Endocrine Abstracts

Cell autonomous sex identity (CASI) of birds is the concept that sex-steroids have little or no effect on the development of secondary sexual characteristics in birds, and that sexual dimorphisms are determined by the sex-chromosome content of cells in individual tissues. In avian species males have a ZZ sex chromosome, while females are ZW. Sexual dimorphisms in chickens, such as muscle mass, comb and wattle size and hackles and spur development are believed to be determined ...