论文部分内容阅读
除了由新生儿和自发性流产中获悉的大量资料外,现在还有从母亲方面收集到的大量资料,她们是在35岁以上妊娠时接受羊水穿刺检查的。近来对50,000例以上羊水检查结果表明:年逾35岁的妊娠中期妇女中,染色体异常者共约2%左右。性染色质体细胞中能见到的性染色质有两种类型:(1)中期染色中心,它是遗传上灭活和凝缩的 X 染色体,称为 X 染色质(性染色质,Barr 氏小体),见于有1个以上 X 染色体的人。(2)较小而有鲜明荧光的染色中心,以奎吖因染色后,即可由荧光显微镜窥悉。它是人类 Y 染色体上鲜明的荧光区段,有此染色体的人,都能见到。在双倍体细胞中,X 染
In addition to the large amount of information learned from neonatal and spontaneous abortions, there is now a large amount of data collected from mothers who were tested for amniocentesis at the age of 35 and above. Recent results of more than 50,000 amniotic fluid examinations have shown that about 2% of women with a chromosome abnormality are over about 35 years of age. There are two types of sex chromatin that can be seen in sex chromatin cells: (1) The intermediate staining center, which is the genetically inactivated and condensed X chromosome, called X chromatin (sexual chromatin, Barr’s Body), seen in people with more than 1 X chromosome. (2) Small, brightly colored staining centers, stained with quinzoline, can be visualized by fluorescence microscopy. It is a distinct fluorescent segment on the human Y chromosome, and can be seen by anyone with this chromosome. In diploid cells, X staining