Abstract: In the neurosecretory cells of the caudal neurosecretory system of Megalorama amblycephala, the mitachandria, Golgi compieg, rough endaplasmic reticulum and free ribosomB are weli-developed. The caudal neurosecretary cells and theix axons contain three major types of granules, namely electron-lucent granules,electron-dense and leas eiectron-dense granules.The desmosome can be found occasiorally between unmyeiin.ated nerve fibres in the urophysis. As the gonads develop from stage III to VI，the changes of organellas are not distinct morphologically. But there are significant differences in number and distribution of three Binds of granules. The ultrastuctural changes of caudal neurosectrory sells and neurohemal regions show that the artificially induced spawning can accelerate releasing the secretory materials of electron-dense granolas into the blood capillary.