Angell R R, Xian J, Keith J, Ledger W, Baird D T
Department of Obstetrics and Gynaecology, University of Edinburgh, UK.
Cytogenet Cell Genet. 1994;65(3):194-202. doi: 10.1159/000133631.
Trisomy is the single most frequent type of chromosome abnormality in humans and has considerable impact on many aspects of human pathology. It arises most commonly through "nondisjunction" at maternal meiosis I, but the underlying mechanism of formation remains obscure. Analysis of 100 haploid oocytes at second meiotic metaphase shows that the only type of chromosome abnormality compatible with trisomy formation after fertilisation is the presence of single chromatids in addition to, or replacing, whole chromosomes. The mechanism resulting in the presence of single chromatids is considered to be precocious division of univalents or dyads at first meiotic anaphase.
三体性是人类最常见的染色体异常类型，对人类病理学的许多方面都有重大影响。它最常见于母本减数分裂I期的“不分离”，但其形成的潜在机制仍不清楚。对处于第二次减数分裂中期的100个单倍体卵母细胞进行分析表明，受精后与三体性形成相容的唯一染色体异常类型是除了整条染色体之外还存在单条染色单体，或者单条染色单体取代了整条染色体。导致单条染色单体存在的机制被认为是第一次减数分裂后期单价体或二价体的早熟分裂。
