1. A literature review of the effects of perinatal sex steroids on the development of the brain is presented. It can be shown that the hormones can modify the morphology of discrete areas of the brain.
2. It was concluded that there was a lack of information about how soon these morphological changes appeared.
3. It was therefore decided to study the effects of sex and perinatal hormonal levels on synaptogenesis in a discrete area of the brain.
4. The Suprachiasmatic Nucleus (SON) was chosen for anatomical convenience and because of its role in the photocontrol of ovulation.
5. In this thesis I describe synaptogenesis in the suprachiasmatic nucleus of rats of both sexes ranging from prenatal (20 days of gestation) to adult and in neonatally androgenised females. Preliminary results from neonatally castrated males are also included.
6. Synaptogenesis was studied using morphometric analysis of electron micrographs. It was found that the rate of development of synapses was similar in the SCN of both sexes, but that absolute values in males were higher than in females. Male type development cannot be mimicked by neonatal androgenization but initial results suggest that femal type development can be induced by neonatal castration.
7. My results suggest that both prenatal and postnatal androgens are essential to normal male development
