Innervation of endocrine tissues

Our understanding of neural regulation of endocrine glands is still fragmentary. Studies on neuroendocrine interactions have been hampered in the past by the fact that neuronal and endocrine systems have long been considered to operate independently and through opposite ‘languages’, the nervous system by highly localized release of rapidly inactivated transmitters, evoking a high-speed and short-duration response, the endocrine system, on the other hand, by secreting hormones, which are conveyed to their effector tissues by the blood and maintain their actions for appreciable lengths of time (1). Moreover, focusing at the examination of the link between the neural and the endocrine apparatus at the site of the hypothalamic neurosecretory centers and the lack of adequate methods for the demonstration of morphological and functional relationships between peripheral nerves and endocrine cells have, for a long time, prevented to successfully approach the problem of a direct nervous control of endocrine cells by conventional synaptic transmission.