OXYGEN AND PRENATAL GROWTH

当可育母鸡的蛋从21%的氧气转换到60%的氧气时 在孵育第15天的环境中，胚胎生长和02 在接下来的三天里， 21% 02. 当空气中的O2浓度降低时，发生相反的效果。 在第15天将培养箱从21%切换到15%;胚胎生长 减慢并且胚胎O2消耗福尔斯下降。 这些数据表明氧气 可用性通常限制了鸡胚的生长， 孵化的第15天。 我们建议调查的机制， 其中O2影响胚胎生长和新陈代谢。 我们将探讨 02通过其对生产的作用来改变生长的可能性 已知的合成代谢激素通过测量甲状腺的血浆浓度 激素、胰岛素、禽类生长激素和禽类胰岛素样生长 循环血液中的因素，从15%，21%和21%的胚胎中取样， 60% 02. 我们还将从这些实验组中的每一个添加血浆， 培养的鸡胚成纤维细胞并测量细胞分裂速率， 蛋白质合成和DNA合成。 我们会评估 O2直接作用于细胞水平， 15%02、21%02和60%02鸡胚组织的特征 胚胎与在培养基中生长的培养细胞上获得的数据， 氧张力 我们还将尝试将豚鼠的胎儿发育成哺乳动物 高氧生长刺激模型。 我们将增加02的可用性， 从妊娠第53天开始， 母体血液02容量或降低母体血液02亲和力，或通过 这两个程序的组合，通过比较 胎仔体重以及选定胎仔器官的湿重和干重， 来自对照组的那些已经交叉输血而没有改变血液的人 亲和力或能力。 胎盘血流量的测量 实验和对照动物将在第63天进行，因此 改变血液呼吸特性对母体血流的影响 包括胎盘在内的器官都可以进行评估。 如果02可用性（ 动脉O2含量和胎盘血流量的乘积）没有增加 通过母体血液中的这些变化，我们将增加一个人的红细胞压积， 胎儿，比较其生长与对照组。 如果其中一次干预 引起胎儿生长加速，我们将开始比较02诱导的 在具有O2诱导的生长加速的豚鼠中的生长加速 鸡胚的胚胎。

When fertile hen's eggs are switched from a 21% oxygen to a 60% oxygen environment on the fifteenth day of incubation, embryonic growth and 02 consumption are greater for the next three days than controls maintained at 21% 02. The opposite effects occur when the 02 concentration in the incubator is switched from 21% to 15% on the 15th day; embryonic growth slows and embryonic 02 consumption falls. These data suggest that oxygen availability normally limits the growth of the chick embryo beginning on the 15th day of incubation. We propose to investigate the mechanism by which 02 influences embryonic growth and metabolism. We will explore the possibility that 02 modifies growth through its action on the production of known anabolic hormones by measuring plasma concentrations of thyroid hormones, insulin, avian growth hormone, and avian insulin-like growth factors in circulating blood, taking samples from embryos in 15%, 21% and 60% 02. We will also add plasma from each of these experimental groups to chick embryo fibroblasts in culture and measure the rates of cell division, protein synthesis, and DNA synthesis. We will evaluate the possibility that 02 acts directly at the cellular level by comparing the biochemical characteristics of chick embryo tissues from 15% 02, 21% 02 and 60% 02 embryos with data obtained on cultured cells grown in media with different oxygen tensions. We will also attempt to develop the fetus of the guinea pig as a mammalian model of hyperoxic growth stimulation. We will increase 02 availability to the guines pig fetus beginning on day 53 of pregnancy by increasing maternal blood 02 capacity or decreasing maternal blood 02 affinity, or by a combination of these two procedures, measuring the effects by comparing fetal weight and the wet and dry weights of selected fetal organs with those from controls that have been cross-transfused without altering blood 02 affinity or capacity. Measurements of placental blood flow in experimental and control animals will be made at 63 days so the effects of changing blood respiratory characteristics on the blood flow to maternal organs, including placentas, can be evaluated. If 02 availability (the product of arterial 02 content and placental blood flow) is not increased by these changes in maternal blood, we will increase the hematocrit of one fetus, comparing its growth with controls. If one of these interventions evokes fetal growth acceleration, we will begin to compare 02-induced growth acceleration in the guinea pig with 02-induced growth acceleration of the chick embryo.