Usson Y, Saxod R
Laboratoire de Biologie Animale, Université Joseph Fourier, Grenoble, France.
J Neurocytol. 1988 Oct;17(5):639-48. doi: 10.1007/BF01260991.
The proliferation of Schwann cells in the sciatic nerve of chick was studied from day 11 to day 27 of development in control and thyroid-deficient embryos. Hypothyroidism was induced by tetramethylthiourea injection on days 8 and 19 of incubation. The parameters of the cell cycle were determined using autoradiographs (tritiated thymidine) and by image analysis of Feulgen-stained nuclear smears. The duration of the cell cycle was lengthened and the growth fraction was reduced in hypothyroid animals, at 11 and 15 days of incubation. At later stages (days 21 and 27), these parameters were not significantly different from the controls as if the sensitivity of Schwann cells to thyroid hormones was scheduled to occur during a limited period of development. The total number of axons was the same in control and hypothyroid animals suggesting that the slowing down of Schwann cell proliferation is not a consequence of neuronal cell death. The consequence of that slowing down is a delay in the isolation of promyelin axons and a reduction in the proportion of myelinated axons at all the stages studied.
在对照胚胎和甲状腺功能减退胚胎中，研究了从发育第11天到第27天鸡坐骨神经中雪旺细胞的增殖情况。在孵化的第8天和第19天注射四甲基硫脲诱导甲状腺功能减退。使用放射自显影片（氚标记胸腺嘧啶核苷）并通过对福尔根染色的核涂片进行图像分析来确定细胞周期参数。在孵化第11天和15天时，甲状腺功能减退动物的细胞周期持续时间延长，生长分数降低。在后期阶段（第21天和第27天），这些参数与对照组无显著差异，似乎雪旺细胞对甲状腺激素的敏感性预定在有限的发育时期出现。对照动物和甲状腺功能减退动物的轴突总数相同，这表明雪旺细胞增殖减慢不是神经元细胞死亡的结果。这种减慢的结果是在所有研究阶段中前髓鞘轴突隔离延迟以及有髓鞘轴突比例降低。
