with spermatozoa and cultured throughout preimplantation development. FL-SN-CCs significantly improved the acquisition of oocyte developmental competence, with a blastocyst development rate equal to that for maturation of intact cumulus–oocyte–complexes. In contrast, DOs matured on FL-NSN-CCs or in the absence of CCs exhibited developmental failure, with embryos arresting at either the 4-cell or morula stage. These results set a culture platform to further improve the protocols for the maturation of DOs and to unravel the molecules involved in the cross-talk between the gamete and its companion CCs during the germinal vesicle to MII transition.
Additional keywords : culture, ovary, preimplantation.
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