The major premise of this proposal is to study biochemically the hormonal and metabolic regulation of glycogen turnover and lecithin production in the lungs of fetal rats during the terminal stages of gestation under both in vivo and in vitro conditions. Studies will be directed at enzymic adaptations that take place in fetal lung tissue in response to corticosterone, thyroxine, growth hormone, prostaglandins E and F, HCG and TSH treatment. In vitro organ culture studies will enable us to evaluate more directly the role of nutrients on fetal lung maturation processes. In addition, the short and long term effects of intraamniotically administered glucocorticoid on the steroidogenic capacity of the fetal-placental unit in the pregnant monkey will be studied. It is hoped that this research will provide further insight into the hormonal and nutritive requirements of the maturing fetal lung which will have direct bearing on understanding the etiology of hyaline membrane disease and the respiratory distress syndrome and their therapeutic management.