Becker U G, Vollrath L
J Neural Transm. 1983;56(2-3):211-21. doi: 10.1007/BF01243279.
In two experiments carried out on two alternate days, the 24-h-rhythmicity of pineal gland volume, pinealocyte nuclear size in cortex and medulla and mitotic activity were studied in male Sprague-Dawley rats, to assess to what extent morphological parameters reflect the pronounced day/night differences in pineal melatonin formation. Pineal volume exhibited statistically significant changes in the second experiment only, with a distinct trough at 6 p.m. Karyometry revealed highly variable patterns. In the first experiment, pinealocyte nuclear changes lacked parallelism in cortex and medulla. The cortex exhibited a bimodal curve with peaks at noon of the first day and at 6 a.m. of the second day, and two troughs at 6 a.m. and midnight respectively of the first day. The medulla showed no clear-cut rhythmicity. In the second experiment, cortex and medulla reacted similarly, nuclear size decreasing from 6 a.m. to 6 p.m., remaining low thereafter. Mitotic activity of pinealocytes is low (on average 23 mitotic figures/gland). In both experiments statistically significant differences existed between certain times, pointing in the direction of 24-h-rhythmicity, but whereas the curve exhibited a peak at midnight in the first experiment, mitotic activity in the second experiment showed a trough at midnight. It is concluded that for as yet unexplained reasons morphological parameters do not appear to accurately reflect circadian rhythmicity of pineal melatonin formation.
在连续两天进行的两项实验中，对雄性斯普拉格-道利大鼠松果体体积、皮质和髓质中松果体细胞的核大小以及有丝分裂活性的24小时节律进行了研究，以评估形态学参数在多大程度上反映了松果体褪黑素形成中明显的昼夜差异。松果体体积仅在第二项实验中表现出统计学上的显著变化，下午6点有一个明显的低谷。核测量显示出高度可变的模式。在第一项实验中，皮质和髓质中松果体细胞的核变化缺乏平行性。皮质呈现双峰曲线，第一天中午和第二天上午6点出现峰值，第一天上午6点和午夜分别出现两个低谷。髓质没有明显的节律性。在第二项实验中，皮质和髓质的反应相似，核大小从上午6点到下午6点减小，此后保持较低水平。松果体细胞的有丝分裂活性较低（平均每个腺体23个有丝分裂图像）。在两项实验中，特定时间之间存在统计学上的显著差异，表明存在24小时节律，但第一项实验中曲线在午夜出现峰值，而第二项实验中有丝分裂活性在午夜出现低谷。结论是，由于尚未解释的原因，形态学参数似乎不能准确反映松果体褪黑素形成中的昼夜节律。
