Phelps P E, Brennan L A, Vaughn J E
Division of Neurosciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010.
Brain Res Dev Brain Res. 1990 Oct 1;56(1):63-74. doi: 10.1016/0165-3806(90)90165-u.
Combined [3H]thymidine autoradiographic and choline acetyltransferase (ChAT)-immunocytochemical techniques were used to answer questions concerning the generation of specific classes and subclasses of cholinergic neurons in rat brainstem. First, the generation of rostrally and caudally located neurons of the same class (i.e. somatic efferent oculomotor and hypoglossal nuclei, respectively) were compared. Results indicated that, although embryonic day 11 (E11) was the peak birthday for both nuclei, hypoglossal neurons were generated significantly earlier than oculomotor neurons, indicating a caudorostral generation gradient for brainstem somatic motor nuclei. Second, the generation patterns of 3 different subclasses of motor neurons at the same brainstem level were compared; namely those of the somatic efferent hypoglossal nucleus (XII), the general visceral efferent dorsal nucleus of the vagus (X), and the predominantly special visceral efferent nucleus ambiguus. All 3 subclasses of cholinergic cells had the same peak day (E11) and overall period of generation (E11-12). However, statistical analyses indicated a precocious generation of nucleus ambiguus, but no developmental differences between N, XII and N. X. It is suggested that nucleus ambiguus is formed earlier than N. XII and N. X, due to its more ventral location within a ventrodorsal neurogenetic gradient. Third, the generation patterns of different classes of large cholinergic neurons were examined. Specifically, the birthdays of cholinergic non-motor projection neurons of the pedunculopontine-laterodorsal tegmental nuclei (PPT-LDT) were contrasted to those of the cholinergic brainstem motor neurons. The peak birthdays of both rostrally and caudally located motor neurons were two days earlier than those of the PPT-LDT neurons. Thus, large cholinergic cells projecting to peripheral targets are born significantly earlier than those projecting within the CNS, even though the former are located more rostrally on the caudorostral neurogenetic gradient. This represents an apparent exception to the emerging rule that cholinergic neurons obey the general gradients of neurogenesis manifest in the regions of the central nervous system where they reside.
采用联合[³H]胸腺嘧啶核苷放射自显影术和胆碱乙酰转移酶（ChAT）免疫细胞化学技术，以解答有关大鼠脑干胆碱能神经元特定类别和亚类生成的问题。首先，比较了同一类中位于头端和尾端的神经元（分别为躯体传出性动眼神经核和舌下神经核）的生成情况。结果表明，虽然胚胎第11天（E11）是这两个核的生成高峰期，但舌下神经核神经元的生成明显早于动眼神经核神经元，表明脑干躯体运动核存在从尾端到头端的生成梯度。其次，比较了脑干同一水平的3种不同亚类运动神经元的生成模式；即躯体传出性舌下神经核（XII）、一般内脏传出性迷走神经背核（X）和主要为特殊内脏传出性疑核的生成模式。胆碱能细胞的所有这3个亚类都有相同的高峰期（E11）和总的生成期（E11 - 12）。然而，统计分析表明疑核生成早熟，但在N、XII和X核之间没有发育差异。有人提出，疑核因其在腹背神经发生梯度中位置更靠腹侧，所以比N. XII和N. X形成更早。第三，研究了不同类大胆碱能神经元的生成模式。具体而言，将脚桥核 - 外侧背盖核（PPT - LDT）的胆碱能非运动投射神经元的生成时间与脑干胆碱能运动神经元的生成时间进行了对比。头端和尾端的运动神经元的生成高峰期都比PPT - LDT神经元早两天。因此，投射到外周靶标的大胆碱能细胞的生成明显早于投射到中枢神经系统内的细胞，尽管前者在尾到头的神经发生梯度上位置更靠头端。这似乎是一个新出现的规律的明显例外，该规律是胆碱能神经元遵循它们所在的中枢神经系统区域中神经发生的一般梯度。
