Abstract
Lung from 19 days' gestation male and female rat fetuses was grown in mixed monolayer culture. Cultures from female lungs synthesized twice as much H-saturated phosphatidylcholine (3H-SPC) from 3H-choline as cultures from male lungs. Preincubation with Cortisol caused a doubling in 3H-SPC synthesis by cultures from both sexes. Study of sex-specific fibroblast cultures revealed significantly higher 11-oxidoreductase activity and basal and cortisone- or cortisol-stimulated fibroblast-pneumonocyte factor activity in female cultures. In contrast to the findings in the fibroblast cultures, sex-specific type II cell cultures showed no difference in basal 3H-SPC synthesis or in response to cortisol-stimulated fibroblast-conditioned medium. Furthermore, the type II alveolar cells had no 11-oxidoreductase activity. These data indicate that there are sex differences in both Cortisol metabolism and fibroblast-pneumonocyte factor production by the fetal lung fibroblast. These differences would lead to a sex difference in the synthesis of pulmonary surfactant.