Sex Chromatin Frequency in the Avian Aminon

Conflicting results have been reported on the incidence of sexchromatin in avian cells. In this study the sex chromatin frequenciesare explored in the ammotic cells from two .Leghorn varietiesof domestic fowl, a species which is reported to possess anheterochromatic and late leplicating W sex chromosome. The incidenceof sex chromatin was also examined in the ammotic epitheliumof the Japanese quail throughout the incubation period. Thisspecies of quail possesses a W sex chromosome that is euchromaticat metaphase When the sex chromatin frequencies in the domestic fowl werecompared with the gonadal sex of the embryos, a nuclear sexualdimorphism was apparent with the high frequencies correspondingto embryos of the female sex. No such nuclear sexual dimorphismwas found in the quail, both male and female embryos had approximatelythe same incidence of sex chromatin in their ammotic cells These findings are interpreted in support of the idea that thecytological entity identified as sex chiomatin in the domesticfowl represents the W sex chromosome in the interphase nucleus