Wright M L, Blanchard L S, Pikula A, Labieniec K E
Biology Department, College of Our Lady of the Elms, Checopee, Massachusetts 01013, USA.
Gen Comp Endocrinol. 1995 Jul;99(1):75-84. doi: 10.1006/gcen.1995.1087.
Rhythmicity of thyroid follicle structure, cell division, and T4 secretion in vitro was studied in anuran tadpoles on a 12L:12D cycle with light onset at 0800 hr. Stage XIII Rana pipiens larvae had a significant circadian rhythm of follicle lumen diameter (acrophase 1052 hr). Follicle cell height was higher at 0900 hr than at other times but the rhythm was not significant. At Stage XX, both follicle cell height (acrophase 2318 hr) and cell division (acrophase 1929 hr) were rhythmic while lumen diameter, though highest at 0900 hr, showed no significant daily changes. Thyroids from Rana catesbeiana larvae at Stages XVII to XVIII had a significant circadian rhythm of T4 secretion (acrophase 2034 hr) in vitro as measured by radioimmunoassay of media collected every 6 hr for 24 hr. The findings indicate that the daily sequence of thyroid structure and function in preclimax Rana tadpoles includes larger follicle lumina early in the light and maximum cell division, T4 secretion, and follicle cell height within a 4-hr interval beginning around the onset of dark.
在12小时光照：12小时黑暗的周期（光照于0800时开始）条件下，研究了无尾类蝌蚪甲状腺滤泡结构、细胞分裂及体外T4分泌的节律性。第XIII阶段的牛蛙幼虫滤泡腔直径具有显著的昼夜节律（高峰相位为1052时）。滤泡细胞高度在0900时高于其他时间，但该节律不显著。在第XX阶段，滤泡细胞高度（高峰相位为2318时）和细胞分裂（高峰相位为1929时）均具有节律性，而腔直径虽在0900时最高，但无显著的每日变化。通过对每隔6小时收集24小时的培养基进行放射免疫测定，发现第XVII至XVIII阶段的牛蛙幼虫甲状腺在体外具有显著的T4分泌昼夜节律（高峰相位为2034时）。研究结果表明，前高峰期牛蛙蝌蚪甲状腺结构和功能的每日顺序包括：在光照早期滤泡腔较大，以及在黑暗开始后约4小时内细胞分裂、T4分泌和滤泡细胞高度达到最大值。
