Ross M G, Nijland M J
Department of Obstetrics and Gynecology, University of California Los Angeles, School of Medicine, Harbor-University of California Los Angeles Medical Center, Torrance 90502, USA.
Am J Physiol. 1998 Apr;274(4):R879-93. doi: 10.1152/ajpregu.1998.274.4.R879.
Swallowing represents a primary physiological function that provides for the ingestion of food and fluid. In precocial species, swallowing activity likely develops in utero to provide for a functional system during the neonatal period. The chronically instrumented ovine fetal preparation has provided the opportunity for recent advances in understanding the regulation of in utero swallowing activity. The near-term ovine fetus swallows fluid volumes (100-300 ml/kg) that are markedly greater, per body weight, than that of the adult (40-60 ml/kg). Spontaneous in utero swallowing and ingestive behavior contribute importantly to the regulation of amniotic fluid volume and composition, the acquisition and potential recirculation of solutes from the fetal environment, and the maturation of the fetal gastrointestinal tract. Fetal swallowing activity is influenced by fetal maturation, neurobehavioral state alterations, and the volume of amniotic fluid. Furthermore, intact dipsogenic mechanisms (osmolality, angiotensin II) have been demonstrated in the near-term ovine fetus. It remains unknown to what degree, if any, fetal swallowing may be influenced by nutrient appetite, salt appetite, or taste. Nevertheless, the development of dipsogenic and additional regulatory mechanisms for ingestive behavior occurs during fetal life and may be susceptible to changes in the pregnancy environment. This review describes what is currently known regarding the in utero development of ingestive behavior and the importance of this activity for fetal and perhaps ultimately adult fluid homeostasis.
吞咽是一项主要的生理功能，用于摄取食物和液体。在早成雏物种中，吞咽活动可能在子宫内就已发展，以便在新生儿期提供一个功能系统。长期植入仪器的绵羊胎儿模型为了解子宫内吞咽活动的调节提供了新的契机。接近足月的绵羊胎儿每体重所吞咽的液体量（100 - 300毫升/千克）明显高于成年羊（40 - 60毫升/千克）。子宫内的自发吞咽和摄食行为对羊水的体积和成分调节、胎儿环境中溶质的获取和潜在再循环以及胎儿胃肠道的成熟起着重要作用。胎儿的吞咽活动受胎儿成熟度、神经行为状态改变以及羊水量的影响。此外，在接近足月的绵羊胎儿中已证实存在完整的致渴机制（渗透压、血管紧张素II）。尚不清楚胎儿吞咽在何种程度上（如果有的话）可能受营养食欲、盐食欲或味觉的影响。然而，致渴和其他摄食行为调节机制在胎儿期就已发展，并且可能易受妊娠环境变化的影响。本综述描述了目前关于子宫内摄食行为发育的已知情况，以及该活动对胎儿乃至最终对成人体液稳态的重要性。
