Antenatal Sex Determination in Macaca Arctoides

Transabdominal amniocentesis was performed on 11 Macaca arctoides, between the 10th and 20th weeks of gestation, for the purpose of antenatal sex determination. The technique employing Y-chromatin fluorescence was unsuccessful in predicting sex, but the sexes were differentiated with complete accuracy by examining amniotic cells stained by a modified Papanicolaou technique. Of the cells from male fetuses, fewer than 10% contained X-chromatin (Barr bodies); of those from females, more than 45% contained X-chromatin.