HORMONAL CONTROL OF GROWTH

有相当数量的人类新生儿在出生时比正常新生儿小。 这些婴儿的健康状况较差，且死亡率高于 体重正常。关于调节胎儿生长的激素的信息是 稀疏性和矛盾性，对可能的可能性几乎一无所知 激素对哺乳动物胚胎宫内生长的影响。有意义的 关于这些对象的信息可能会使人类胎儿生长的发生率 迟缓现象有待减少。我们将研究荷尔蒙 大鼠在胚胎、胎儿时期的生长和分化所需 和新生儿期，使用我们开发的新技术。其中之一 这涉及到将整个早期胚胎或胎儿的爪子移植到 幼年或成年同基因大鼠肾胶囊。在这个网站上 移植的组织生长良好，分化正常。我们以前的 研究表明，胎鼠组织的生长需要胰岛素(I)和 生长抑素(SM)。我们将研究胚胎组织何时发育成 通过将胚胎移植到宿主体内来依赖这些激素 糖尿病(D)或垂体切除(HX)。后者是SM 有缺陷。我们还表明，出生后的某个时候， 大鼠对甲状腺激素(TH)和生长激素(GH)的依赖 成长。我们将通过移植来调查这种依赖何时出现 月龄新生大鼠肾被膜下剑突软骨 正常、HX或切除甲状腺(TX)的宿主大鼠。在…方面的分歧 移植物在TX和HX宿主中的生长曲线将表明 当他们分别开始依赖GH(或SM)和TH时。直接式 促生长激素(I、SM、TH和GH)对体内生长的影响 来自胚胎、胎儿和新生儿的移植组织的 使用一种新的输液程序进行了研究。这些组织被移植到 在宿主大鼠的双肾被膜下，即HX或D。 插入通往一个肾脏的动脉，并注入激素溶液 通过渗透性的小泵进入插管的肾动脉。因此， 输注肾上的移植手术会受到 而对侧肾脏的移植不受影响。 我们还将测试激素对人体生长的直接促进作用 幼年和成年大鼠，通过将溶液注入HX或D 右股动脉。比较右腿组织的生长情况 到左腿(未输液)。将生长激素注入体内的可能性 还将对HX大鼠一条腿产生SM进行调查。

A significant number of human neonates are smaller than normal at birth. These infants are less healthy and have a higher mortality than neonates of normal weight. Information on hormones that regulate growth of fetuses is sparse and contradictory, and virtually nothing is known about possible hormonal effects on the growth of mammalian embryos in utero. Meaningful information on these subjects may allow the incidence of human fetal growth retardation to be reduced. We will investigate the hormones that are required for growth and differentiation of rats during the embryonic, fetal and neonatal periods using new techniques that we have developed. One of these involves transplanting whole early embryos, or fetal paws under the kidney capsule of juvenile or adult syngeneic rats. At this site transplanted tissue grows well and differentiates normally. Our previous work indicates that growth of fetal rat tissues requires insulin (I) and somatomedins (SM). We will investigate when embryonic tissue develops a dependence on these hormones by transplanting embryos into hosts that are either diabetic (D) or hypophysectomized (HX). The latter are SM deficient. We have also shown that sometime after birth the tissues of the rat become dependent on thyroid hormones (TH), and growth hormone (GH) for growth. We will investigate when this dependence emerges by transplanting xiphoid cartilage from neonatal rats under the kidney capsule of month-old host rats which are intact, HX or thyroidectomized (TX). A divergence in the growth curves of the transplants in the TX and HX hosts will indicate when they became dependent on GH (or SM) and TH, respectively. The direct effects in vivo of growth promoting hormones (I, SM, TH and GH) on growth of transplanted tissue from embryos, fetuses and neonates will be investigated using a new infusion procedure. The tissues are transplanted under the capsule of both kidneys of host rats which are either HX or D. The artery to one kidney is cannulated and hormone solutions are infused into the cannulated renal artery via an osmotic minipump. Thus the transplants on the infused kidney are exposed to direct effects of the hormone while the transplants on the contralateral kidney are unaffected. We will also test the direct growth promoting effects of hormones in juvenile and adult rats that are HX or D by infusing solutions into the right femoral artery. Growth of the tissues on the right leg is compared to that in the left (uninfused) leg. The possibility that infusing GH into one leg of HX rats will cause production of SM will also be investigated.