The sex of a baby is determined primarily by the two sex chromosomes. In normal male cells, there's an X and a Y sex chromosome. In normal female cells there are two X chromosomes.
Initially, the embryonic tissue that later becomes testes in boys or ovaries in girls is undifferentiated. At around six to eight weeks of pregnancy, the presence of a Y chromosome causes this tissue to develop into testes. If there's no Y chromosome, ovaries develop.
As well as the hormones released by the testes and ovaries, which determine whether we grow into boys or girls, hormones also influence brain development and behaviour.
Most of the brain is similar in males and females, but some regions such as the hypothalamus and amygdala, which control functions related to sexuality, differ between the sexes. In these tissues there are receptors or receiving units that allow the cells to respond to androgens, or male sex hormones.
Early hormone environment permanently influences behaviour. Girls exposed to high levels of androgens in the womb show more interest in toys such as cars and less interest in dolls, are more likely to prefer boys as playmates and engage in male-typical rough-and-tumble play.
No comments:
Post a Comment