[Improvement of a chromosomal technic for trophoblast biopsy. Apropos of 200 cases]

The authors report their experience of 200 cases of prenatal diagnosis by biopsy of chorionic villi. Because they could not consistently obtain good quality chromosome banding, they propose a modification of the conventional direct method. The addition of methanol in sufficient proportions to the nuclear suspension makes it possible to obtain spontaneous spreading on slides heated to 65 degrees C and eliminates the problems of mechanical spreading.