Fowden A L
Physiological Laboratory, Cambridge, UK.
Reprod Fertil Dev. 1995;7(3):351-63. doi: 10.1071/rd9950351.
Hormones have an important role in the control of fetal growth. They act on both tissue accretion and differentiation and enable a precise and orderly pattern of growth to occur during late gestation. In part, their actions on growth may be mediated by other growth factors such as the insulin-like growth factors (IGFs). Insulin stimulates fetal growth by increasing the mitotic drive and nutrient availability for tissue accretion. It has little effect on tissue differentiation. In contrast, the main effects of cortisol in utero are on tissue differentiation and maturation. Cortisol appears to act directly on the cells to alter gene transcription or post-translational processing of the gene products. Cortisol may also initiate the transition from the fetal to the adult modes of growth regulation by inducing the switch from IGF-II to IGF-I gene expression in the fetal liver. Thyroxine affects both tissue accretion and differentiation in the fetus by a combination of metabolic and non-metabolic mechanisms. Pituitary growth hormone, on the other hand, appears to have little part in the control of fetal growth, unlike its role postnatally. Fetal hormones, therefore, promote growth and development in utero by altering both the metabolism and gene expression of the fetal tissues. These hormonal actions ensure that fetal growth rate is commensurate with the nutrient supply and that prepartum maturation occurs in preparation for extrauterine life.
激素在胎儿生长控制中起着重要作用。它们作用于组织增生和分化，使妊娠后期出现精确且有序的生长模式。其对生长的作用部分可能由其他生长因子介导，如胰岛素样生长因子（IGFs）。胰岛素通过增加有丝分裂驱动力和组织增生所需的营养物质供应来刺激胎儿生长。它对组织分化影响很小。相比之下，子宫内皮质醇的主要作用是在组织分化和成熟方面。皮质醇似乎直接作用于细胞，改变基因转录或基因产物的翻译后加工。皮质醇还可能通过诱导胎儿肝脏中从IGF-II基因表达向IGF-I基因表达的转变，启动从胎儿生长调节模式向成人生长调节模式的转变。甲状腺素通过代谢和非代谢机制的结合，影响胎儿的组织增生和分化。另一方面，垂体生长激素在胎儿生长控制中似乎作用不大，这与它在出生后的作用不同。因此，胎儿激素通过改变胎儿组织的代谢和基因表达，促进子宫内的生长和发育。这些激素作用确保胎儿生长速度与营养供应相匹配，并确保产前成熟，为宫外生活做好准备。
