An Unusual Distribution of Neuronal Nitric Oxide Synthase (nNOS) Neurons in the Porcine Retina Next to the Ora Serrata

The presence of neuronal nitric oxide synthase (nNOS)immunoreactive (IR)/nicotinamide adenine dinucleotide phosphatediaphorase (NADPH-d) positive cells (mainly amacrine cells) is well known in the retina of numerous species [1]. Surprisingly, a unique situation in the distribution of nNOS cells is present in the porcine retina reported here, which was overlooked by a general description of NOS in the porcine eye [2]. Besides this unique finding, the porcine retina is holangiotic and resembles closely that of man but without the formation of a fovea centralis [3-5]. The pig is therefore frequently used as an animal model for ocular research.