Growth hormone as an autocrine/paracrine factor in chick embryogenesis: an retinal model

这一建议是对生长激素分泌和作用的生理研究正在进行的计划的延伸。在出生后的发育过程中，生长激素从脑垂体（位于大脑底部）分泌到血液中，并通过血液进入身体的每一个组织。这些组织表达介导垂体GH对细胞生长和分化的作用的受体。然而，虽然垂体GH的这些“内分泌”作用对出生后发育是必需的，但胚胎或胎儿生长被认为是一种“无GH生长综合征”，因为它发生在循环系统发育和垂体分化之前。因此，胚胎或胎儿生长被认为是由组织生长因子局部诱导的。然而，胚胎中的生长可能不是“矛盾的”，因为它可能是由早期胚胎组织中产生的生长激素的局部作用介导的。

This proposal is an extension of an ongoing program of research on the physiology of GH secretion and action. In postnatal development, GH is secreted from the pituitary gland (at the base of the brain) into the bloodstream, through which it gains access to every tissue in the body. These tissues express receptors that mediate the actions of pituitary GH on cellular growth and differentiation. However, while these 'endocrine' actions of pituitary GH are obligatory for postnatal development, embryonic or fetal growth is thought to be a 'growth-without-GH-syndrome', since it occurs prior to the development of the circulatory system and the differentiation of the pituitary gland. Embryonic or fetal growth is thus thought to be induced locally by tissue growth factors. Growth in the embryo may not, however, be 'paradoxical' since it may be mediated by local actions of GH produced in early embryonic tissues.