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Are Oocytes from the Anestrous Bitch Competent for Meiosis?
Author(s) -
ChastantMaillard S,
SaintDizier M,
Grimard B,
Chebrout M,
Thoumire S,
Reynaud K
Publication year - 2012
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/rda.12007
Subject(s) - oocyte , meiosis , andrology , ovulation , in vitro maturation , oviduct , biology , metaphase , in vivo , embryo , endocrinology , genetics , medicine , chromosome , gene , hormone
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 ( COC s) from 10 anestrous bitches were transferred into the oviducts of recipient bitches either on D ay −1 (n = 3 recipients), D ay 0 (n = 2) or on D ay +1 (n = 2) relative to ovulation. For each donor bitch, 20 grade 1 COC s 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.