The term mediale magnozellulare Zone (Formatio reticularis) refers to one of three parts of the reticular formation of the brainstem subdivided longitudinally on the basis of histochemical stains for neurotransmitters and related enzymes, cytoarchitecture, connectivity, and function as well as conventional stains for Nissl substance and myelin. It is located in the brainstem between the mediane Zone (Formatio reticularis) and the laterale parvozellulare Zone (Formatio reticularis). A prominent feature is large neurones with: 1) long horizontally oriented dendrites, and 2) axons that divide into long ascending and descending branches with numerous side branches ( Schiebler-1999 ).