lyonizationn.
/ˌlʌɪənʌɪˈzeɪʃən/ Genetics.
A process occurring in the very early stages of development of female mammalian embryos, in which one of the two X chromosomes is randomly inactivated in each of the existing cells.
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the world > life > biology > biological processes > procreation or reproduction > embryo or fetus > [noun] > formation of > genetic development
polyembryony1906
lyonization1963
1963 Lancet 12 Oct. 769/1 Mary Lyon proposed her hypothesis..in 1961... A colloquium on chromosome anomalies and D.N.A., held in Oporto on Sept. 12–14, devoted a good part of its time to this subject... This ‘Lyonisation’ (a convenient word invented at the colloquium) occurs in man presumably about the 12th day.
1977 Lancet 13 Aug. 339/2 This first occurs early in the growth of the female embryo, when a random decision on which chromosome to inactivate is apparently taken by each of the small number of cells then present, setting a precedent which is thereafter faithfully followed in each cell line, a process known as lyonisation.
1987 C. A. Clarke Human Genetics & Med. (ed. 3) viii. 59 Lyonization..explains why 15% of carrier females of the haemophilia gene have a normal concentration of factor VIII.
This entry has not yet been fully updated (first published 1997; most recently modified version published online December 2020).
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n.1963