French K A, Kristan W B
Dept of Biology, University of California, San Diego 92093-0322.
Trends Neurosci. 1992 May;15(5):169-74. doi: 10.1016/0166-2236(92)90168-8.
A pair of Retzius neurons is found in each segmental midbody ganglion of the CNS of the leech Hirudo medicinalis. Although all Retzius neurons appear to have the same cell lineage and are indistinguishable from one another through the initial phases of axonogenesis, later in development two pairs of Retzius neurons--those in the segments containing the male and female reproductive ducts--acquire distinctive morphological and physiological characteristics. Experimental manipulations of the reproductive ducts in early embryos have indicated that the outgrowing Retzius axons receive a signal from these peripheral targets that triggers major changes in their developmental program. Such 'end-organ specification' has been shown to contribute to the differentiation of neurons in other nervous systems as well, and the mechanisms underlying such control can be investigated in great detail in the relatively simple, segmented nervous system of the leech.
在医用水蛭中枢神经系统的每个节段性中体神经节中都能发现一对雷悌氏神经元。尽管所有雷悌氏神经元似乎都具有相同的细胞谱系，并且在轴突发生的初始阶段彼此无法区分，但在发育后期，两对雷悌氏神经元——即位于包含雄性和雌性生殖管道的节段中的神经元——获得了独特的形态和生理特征。对早期胚胎中生殖管道的实验操作表明，正在生长的雷悌氏轴突从这些外周靶点接收一种信号，该信号触发其发育程序的重大变化。这种“终末器官特化”也已被证明在其他神经系统中对神经元的分化也有作用，并且在水蛭相对简单的分节神经系统中，可以非常详细地研究这种控制的潜在机制。
