Predivision in human oocytes at meiosis I: a mechanism for trisomy formation in man

Cytogenetic preparations from oocytes remaining unfertilised after in vitro fertilisation revealed single chromatids (as opposed to whole chromosomes) in 4 out of 38 meiosis II metaphases. In one oocyte, a single chromatid was present in addition to the normal 23,X complement, and in three oocytes,...

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Bibliographic Details
Published inHuman genetics Vol. 86; no. 4; p. 383
Main Author Angell, R R
Format Journal Article
LanguageEnglish
Published Germany 01.02.1991
Subjects
Anaphase
Chromatids - ultrastructure
Female
Fertilization in Vitro
Haploidy
Humans
Karyotyping
Meiosis
Models, Genetic
Oocytes - cytology
Trisomy
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Summary:Cytogenetic preparations from oocytes remaining unfertilised after in vitro fertilisation revealed single chromatids (as opposed to whole chromosomes) in 4 out of 38 meiosis II metaphases. In one oocyte, a single chromatid was present in addition to the normal 23,X complement, and in three oocytes, two identical but separate chromatids replaced one whole chromosome within the complement. The data indicate that the chromatids have arisen as a result of premature division of the centromeres at meiosis I ("predivision"). None of the oocytes were hyperhaploid with an extra whole chromosome. These findings are at variance with the general belief that trisomy in man is largely a consequence of nondisjunction of whole bivalents at meiosis I and they suggest that predivision resulting in separate chromatids may be a significant mechanism for human trisomy.
ISSN:0340-6717
DOI:10.1007/bf00201839