The brain, therefore, which is protected by the blood-brain barrier from disturbing and potentially noxious exogenous and endogenous agents circulating in the blood, has to have certain neurohemal regions beyond this barrier, such as the neural lobe and the median eminence (infundibulum), where neurohor­ mones have free access to the blood stream.

Contributions by: M.R. Brown, L.A. Fisher, W.G. Forssmann, W. Gaida, D. Ganten, K. Hermann, W. Hoefke, M.M. Knuepfer, K. Kraft, R.R. Lang, S. Lundin, G. Mancia, M. Schmelz, G. Stock, P. Thoren, T. Unger, A. Weindl