ABSTRACT

Cerebellar neurons are generated from the rhombic lip and the neuroepithelium. In this study, we analyze the histogenesis of the cerebellar neuroepithelium in terms of cellular kinetics. The experimental animals are the offspring of pregnant dams injected with 5-bromo-2ʹ-deoxyuridine (BrdU) on embryonic day 13. We infer the fraction of S-phase cells by examining a range of survival times after a single BrdU-exposure and a cumulative BrdU-labeling sequence, which allow for the derivation of cell-cycle parameters and phase durations. The current results indicate that the dose of BrdU employed (35 mg/kg) provides saturation S-phase labeling from at least 1 h after marker delivery. The duration of G2, mitotic phase, and G1 are 1.2, 0.5, and 6.9 h, respectively. The duration for the S-phase, growth fraction, and the whole cycle are obtained on the basis of two proliferative models, steady-state and exponential growth. Both models provided similar results. In conclusion, our results indicate that the steady-state and the cumulative S-phase labeling paradigms can be adopted to analyze cell cycle parameters in the cerebellar neuroepithelium. Current results can help in understanding the regulatory mechanisms of cerebellar histogenesis and the cell biological mechanisms of the proliferative cycle of the neuroepithelium.

摘要

小脑神经元由菱形唇和神经上皮产生。在这项研究中，我们从细胞动力学的角度分析了小脑神经上皮的组织发生。实验动物是在胚胎第 13 天注射 5-bromo-2ʹ-脱氧尿苷 (BrdU) 的怀孕母鼠的后代。我们通过检查单次 BrdU 暴露后的一系列存活时间和一个累积 BrdU 标记序列，允许推导细胞周期参数和相位持续时间。目前的结果表明，使用的 BrdU 剂量 (35 mg/kg) 在标记物递送后至少 1 小时提供饱和 S 相标记。G2、有丝分裂期和 G1 的持续时间分别为 1.2、0.5 和 6.9 小时。S 期的持续时间、生长分数、整个周期是在稳态和指数增长两种增殖模型的基础上得到的。两种模型都提供了相似的结果。总之，我们的结果表明，可以采用稳态和累积 S 期标记范式来分析小脑神经上皮中的细胞周期参数。目前的结果有助于理解小脑组织发生的调控机制和神经上皮细胞增殖周期的细胞生物学机制。