In mammals and birds, sex differences in brain function and disease
are thought to
derive exclusively from sex differences in gonadal
hormone secretions. For example, testosterone in male mammals
acts during fetal and neonatal life to cause masculine neural
development. However, male and female brain cells also differ in
genetic sex; thus, sex chromosome genes acting within cells could
contribute to sex differences in cell function. We analyzed the
sexual phenotype of the brain of a rare gynandromorphic finch in
which the right half of the brain was genetically male and the left
half genetically female.
