Improved methods of direct and cultured chromosome preparations from chorionic villous samples.

A new method is described for preparing direct mitotic chromosome spreads from chorionic villous samples, which has resulted in sufficiently high yields of well-banded metaphases to permit a complete standard chromosomal diagnosis in 20 of 20 cases. A method of establishing monolayer cultures from this material that can be harvested from 3 to 7 days after initiation is also presented.