Quantitative differences between sympathetic nerve terminals.

The fluorescence histochemical method for catecholamines shows differences in both innervation density and fluorescence intensity between sympathetic nerve terminals in different organs. Quantitative electron microscopy shows differences in vesicle density in varicosities of nerve terminals in heart, spleen and vas deferens of the rat. The electron-dense core of the small noradrenergic vesicles has a different mean volume and a different core-size distribution in different nerve terminals. The significance of these findings is discussed.