Document Detail

Consequences of non-extrusion of the first polar body and control of the sequential segregation of homologues and chromatids in mammalian oocytes.
MedLine Citation:
PMID:  8530665     Owner:  NLM     Status:  MEDLINE    
Absence of polar body formation, or premature chromatin condensation (PCC) in human oocytes can cause infertility. We studied in-vitro maturing mouse oocytes in order to identify risk factors for such conditions, and for the precocious segregation of homologues or chromatids. Treatment with the actin-binding drug cytochalasin D (10 micrograms/ml) arrested oocytes in metaphase I. Upon exposure to Ca(2+)-ionophores, anaphase I was triggered in the absence of cytokinesis. Chiasmata resolved and homologues separated instantaneously. In some oocytes predivision of all chromatids occurred. Homologues or chromatids never separated even after exposure to Ca(2+)-ionophores when microtubules were depolymerized, although bivalents could eventually decondense. Thus, in meiosis I checkpoints exist which ensure that homologue separation only takes place when a metaphase I spindle is present but cytokinesis and anaphase progression can be uncoupled. Cycloheximide induced a sequential separation of homologues in oocytes with intact metaphase I spindle, resulting in metaphase II chromosomes and bivalents in individual cells as also found in some human oocytes of aged females. In oocytes which progressed to metaphase II but failed to extrude a first polar body, the two sets of chromosomes eventually aligned on a common spindle ('diploid' metaphase II). PCC of one set was never observed. Ageing in vitro of cytochalasin D-blocked metaphase I oocytes had no pronounced effect on chromosome segregation.
D Soewarto; H Schmiady; U Eichenlaub-Ritter
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Human reproduction (Oxford, England)     Volume:  10     ISSN:  0268-1161     ISO Abbreviation:  Hum. Reprod.     Publication Date:  1995 Sep 
Date Detail:
Created Date:  1996-02-01     Completed Date:  1996-02-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8701199     Medline TA:  Hum Reprod     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  2350-60     Citation Subset:  IM    
Universität Bielefeld, Fakultät Biologie, Gentechnologie/Mikrobiologie, Germany.
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MeSH Terms
Actins / ultrastructure
Calcium / metabolism
Chromatids / ultrastructure*
Chromatin / ultrastructure*
Cytochalasin D / pharmacology
Cytoskeleton / ultrastructure
Oocytes / drug effects,  metabolism,  ultrastructure*
Time Factors
Reg. No./Substance:
0/Actins; 0/Chromatin; 22144-77-0/Cytochalasin D; 7440-70-2/Calcium

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

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