Extravesicular noradrenaline in developing peripheral adrenergic nerves.

Using a fluorescence technique numerous developing noradrenergic nerve terminals were observed in the muscle coat of the rat ductus deferens between 2 and 6 days postpartum. In the electron microscope similar developing nerve terminals possessed an extensive system of tubular endoplasmic reticulum but did not contain the small dense cored vesicles characteristic of mature noradrenergic nerve terminals. Thus the tubular reticulum is proposed as an alternative storage site for noradrenaline in developing adrenergic nerves.