Document Detail

Evidence for the involvement of a species-specific embryonic protease in zona escape of hamster blastocysts.
MedLine Citation:
PMID:  11044463     Owner:  NLM     Status:  MEDLINE    
The source and nature of zona lytic factors during zona escape of hamster blastocyts were investigated. When cultured in hamster embryo culture medium (HECM)-2h, all 8-cell embryos (n = 135) developed to zona escaped-blastocysts with complete zona lysis. In addition, 2-cell embryos, when co-cultured with zona escaping-blastocysts (at a ratio of 1:10), exhibited zona lysis. Various other embryos at the 1-8-cell stages also showed zona lysis when cultured with zona-escaping blastocysts. However, zonae from mice, rats, sheep and humans were resistant to lysis under these conditions. Pronase treatment resulted in rapid zona lysis in hamsters (7 +/- 1 s), whereas in other species zona lysis was much slower: mouse (662 +/- 27 s), rat (532 +/- 16 s), sheep (120 +/- 12 s) and human (104 +/- 8 s). When cysteine protease inhibitors (antipain, leupeptin, E-64 and p-hydromercuricbenzoate) were tested, they completely inhibited zona escape, while trypsin inhibitors (TLCK and SBTI) did not. Uterine zona lysin contribution in zona escape was discounted since: (i) uterine luminal flushing and endometrial extract from day 4 (the time of zona escape in vivo) pregnant females failed to lyse zonae and (ii) endogenous oocytes and transferred 2-cell embryos (to day 3 pseudopregnant recipients) were all zona-intact, while 71% of transferred blastocysts exhibited zona escape, following their recovery after 24 h. These observations suggest that a species-specific, embryonic proteolytic factor, with a cysteine protease-like activity, is involved in the zona escape of blastocysts in hamsters.
A Mishra; P B Seshagiri
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular human reproduction     Volume:  6     ISSN:  1360-9947     ISO Abbreviation:  Mol. Hum. Reprod.     Publication Date:  2000 Nov 
Date Detail:
Created Date:  2000-12-22     Completed Date:  2000-12-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9513710     Medline TA:  Mol Hum Reprod     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1005-12     Citation Subset:  IM    
Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore-560012, India.
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MeSH Terms
Blastocyst* / cytology,  drug effects
Catalase / pharmacology
Coculture Techniques / methods
Cysteine Proteinase Inhibitors / pharmacology
Endopeptidases / metabolism*
Mucoproteins / metabolism
Oocytes / metabolism
Rats, Wistar
Species Specificity
Superoxide Dismutase / pharmacology
Trypsin Inhibitors / pharmacology
Uterus / metabolism
Zona Pellucida / drug effects,  enzymology*
Reg. No./Substance:
0/Cysteine Proteinase Inhibitors; 0/Mucoproteins; 0/Trypsin Inhibitors; 0/lysin; EC; EC Dismutase; EC 3.4.-/Endopeptidases

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