Studies on the fatty acid synthesis in maternal and fetal rats.

The fatty acid synthesis as measured by in vitro incorporation of 1-[14C]-acetate and 3H2O into maternal and fetal tissues of the rat has been quantitatively determined. The results showed that because of the endogenous dilution the incorporation of [14C]-acetate does not provide a quantitative measure of fatty acid synthesis. The incorporation of tritium per g of tissue into the fatty acid fraction of maternal and fetal liver (day 21 of pregnancy) was found to be 260 and 130 nmoles per g per min, respectively. The incorporation was lesser in liver of female non-pregnant rats (31 nmoles per g per min) and placenta (4.0 nmoles per g per min). The calculated rates of synthesis of fatty acids were used to support the following views: At the end of gestation about 25% of all fatty acids synthesized within the fetus arise from fetal liver. From day 15 to 21 of pregnancy the fetal fatty acid synthesis supplies about half of the amount of fatty acids which are accumulated due to growth.