Owens J A, Falconer J, Robinson J S
J Dev Physiol. 1987 Apr;9(2):137-50.
Endometrial caruncles were excised from 13 sheep (caruncle sheep) before pregnancy to restrict placental growth. In subsequent pregnancies, half the caruncle fetuses were growth retarded or small (weight more than 2 SD below mean weight for control fetuses) with the remainder, normal-sized (weight within 2 SD of mean weight for control fetuses). The caruncle and 16 control sheep, each with indwelling vascular catheters, were studied between 121 and 130 days of pregnancy. Oxygen delivery to and consumption by the pregnant uterus in caruncle sheep with small fetuses was significantly reduced compared to controls while oxygen extraction was significantly increased. Oxygen tension (P02) and content in the common umbilical vein and in the descending aorta were significantly lower in small caruncle fetuses compared to controls but only P02 was lower in normal-sized caruncle fetuses. Oxygen delivery to, and consumption by, the fetus was significantly reduced in normal-sized and in small caruncle sheep compared to controls while oxygen extraction was increased in small caruncle sheep. Utero-placental oxygen consumption was significantly lower in caruncle sheep with small fetuses compared to that in controls. Despite these changes, oxygen consumption by the gravid uterus and fetus, per kg of tissue mass, was similar in both groups of caruncle and in control sheep. Utero-placental oxygen consumption per kg of utero-placental mass in caruncle sheep with small fetuses was not significantly different to that in sheep with normal-sized caruncle or control fetuses, although it averaged only 25% of that in controls. It is concluded that intrauterine growth retardation following restriction of placental growth is associated with a reduced supply of oxygen to both the pregnant uterus and fetus and a redistribution of oxygen to the fetus. This is due to the disproportionate maintenance of fetal growth relative to that of the placenta, since oxygen consumption by either, in terms of tissue mass, was not altered. Further, the greater uterine and fetal extraction of oxygen suggests that a smaller margin of safety may exist between supply and demand in intrauterine growth retardation.
在怀孕前从13只绵羊（肉阜绵羊）身上切除子宫内膜肉阜以限制胎盘生长。在随后的妊娠中，一半的肉阜胎儿生长受限或体型较小（体重比对照胎儿的平均体重低2个标准差以上），其余胎儿体型正常（体重在对照胎儿平均体重的2个标准差范围内）。在妊娠121至130天期间，对肉阜绵羊和16只对照绵羊进行了研究，每只绵羊都留置了血管导管。与对照组相比，怀有小胎儿的肉阜绵羊中，子宫向胎儿输送的氧气量和子宫对氧气的消耗量显著降低，而氧气摄取量显著增加。与对照组相比，小肉阜胎儿的脐静脉和降主动脉中的氧分压（P02）和氧含量显著降低，但正常体型的肉阜胎儿仅P02较低。与对照组相比，正常体型和小肉阜绵羊中胎儿的氧气输送量和消耗量显著降低，而小肉阜绵羊中的氧气摄取量增加。怀有小胎儿的肉阜绵羊的子宫-胎盘耗氧量显著低于对照组。尽管有这些变化，但两组肉阜绵羊和对照绵羊中，每千克组织质量的妊娠子宫和胎儿的耗氧量相似。怀有小胎儿的肉阜绵羊每千克子宫-胎盘质量的子宫-胎盘耗氧量与怀有正常体型肉阜或对照胎儿的绵羊相比无显著差异，尽管其平均仅为对照组的25%。得出的结论是，胎盘生长受限后发生的宫内生长迟缓与妊娠子宫和胎儿的氧气供应减少以及氧气向胎儿的重新分配有关。这是由于胎儿生长相对于胎盘生长的维持不成比例，因为就组织质量而言，两者的耗氧量没有改变。此外，子宫和胎儿对氧气的更大摄取表明，宫内生长迟缓时供应与需求之间的安全边际可能较小。
