Effect of ten different target tissues on nerve fibre outgrowth from rat sympathetic ganglia in organotypic co-cultures.

Sympathetic thoracic chain ganglia of 3-day-old rats were cultured in collagen gel medium for 24 hours together with explants from heart atrium, liver, kidney, cornea, iris, lung, adrenal cortex, adrenal medulla, skeletal muscle, or vas deferens. The extent of nerve fibre growth was estimated by counting the number of fibres crossing each arc of a sector drawn in the ocular. The various tissues stimulated nerve fibre growth to distinctly different extents. The increase in the nerve fibre outgrowth induced by atrium and iris was statistically highly significant. Kidney, liver, vas deferens, lung, and adrenal cortex had, in that order, a decreasingly stimulatory influence on sympathetic chain ganglia. Yet they all caused a significant increase in nerve fibre growth. Skeletal muscle, cornea and adrenal medulla had no stimulatory effect. Since the significant effects of the tissue explants were abolished by antiserum to nerve growth factor (NGF), it is concluded that the observed effects were due to NGF produced by the explants. The only exception was vas deferens, the stimulatory action of which proved to be partially NGF-independent.