为进行孕早期的产前诊断,目前应用的方法是把绒毛膜绒毛培养24小时之后,直接进行细胞遗传学分析。应用这种方法,绒毛组织有丝分裂相出现率很高。假设,用这种直接法获得的有丝分裂中期细胞是来源于胎儿,那么就不必去仔细选择完整绒毛。然而,最近又有报告,直接制备染色体标本时 For the first trimester of pregnancy prenatal diagnosis, the current application of the method is to chorionic villi cultured for 24 hours, direct cytogenetic analysis. Using this method, chorionic tissue mitosis phase occurs very high. Assuming that metaphase cells obtained by this direct method are derived from the fetus, then it is not necessary to carefully select the complete villi. However, there have been recent reports of direct preparation of chromosome specimens