Harding J E, Jones C T, Robinson J S
J Dev Physiol. 1985 Dec;7(6):427-42.
Fetal and placental growth rate in sheep has been manipulated by removal of endometrial caruncles prior to conception. This produced two groups of fetuses, one in which prenatal growth rate was similar to normal and a second group in which the fetuses were about half of the normal size. The mortality in the latter group was high, particularly after catheterisation, and there was evidence of early intra-uterine death and fetal reabsorption. Prior to 125 days the relationship between fetal and placental size was poor, but after 126 days a close correlation between the two was apparent. The small fetuses had comparably small placentas and in all cases there was a close relationship between fetal and placental weight. The experimental growth retardation was associated with hypoglycaemia, hypoxia and hypoinsulinaemia. Plasma T3, T4 and particularly prolactin were very low in the small fetuses whilst levels of cortisol and alanine were high. In contrast to the controls these fetuses showed little evidence of net glucose, alanine or lactate consumption. Infusion of 50% glucose into the pregnant ewe, sufficient to elevate maternal plasma glucose concentrations 2 to 3 fold, caused a comparable increase in the plasma concentrations of normal fetuses but only a 50% rise in the concentration in small fetuses. In contrast administration of 50% O2 to the ewes sufficient to cause a 2 to 3-fold increase in maternal PO2 caused only a small increase of arterial PO2 of normal fetuses but doubled that to normal levels in small fetuses. The results are discussed in relation to the effect of reduced placental size causing a fall in placental and transport and transport capacity and significance of this to the associated fetal growth retardation.
在绵羊受孕前切除子宫内膜肉阜，以此来调控胎儿和胎盘的生长速率。这产生了两组胎儿，一组胎儿的产前生长速率与正常情况相似，另一组胎儿的大小约为正常胎儿的一半。后一组的死亡率很高，尤其是在插管后，并且有早期宫内死亡和胎儿重吸收的迹象。在125天之前，胎儿大小与胎盘大小之间的关系不明显，但在126天之后，两者之间呈现出密切的相关性。小胎儿的胎盘也相对较小，在所有情况下，胎儿体重与胎盘重量之间都存在密切关系。实验性生长迟缓与低血糖、缺氧和低胰岛素血症有关。小胎儿的血浆T3、T4，尤其是催乳素水平非常低，而皮质醇和丙氨酸水平较高。与对照组相比，这些胎儿几乎没有净葡萄糖、丙氨酸或乳酸消耗的迹象。向怀孕母羊输注50%的葡萄糖，足以使母体血浆葡萄糖浓度升高2至3倍，这会使正常胎儿的血浆浓度相应增加，但小胎儿的血浆浓度仅升高50%。相反，向母羊给予50%的氧气，足以使母体PO2升高2至3倍，这只会使正常胎儿的动脉PO2略有增加，但能使小胎儿的动脉PO2加倍至正常水平。本文结合胎盘大小减小导致胎盘转运和运输能力下降的影响，以及这对相关胎儿生长迟缓的意义，对研究结果进行了讨论。
