在G显带的淋巴细胞分裂中期标本上,研究了正常人与21三体患者的染色体核仁形成区形成随体联合的能力。21名(9女,12男)具有正常核型的个体作对照组,19名(8女,11男)为21三体患者。每一正常个体约计数10~3细胞,21三体患者约计数4×10~2细胞,如果2个(或2个以上)近端着丝粒染色体的随体末端彼此位于1.2微米之内,就看作近端着丝粒 On G-banding lymphocyte metaphase specimens, the ability of the chromosomal nucleolar regions of normal and trisomy 21 to form satellite-associated regions was studied. Twenty-one (9 female, 12 male) individuals with normal karyotype served as controls and 19 (8 female, 11 males) were trisomy 21 patients. Each normal individual counts about 10 to 3 cells and the trisomy 21 counts about 4 × 10 2 cells. If the two or more proximal centromere ends are within 1.2 μm of each other, It is considered as centromere