Crawford M A, Hassam A G, Williams G
Lancet. 1976 Feb 28;1(7957):452-3. doi: 10.1016/s0140-6736(76)91476-8.
The fetal brain accumulates long-chain (C20 and 22) polyunsaturated fatty acids--arachidonic and docosahexaenoic--during cell division. De-novo synthesis of these acids does not occur and they are thought to be either directly derived from food or by metabolism from linoleic and linolenic acids, respectively. Administration of isotopically labelled linoleic and linolenic acids to pregnant guineapigs showed that only a small proportion of the label was converted to their respective long-chain polyunsaturated derivatives in the maternal liver. The proportion was increased within the phospholipids (structural lipids) by what appeared to be amultiple processing system which increased chain length and degree of polyunsaturation from maternal liver to placenta, fetal liver, and to fetal brain. Observations in man suggest a similar trend. The porportion of long-chain polyunsaturated acids increased in the phospholipids from maternal blood, cord blood, fetal liver, and fetal brain. These data show that the placenta and fetus are radically modifying the maternal phospholipids so as to achieve the high proportions of the C20 and C22 polyunsaturated fatty acids in the structural lipids of the developing brain.
胎儿大脑在细胞分裂过程中会积累长链（C20和C22）多不饱和脂肪酸——花生四烯酸和二十二碳六烯酸。这些酸不会从头合成，人们认为它们要么直接来源于食物，要么分别由亚油酸和亚麻酸代谢而来。给怀孕的豚鼠注射同位素标记的亚油酸和亚麻酸后发现，只有一小部分标记物在母体肝脏中转化为各自的长链多不饱和衍生物。在磷脂（结构脂质）中，这一比例通过一个似乎是多重加工系统而增加，该系统从母体肝脏到胎盘、胎儿肝脏，再到胎儿大脑，增加了链长和多不饱和程度。对人类的观察表明了类似的趋势。长链多不饱和酸在母体血液、脐带血、胎儿肝脏和胎儿大脑的磷脂中的比例增加。这些数据表明，胎盘和胎儿正在从根本上改变母体磷脂，以便在发育中大脑的结构脂质中实现高比例的C20和C22多不饱和脂肪酸。
