Abstract

The distribution and density of adrenergic neurons in the normal and denervated cat nictitating membrane have been studied by the histochemical fluorescence procedure of Falck and Owman (Acta Univ. Lundensis (II) 7: 1-23, 1965). Normal cat nictitating membranes exhibit a dense network of pale green, intensely fluorescent fibers which is restricted to the smooth muscle of the tissue and to the blood vessel walls. There is no detectable fluorescence in the nictitating membrane 4 days after denervation. Thorough and systematic examination of nictitating membranes 23, 25 and 28 days after denervation failed to reveal the presence of fluorescent fibers. Twenty-eight days after denervation, administration of α-methyl-norepinephrine to the cat prior to the removal of the nictitating membrane did not result in the visualization of fluorescent fibers. It thus appears that upto 4 weeks after excision of the superior cervical ganglion, no regeneration of adrenergicfibers into the nictitating membrane has occurred. These results are consistent with the observations that a progressive loss of norepinephrine from the nictitating membrane occurs for at least 2 months after denervation and that denervation supersensitivity increases progressively for at least 28 days after denervation.