Document Detail

In vitro maturation and transmission electron microscopic observation of horse oocytes after vitrification.
MedLine Citation:
PMID:  8689887     Owner:  NLM     Status:  MEDLINE    
The study was designed to examine the suitability of immature horse oocytes for vitrification. Immature oocytes derived from slaughtered horse ovaries were transferred to a vitrification solution (EFS; 40% ethylene glycol, 18% Ficoll, and 0.3 M sucrose in modified phosphate-buffered saline) directly (Groups 1 and 4) or were first exposed to 20% ethylene glycol solution for 10 min (Groups 2 and 5) or 20 min (Groups 3 and 6). Oocytes were handled at 20 degrees C (Groups 1, 2, and 3) or 30 degrees C (Groups 4, 5, and 6). After vitrification and warming, their viability was assessed by maturation culture for 32 h. The percentages of oocytes reaching the metaphase II stage after the in vitro maturation in Groups 2, 3, 5, and 6 (16.0, 16.7, 10.0. and 8.2%, respectively) were higher than those in Groups 1 and 4 (2.2 and 1.9%, respectively). In untreated control oocytes, 55.6% completed meiosis in vitro. Transmission electron microscopy was used to compare the fine structure of vitrified oocytes (treated as Group 2) with those of untreated control oocytes and EFS-exposed, nonvitrified oocytes (n = 10 each). The viability of EFS-exposed oocytes, assessed by in vitro maturation, was 27.7%. Vitrification induced some ultrastructural changes, such as the swelling of mitochondria together with reduced matrix density, the destruction of communication between oocytes and their surrounding cumulus cells, and the presence of vacuoles located in the periphery of the ooplasm. However, these changes were not always observed. Exposure of the oocytes to EFS solution induced similar ultrastructural changes in mitochondria and cell-cell communication but to a lesser extent. However, the exposure to EFS induced vacuoles in the periphery of the ooplasm to the same extent as did the vitrification. Thus, immature horse oocytes can be cryopreserved by vitrification with EFS solution. Reduced viability of EFS-exposed and/or vitrified horse oocytes may relate to morphological changes such as destruction of the intercellular communications between cumulus cells and oocytes.
S Hochi; M Kozawa; T Fujimoto; E Hondo; J Yamada; N Oguri
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cryobiology     Volume:  33     ISSN:  0011-2240     ISO Abbreviation:  Cryobiology     Publication Date:  1996 Jun 
Date Detail:
Created Date:  1996-08-26     Completed Date:  1996-08-26     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0006252     Medline TA:  Cryobiology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  300-10     Citation Subset:  IM    
Laboratory of Horse Production, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
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MeSH Terms
Cell Survival
Cryopreservation / methods*
Cryoprotective Agents
Ethylene Glycol
Ethylene Glycols
Evaluation Studies as Topic
Microscopy, Electron
Oocytes* / growth & development,  ultrastructure
Time Factors
Reg. No./Substance:
0/Cryoprotective Agents; 0/Ethylene Glycols; 107-21-1/Ethylene Glycol; 25702-74-3/Ficoll; 57-50-1/Sucrose

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