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In vivo ovulation, oocyte maturation and fertilisation in the bitch

Alain Fontbonne
Abstract : Timing the day of ovulation as accurately as possible is considered by most authors as one of the most important factor in order to determine when to inseminate bitches. This is especially important when using frozen semen, due to the relatively short survival of frozen/thawed semen in the female genital tract after artificial insemination. In our study, we first tried to find the most accurate technique to determine the exact occurrence of ovulation in the bitch. We hypothesized that ovarian ultrasound examination could be a reliable and accurate method to determinate ovulation in bitches. Our aims were to try to detect ovulation by ultrasound in different breeds and to evaluate the interests and the accuracy of such a technique, compared with hormonal levels around ovulation. Our study confirmed that ovarian ultrasound was an accurate technique for timing ovulation in the bitch. We also found that, although more accurate, ovarian ultrasound examinations improved the accuracy of ovulation detection in only 15.3 % of bitches compared with progesterone. Altogether, progesterone plasma concentrations appeared fairly constant around ovulation, whatever the breed, and, as a whole, progesterone assays appeared as a precise method to time ovulation. Using ovarian ultrasound examinations as the reference technique to time ovulation in the bitch, we then aimed to evaluate the precise kinetics of in vivo oocyte maturation in the bitch, as well as early embryonic development. Furthermore, we wanted to check if, in vivo, spermatozoa were able to penetrate oocytes still at immature stages. We found that the germinal vesicle (GV) stage was the only one present until 44 hours after ovulation. The first metaphase II stage was observed at 54 hours. Various oocyte maturation stages were observed at the same time within each bitch. Fertilisation occurred in most cases from 90 hours post-ovulation in mature oocytes (metaphase II). In vivo penetration of immature oocytes by spermatozoa was extremely rare. These fundamental results may lead to an improvement or a simplification in everyday veterinary practice, especially for artificial insemination with frozen-thawed semen. Furthermore, a better knowledge of the processes involved in in vivo oocyte maturation, fertilisation and early embryonic development are important steps towards the improvement of reproductive biotechnologies in the canine species.
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Contributor : Ecole Agroparistech <>
Submitted on : Thursday, December 4, 2008 - 8:00:00 AM
Last modification on : Thursday, December 4, 2008 - 8:00:00 AM
Long-term archiving on: : Thursday, September 30, 2010 - 8:41:23 PM

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Alain Fontbonne. In vivo ovulation, oocyte maturation and fertilisation in the bitch. Life Sciences [q-bio]. AgroParisTech, 2008. English. ⟨NNT : 2008AGPT0010⟩. ⟨pastel-00004418⟩

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