Prenatal sex determination by observation of the X-chromatin and the Y-chromatin of exfoliated amniotic fluid cells.

Using direct smears of amniotic fluid cells fixed by the flame drying technic, the validity of sex determination by X-chromatin and Y-chromatin counts has been examined. In 112 cases, the sex determination by examination of the X-chromatin was correct in 109 (97%) and was correct by the Y-chromatin technic in 111 (99%). It is concluded that prenatal sex determination by examination of the X-chromatin or the Y-chromatin from fresh amniotic fluid cells is a valuable, rapid, practical method of prenatal sex determination.