part_of part of part of contained in material entity muscle cell head region visual system cell guidepost cell Planarian_Anatomy https://orcid.org/0000-0003-2569-1939 | https://orcid.org/0000-0002-7535-4407 A cell present near the brain and eye where photoreceptor axons form a bundle projecting out from the eye that are near axon choice points. Guidepost cells are positive for Arrestin, notum, fz5/8-4+, 6G10, and low levels of troponin, tropomyosin, colF-2 and mp-1.