Effects of cooling and rewarming on the meiotic spindle and chromosomes of in vitro-matured bovine oocytes
Rebecca R. Aman,John E. Parks +1 more
TLDR
Spindles did not return to normal in most oocytes regardless of cooling temperature or rewarming scheme, and step-wise rewarming was no more beneficial than direct rewarming.Abstract:
The purpose of this study was to evaluate effects of cooling and rewarming on the meiotic spindle apparatus of bovine oocytes In experiment 1, in vitro-matured bovine oocytes were either maintained at 39 degrees C or cooled abruptly to 4 degrees C or approximately 25 degrees C Immunohistochemical and DNA staining for visualization of microtubules and chromosomes, respectively, revealed an anastral, barrel-shaped spindle in bovine oocytes Exposure to 4 degrees C for 10-20 min caused complete disappearance of the spindle Some chromosome dispersion occurred after 60 min at 4 degrees C After exposure to approximately 25 degrees C for 30 min, 90% of oocytes appeared abnormal, having either an abnormal spindle or no spindle In experiment 2, oocytes cooled to either approximately 25 degrees C or 4 degrees C for 30 min were rewarmed directly or in steps for 15 or 60 min Spindles did not return to normal in most oocytes regardless of cooling temperature or rewarming scheme Step-wise rewarming was no more beneficial than direct rewarming More of the oocytes rewarmed directly contained dispersed chromosomes as time at 39 degrees C increasedread more
Citations
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Development into blastocysts of bovine oocytes cryopreserved by ultra-rapid cooling.
TL;DR: To "outrace" chilling injury, oocytes contained in < 1 microliter of EG solution were placed onto electron microscope grids and plunged directly into N2 slush or LN2, and 30% of them cleaved after IVF, and half of these developed into blastocysts-- survival rates equivalent to those for oocytes that had been exposed to EG without any cooling.
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Production, freezing and transfer of bovine IVF embryos and subsequent calving results
J.F. Hasler,W.B. Henderson,P.J. Hurtgen,Z.Q. Jin,A.D. McCauley,S.A. Mower,B. Neely,L.S. Shuey,J.E. Stokes,S.A. Trimmer +9 more
TL;DR: Although there was no difference in pregnancy rate, embryos resulting from co-culture with Buffalo Rat Liver Cells n Menezo's B2 medium developed faster than embryos co-cultured with TCM 199 culture medium.
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Are programmable freezers still needed in the embryo laboratory? Review on vitrification
Gábor Vajta,Zsolt Peter Nagy +1 more
TL;DR: The opinion of the authors is that vitrification is the future of cryopreservation and that lack of support from regulatory authorities, and conservative approachs regarding novel techniques can slow down the implementation of vitrification.
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High developmental rates of vitrified bovine oocytes following parthenogenetic activation, in vitro fertilization, and somatic cell nuclear transfer.
TL;DR: An effective vitrification protocol to cryopreserve bovine oocytes for research and practice of parthenogenetic activation, in vitro fertilization, and nuclear transfer was developed.
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Cryoprotectant Toxicity: Facts, Issues, and Questions
TL;DR: This review attempts to describe what is known about CPA toxicity, theories of CPA Toxicology, and strategies to reduce CPAoxicity.
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Pregnancy after human oocyte cryopreservation
TL;DR: The first successful attempt at deep freezing and thawing of the human oocyte is reported and a twin pregnancy was achieved after insemination and replacement in utero.
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Transient cooling to room temperature can cause irreversible disruption of the meiotic spindle in the human oocyte
TL;DR: The effect of cooling to room temperature for either 10 or 30minutes on the microtubule system of oocytes has been investigated in this article, showing that the spindles in oocytes that were cooled for either one or four hours were found to resemble those in non-cooled control oocytes in less than one half of the cases examined.
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Fertilization in vitro and development to term of unfertilized mouse oocytes previously stored at --196 degrees C
TL;DR: Much higher rates of survival to 14-day fetuses and live-born were found after the fertilization of frozen-thawed oocytes in vitro and subsequent transfer at the 2-cell or blastocyst stage to pseudopregnant recipients.
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TL;DR: Analysis of ovarian cryosections stained with the DNA‐binding fluorochrome Hoechst 33258 indicates that sequential changes in GV chromatin occur duing folliculogenesis that result in the formation of a continuous perinucleolar chromatin sheath at the time of antrum formation.