Document Detail

Ultrastructural characteristics of fresh and frozen-thawed ovine embryos using two cryoprotectants.
MedLine Citation:
PMID:  11967184     Owner:  NLM     Status:  MEDLINE    
Cryopreservation of sheep embryos with ethylene glycol as a protectant appears to be more effective than glycerol, particularly at the morula stage, as has been demonstrated on the basis of in vitro and in vivo development rates after thawing. In this study we compare the ultrastructure of fresh morulae, thawed morulae, and blastocysts cryopreserved with either ethylene glycol or glycerol at the electron microscopic level, to look for cellular damage that could be responsible for proven differences in embryo survival after transfer. Embryos cryopreserved with glycerol showed unequal degrees of conservation even among blastomeres within a single embryo. In morulae, inner blastomeres were completely damaged, whereas external ones appeared to be intact. Both morulae and blastocysts cryopreserved with ethylene glycol showed a higher uniformity in blastomere conservation than embryos with glycerol. The most remarkable features in this experimental group were the presence of desmosomes following tight junctions between blastomeres and the presence of many microvilli on the outer surface of external blastomeres. These characteristics are similar in fresh embryos of the control group. Our results show that ethylene glycol protects membrane and cytoplasmic structures of embryonic cells from cryoinjury much better than glycerol. In vivo survival of embryos confirmed the ultrastructural observations. A limited permeability of glycerol would explain the observed ultrastructural differences in blastomere integrity, which depends on blastomere location and the differences between morulae and blastocysts. We conclude that the low reproductive yield after cryopreservation using glycerol can be attributed to the lack of protection of inner cells.
M J Cocero; S Moreno Díaz de la Espina; B Aguilar
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biology of reproduction     Volume:  66     ISSN:  0006-3363     ISO Abbreviation:  Biol. Reprod.     Publication Date:  2002 May 
Date Detail:
Created Date:  2002-04-22     Completed Date:  2002-09-10     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0207224     Medline TA:  Biol Reprod     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1244-58     Citation Subset:  IM    
Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria A, Dpt. de Reproducción Animal y Conservación de Recursos Zoogenéticos, Carretera de Ca Coruña km 5.9, 28040 Madrid, Spain.
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MeSH Terms
Blastocyst / drug effects,  ultrastructure
Cryoprotective Agents / pharmacology*
Embryo Transfer
Embryo, Mammalian / drug effects,  ultrastructure*
Ethylene Glycol / pharmacology*
Fetal Viability / physiology
Glycerol / pharmacology*
Microscopy, Electron
Reg. No./Substance:
0/Cryoprotective Agents; 107-21-1/Ethylene Glycol; 56-81-5/Glycerol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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