...IN SURFACTANT SYNTHESIS IN FETAL RABBIT LUNG ORGAN CULTURE

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. AbstractA basic question in understanding the mechanism of sex differences of fetal surfactant production is whether surfactant synthesis is involved. We studied whether the female fetus synthesizes more surfactant phosphatidylcholine (PC) and saturated phosphatidylcholine (SPC) than the male at the time when the fetal lung is responsive to glucocorticoid. Organ cultures were made of sex specific fetal rabbit lungs of 21 days gestation in Waymouths media +10% charcoal- stripped fetal calf serum卤1O鈭? R dihydrotestosterone (DHT). After 5 days 14C-glycerol卤10鈭? M dexamethasone (dex) was added. After 24 hours lamellar bodies (LB) were isolated by centrifugation in discontinuous, sucrose density gradients. Average LB recovery was 33-36%. 14C-PC and C-SPC were quantitated in the LBs. 14C-SPC was significantly higher in female lungs with or without DHT and was enhanced by dex (No dex: females 198卤71, males 130+55; CPM/mg prot, meaniSD, p .005. Dex: females 389卤65, males 160卤17; p .02). 14C-PC with DHT or dex had similar results. Dex stimulated females but not males. These data indicate that surfactant sex differences result at least in part from differences in synthesis. The cellular mechanisms causing the sex difference appear to be already operative by 21 days gestation in the rabbit and are not further affected by androgen or glucocorticoid. This is important for ultimate elucidation of the mechanism of sex differences in normal fetal cellular development.