Shand J H, Noble R C
Biol Neonate. 1979;36(5-6):298-304. doi: 10.1159/000241243.
Although the fatty acid compositions of the total lipids of the sheep placenta and fetal plasma were shown to be broadly similar, they differed significantly from the fatty acid composition of the maternal plasma unesterified fatty acids, the plasma lipid component from which the fetus derives almost all of its requirements for pre-formed fatty acids. In particular, the placental and fetal plasma lipids displayed a 3-fold higher oleic acid/stearic acid ratio and contained a significantly higher proportion of arachidonic acid than the maternal unesterified fatty acids. These differences correlated well with the high delta 9- and delta 6-desaturase activities, respectively, shown to be present in sheep placental tissue in vitro. The levels of these enzymes in placental tissue contrasted with the relatively low desaturase activities found to be present in adult and neonatal sheep liver and in the placentas of other, non-ruminant, species. The possible role of such high levels of desaturase activity in the sheep placenta is discussed in relation to the particularly poor essential fatty acid status imposed upon the fetal ruminant.
尽管已表明绵羊胎盘和胎儿血浆中总脂质的脂肪酸组成大致相似，但它们与母体血浆未酯化脂肪酸的脂肪酸组成存在显著差异，胎儿几乎所有预先形成的脂肪酸需求都来自母体血浆脂质成分。特别是，胎盘和胎儿血浆脂质的油酸/硬脂酸比值高出3倍，且花生四烯酸的比例明显高于母体未酯化脂肪酸。这些差异分别与体外绵羊胎盘组织中显示的较高的Δ9-和Δ6-去饱和酶活性密切相关。胎盘组织中这些酶的水平与成年和新生绵羊肝脏以及其他非反刍动物胎盘相对较低的去饱和酶活性形成对比。结合反刍动物胎儿特别差的必需脂肪酸状况，讨论了绵羊胎盘中如此高水平的去饱和酶活性可能发挥的作用。
