Voronezhskaya E E, Hiripi L, Elekes K, Croll R P
Institute of Developmental Biology, Russian Academy of Sciences, Moscow.
J Comp Neurol. 1999 Feb 15;404(3):285-96. doi: 10.1002/(sici)1096-9861(19990215)404:3<285::aid-cne1>3.0.co;2-s.
The embryonic development of the catecholaminergic system of the pond snail, Lymnaea stagnalis, was investigated by using chromatographic and histochemical methods. High performance liquid chromatography suggested that dopamine was the only catecholamine present in significant concentrations throughout the embryonic development of Lymnaea. Dopamine first became detectable at about embryonic stage (E) 15 (15% of embryonic development) and then increased in amount during early development to reach about 120-140 fmol per animal by around E40. Dopamine content remained stable during mid-embryogenesis (E40-65), increased slowing for the next couple of days, and then increased rapidly to culminate at about 400 fmol per animal by hatching. The detection of aldehyde- and glyoxylate-induced fluorescence and of tyrosine hydroxylaselike immunoreactivity indicated that the first catecholaminergic cells appeared in the late trochophore or early veliger stage of embryonic development (E32-35). The paired perikarya of these transient apical catecholaminergic (TAC) neurons were located beneath the apical plate, remained outside of the central ganglia during embryogenesis, and no longer contained detectable catecholamines close to hatching. TAC neurons bore cilia on the ends of short processes that penetrated the overlying epithelium; their long processes branched repeatedly under the ciliated apical plate. Several smaller catecholaminergic cells first appeared in the anterior margin of the foot at a stage when the embryos began to metamorphose from the veliger form (E55). Similar bipolar cells later appeared in the tentacle and lips. The axons of all of these small peripheral cells projected centrally and terminated within the neuropil of different central ganglia. Central catecholaminergic neurons, including RPeD1, differentiated only after metamorphosis was complete (E75). Development of locomotor, respiratory, and feeding behaviors correlated with maturation of catecholaminergic neurons, as indicated by histology and chromatography.
运用色谱法和组织化学方法，对椎实螺（Lymnaea stagnalis）儿茶酚胺能系统的胚胎发育进行了研究。高效液相色谱法表明，多巴胺是椎实螺胚胎发育全过程中唯一以显著浓度存在的儿茶酚胺。多巴胺最早在胚胎期（E）15左右（胚胎发育的15%）可被检测到，随后在早期发育过程中含量增加，到E40左右每只动物达到约120 - 140飞摩尔。在胚胎中期（E40 - 65）多巴胺含量保持稳定，接下来的几天缓慢增加，然后迅速增加，到孵化时每只动物达到约400飞摩尔的峰值。醛和乙醛酸诱导荧光以及酪氨酸羟化酶样免疫反应性的检测表明，最早的儿茶酚胺能细胞出现在胚胎发育的晚期担轮幼虫或早期面盘幼虫阶段（E32 - 35）。这些短暂的顶端儿茶酚胺能（TAC）神经元的成对胞体位于顶板下方，在胚胎发育过程中位于中枢神经节之外，临近孵化时不再含有可检测到的儿茶酚胺。TAC神经元在穿透上层上皮的短突起末端有纤毛；它们的长突起在有纤毛的顶板下反复分支。在胚胎开始从面盘幼虫形态变态时（E55），几只较小的儿茶酚胺能细胞首先出现在足部前缘。类似的双极细胞随后出现在触手和唇部。所有这些小的外周细胞的轴突向中枢投射并终止于不同中枢神经节的神经纤维网内。包括RPeD1在内的中枢儿茶酚胺能神经元仅在变态完成后（E75）才分化。组织学和色谱分析表明，运动、呼吸和摄食行为的发育与儿茶酚胺能神经元的成熟相关。
