Are Oocytes from the Anestrous Bitch Competent for Meiosis?

Authors

  • S Chastant-Maillard,

    1. INRA, UMR 1198 Biologie du Développement et Reproduction, Domaine de Vilvert, Jouy-en-Josas, France
    2. ENVA, UMR1198, Maisons-Alfort, France
    Current affiliation:
    1. INP-ENVT, Reproduction, Toulouse, France
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    • SCM and MSD contributed equally to this work.

  • M Saint-Dizier,

    Corresponding author
    1. ENVA, UMR1198, Maisons-Alfort, France
    2. AgroParisTech, UFR Génétique Elevage Reproduction, Paris Cedex 05, France
    • INRA, UMR 1198 Biologie du Développement et Reproduction, Domaine de Vilvert, Jouy-en-Josas, France
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    • SCM and MSD contributed equally to this work.

  • B Grimard,

    1. INRA, UMR 1198 Biologie du Développement et Reproduction, Domaine de Vilvert, Jouy-en-Josas, France
    2. ENVA, UMR1198, Maisons-Alfort, France
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  • M Chebrout,

    1. INRA, UMR 1198 Biologie du Développement et Reproduction, Domaine de Vilvert, Jouy-en-Josas, France
    2. ENVA, UMR1198, Maisons-Alfort, France
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  • S Thoumire,

    1. INRA, UMR 1198 Biologie du Développement et Reproduction, Domaine de Vilvert, Jouy-en-Josas, France
    2. ENVA, UMR1198, Maisons-Alfort, France
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  • K Reynaud

    1. INRA, UMR 1198 Biologie du Développement et Reproduction, Domaine de Vilvert, Jouy-en-Josas, France
    2. ENVA, UMR1198, Maisons-Alfort, France
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Author's address (for correspondence): M Saint-Dizier, AgroParisTech, 16 rue Claude Bernard, 75231 Paris Cedex 05, France. E-mail: stdizier@agroparistech.fr

Contents

In the bitch, oocyte meiosis resumption takes place in the oviduct. Using oocytes from anestrous bitches, in vitro maturation (IVM) generally gives very poor results. To investigate the contribution of oocyte competence to the low IVM yield, we compared in vivo maturation in an optimal environment with conventional IVM. A total of 418 grade 1 cumulus-oocyte complexes (COCs) from 10 anestrous bitches were transferred into the oviducts of recipient bitches either on Day −1 (n = 3 recipients), Day 0 (n = 2) or on Day +1 (n = 2) relative to ovulation. For each donor bitch, 20 grade 1 COCs were also cultured in vitro. After 72 h of in vivo or IVM, the nuclear stage of oocytes was determined after DNA and tubulin staining. Of the 154 oocytes recovered and examined after intratubal transfer, only 2% reached the metaphase I or II stage and 38.3% were degenerated. Oocytes cultured in vitro displayed a higher metaphase rate (7.6%, n = 170) and lower degeneration rate (12.9%) compared with transferred oocytes (p < 0.001). These results clearly demonstrate that the oocyte competence is the major limiting factor of IVM efficiency in the dog. Mimicking the tubal environment may thus not be sufficient to increase IVM yield in this species.

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