Fine structure of the retinal rods and cones in the domestic pig.

The structure of the retinal photoreceptors of the domestic pig has been studied by both light and electron microscopy. In this species the photoreceptors can be traditionally and adequately differentiated into rods and cones, with rods being the more numerous. Rods are long, slender cells, while cones are shorter and stouter. Both rods and cones consist of an outer segment, a connecting cilium, an inner segment, a nuclear region and a synaptic process leading to a synaptic ending. Differences are noted between rods and cones for the various regions of these cells. What are presumed to be the displaced cell bodies of both rods and horizontal cells are often noted within the outer plexiform layer of this species.