Fig. 2. Control experiments on sections of a ventral photophore from the hatchetfish Argyropelecus hemigymnus, showing (A) lack of unspecific staining after omission of primary antibody, and specific staining among the photocytes and in the filter cells, with (B) nNOS 31030 and (C) nNOS sc1025. f, filter cell area; p, photocytes. Bars, 50 µm.