Document Detail

Meiotic configurations in female trisomy 21 foetuses.
MedLine Citation:
PMID:  6232197     Owner:  NLM     Status:  MEDLINE    
Analysis of the meiotic configurations formed by the three No 21 chromosomes in oocytes from two trisomy 21 foetuses was undertaken using a spreading technique. Light microscope analysis of the first gave limited resolving power, such that over half the oocytes could not be classified as to presence or absence of trivalent or bivalent plus univalent. In the second, investigated at the electron microscope level, all 65 cells analysed were informative and precise detail of meiotic pairing in trivalents could be obtained. Two principal forms of trivalent occurred, one in which pairing was initiated at opposite ends of the three No 21's, each initiation point involving only two of the three homologous lateral elements; the other in which pairing was initiated by all three elements at the same end, a triple synaptonemal complex being formed. Only in one oocyte out of the 65 analysed at EM level, however, did triple pairing occur along the entire length of the No 21 trivalent. All others showed splitting into bivalent and univalent at some point along the structure. Unpaired regions within trivalents and all univalents were consistently seen to be thickened and dark staining with silver over the whole period from pachytene to diplotene. This contrasted with the desynapsing lateral elements of previously paired synaptonemal complexes which appeared thin by comparison at diplotene. The significance of the thickening remains, as yet, obscure.
R M Speed
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Human genetics     Volume:  66     ISSN:  0340-6717     ISO Abbreviation:  Hum. Genet.     Publication Date:  1984  
Date Detail:
Created Date:  1984-05-30     Completed Date:  1984-05-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7613873     Medline TA:  Hum Genet     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  176-80     Citation Subset:  IM    
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MeSH Terms
Chromosomes, Human, 21-22 and Y / ultrastructure*
Down Syndrome / genetics*
Microscopy, Electron
Oocytes / cytology*,  ultrastructure

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