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Effects of vitrification of partially denuded bovine immature oocytes

Krzysztof Papis
Department of Experimental Embryology, Polish Academy of Sciences Institute of Genetics and Animal Breeding, Jastrzębiec, 05-552 Magdalenka, Poland
Abstract :
In spite of many trials on bovine oocyte cryopreservation, their efficiency remains unsatisfactory,
regardless of method used. Although a births of about 15 calves obtained after transfer of embryos
developed from frozen or vitrified oocytes were reported by now, a total efficiency of oocyte
cryopreservation, in terms of blastocyst rate obtained, reaches approximately a half of those
reported for fresh oocytes. The authors’ former research on mature bovine oocyte vitrification
showed a possibility of obtaining a very high oocyte survival rate and development of up to 29.6%
of blastocysts. In the present paper, reported and discussed are results of similar vitrification
procedure, but employed for germinal vesicle stage (GV) of bovine oocytes. Immature cumulus-
oocyte complexes (COCs) obtained from ovarian follicles were vortexed for short time to strip off a
portion of cumulus cells. Vitrification was performed using microdroplet method in VS14 solution,
after 12-15 min pre-equilibration and 30 or 45 s equilibration periods. Warming was accomplished
in warm dilution medium, without sucrose. After
in vitro
maturation and fertilization, presumptive
zygotes were cultured
in vitro
up to day 10. Depending on pre-equilibration parameters 5.3- 8.4%
blastocysts developed from vitrified oocytes, that is significantly less compared to blastocyst ratio
obtained from control, fresh oocytes (40.9%, P≤0.01, Fisher test). Although the ratio of blastocysts
obtained from vitrified GV oocytes presented in this paper does not differ from the best results
reported elsewhere, the autors suggest a need of further extensive research on bovine immature
oocyte vitrification to obtain replicable, satisfactory efficiency.
Keywords :
blastocyst /cattle / immature oocytes / pre-equilibration / vitrification

Date Deposited : 02 Apr 2015 09:34

Last Modified : 02 Apr 2015 09:34

Official URL:

Volume 31, Number 1, - 2013

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