Fitzgerald M
Nature. 1987;326(6113):603-5. doi: 10.1038/326603a0.
The first movements of the fetus are apparently random and spontaneous. Their onset coincides with the growth of dorsal root afferents into the spinal cord and it is possible that they are not simply a result of spontaneous motoneuron activity but are reflex responses to sensory stimulation. It is not clear what stimuli could normally evoke such reflexes because nothing is known of the properties of primary afferent neurons in the fetus. I have investigated this by making recordings from single dorsal root ganglion cells in fetal rats in vivo. The afferents have small, defined receptive fields and respond to mechanical stimulation of skin or muscle at intensities that might occur in utero. Many of them are also chemosensitive. Unlike postnatal afferents they display background activity which peaks at the same age as fetal movements. Repeated stimulation causes long-lasting increases of both background and evoked activity. Such sensory input is likely to have a considerable influence on fetal movements and on the development of spinal cord connections.
胎儿的最初运动显然是随机且自发的。它们的开始与背根传入神经向脊髓的生长同时发生，并且有可能它们不仅仅是自发运动神经元活动的结果，而是对感觉刺激的反射反应。目前尚不清楚通常哪些刺激能够引发此类反射，因为对于胎儿初级传入神经元的特性一无所知。我通过在活体胎鼠的单个背根神经节细胞上进行记录对此进行了研究。这些传入神经具有小的、明确的感受野，并且对子宫内可能出现的强度的皮肤或肌肉机械刺激有反应。它们中的许多也对化学物质敏感。与出生后的传入神经不同，它们表现出背景活动，其在与胎儿运动相同的年龄达到峰值。重复刺激会导致背景活动和诱发活动的长期增加。这种感觉输入可能对胎儿运动以及脊髓连接的发育有相当大的影响。
