Selective denervation and specific reactions for adrenergic and acetylcholinesterase (AChE)-containing nerve fibers demonstrate that the dilator pupillae in the cat is supplied by numerous parasympathetic fibers in addition to the wellknown sympathetic ones. The adrenergic fibers do not contain measurable quantities of AChE.
Ehinger B. Double Innervation of the Feline Iris Dilator. Arch Ophthalmol. 1967;77(4):541-545. doi:10.1001/archopht.1967.00980020543019