两种软体动物神经系统一氧化氮合酶的组织化学定位

Histochemical Localization of Nitric Oxide Synthase in the Nervous Systems of two Molluscs

运用一氧化氮合酶 (NOS)组织化学方法研究了软体动物门双壳纲种类中国蛤蜊和腹足纲种类嫁神经系统中NOS阳性细胞以及阳性纤维的分布。结果表明 :在蛤蜊脑神经节腹内侧 ,每侧约有 1 0～ 1 5个细胞呈强NOS阳性反应 ,其突起也呈强阳性反应 ,并经脑足神经索进入足神经节的中央纤维网中 ;足神经节内只有 2个细胞呈弱阳性反应 ,其突起较短 ,进入足神经节中央纤维网中 ,但足神经节中 ,来自脑神经节阳性细胞和外周神经系统的纤维大多呈NOS阳性反应 ;脏神经节的前内侧部和后外侧部各有一个阳性细胞团 ,其突起分别进入后闭壳肌水管后外套膜神经和脑脏神经索。脏神经节背侧小细胞层以及联系两侧小细胞层的纤维也呈NOS阳性反应。嫁中枢神经系统各神经节中没有发现NOS阳性胞体存在 ;脑神经节、足神经节、侧神经节以及脑 -侧、脑 -足、侧 -脏连索中均有反应程度不同的NOS阳性纤维 ,这些纤维均源于外周神经。与已研究的软体动物比较 ,嫁和前鳃亚纲其它种类一样 ,神经系统中NO作为信息分子可能主要存在于感觉神经。而中国蛤蜊的神经系统中一氧化氮作为信息分子则可能参与更广泛的神经调节过程。

The distribution of nitric oxide synthase(NOS) positive cells and fibers histochemically stained for NADPH diaphorase(a nitric oxide synthase) were studied in the nervous systems of two molluscs Mactra(Mactra) chinensis Philippi (Mollusca,Bivalvia) and Cellana toreuma(Mollusca,Gastropoda).The results indicate:there are about 10-15 NOS positive neurons on each side of the ventromedial cerebral ganglion.The positive processes of these neurons enter the neuropile of the pedal ganglion through the cerebropedal connective.The neuropile of the pedal ganglion has abundant positive fibers from the cerebral ganglion and peripheral pedal nerve.Only a few neurons in the pedal ganglion are had a weakly positive reactive.The processes of these neurons enter the neuropile of the pedal ganglion also.Three groups of positive neurons distribute in the anteromedial,posterola-teral and dorsal small neuron layer of the visceral ganglion.The positive processes of these neurons enter the mantle-siphon nerve,dorsal small neuron layer and cerebral-visceral connective.The dorsal small neurons and the connective fibers between the two sides of the visceral ganglion displayed an NOS positive reactive.There are no NOS positive neurons in the central nerve system of C.toreuma,but positive nerve fibers were widely distributed in the cerebral ganglia,pedal ganglia,pleural ganglia,cerebropedal connective,cerebropleural connective and pleurovisceral connective.The positive fibers in the C.toreuma central nerve system all originate from peripheral nerves.The results of this study indicate that nitric oxide as a messenger molecula may exist mainly in the sensory nerves of C.toreuma,but have a more wider range of neural regulation in the nervous system of M.chinensis.