%0 Journal Article
%T Structural Changes in Cattle Immature Oocytes Subjected to Slow Freezing and Vitrification
%A H. Wahid*
%A M. Thein1
%A E.A. El-Hafez2
%A M.O. Abas3
%A K. Mohd Azam4
%A O. Fauziah5
%A Y. Rosnina and H. Hajarian
%J Pakistan Veterinary Journal
%D 2012
%I University of Agriculture, Faisalabad
%X This study was conducted to evaluate the effect of different cryopreservation methods (slow-freezing and vitrification) on structural changes of bovine immature oocytes. Bovine ovaries were collected from local abattoirs. Cumulus-oocyte-complexes (COCs) were retrieved using aspiration method from 2-6 mm follicles. In Experiment 1, selected oocytes were randomly divided into 4 treatment groups namely freezing solution-exposed, frozen-thawed, vitrification solution-exposed and vitrified-thawed and then oocytes abnormalities were examined under a stereomicroscope. In Experiment 2, oocytes were randomly allocated to the same grouping as experiment 1 plus control group. Following freezing or vitrification, all oocytes were fixed in glutaraldehyde and processed for transmission electron microscopy. In experiment 1, there was a higher incidence of abnormalities in the frozen-thawed and vitrified-warmed oocytes compared to those in freezing solution and vitrification solution-exposed groups (P<0.05). In experiment 2, there were marked alterations in the perivitelline space, microvilli and vesicles of frozen-thawed and vitrified-warmed oocytes characterized by loss of elasticity and integrity of cytoplasmic processes and microvilli following cooling and warming. In conclusion, ethylene glycol-based freezing and vitrification solutions are suitable choices for cryopreservation of immature oocytes and most organelles are able to retain their normal morphology following cryopreservation and thawing processes.
%K Bovine
%K Cryopreservation
%K Oocyte
%K Ultrastructure
%K Vitrification
%U http://pvj.com.pk/pdf-files/32_2/188-192.pdf