VASCULAR CONTROL MECHANISMS IN PENILE ERECTION - PHYLOGENY AND THE INEVITABILITY OF MULTIPLE AND OVERLAPPING SYSTEMS

A co-ordinated series of vascular events underlie the generation of a penile erection. The control and regulation of this simple event is, i n fact, a complex of interactions occurring at multiple levels. Many o f these individual pathways and responses have been studied extensivel y. The understanding of the necessity for the integration between the individual pathways into a complex of series and parallel coupled mech anisms provides a rationale for the development of a framework of mult iple and overlapping systems. This paper sets out some of the principl es of integrated and balanced control of vasodilation and vasoconstric tion in the penis. In addition, the role of growth induction and regre ssion and the importance of time as a factor in studying penile struct ure and function is discussed.