Ultrastructural evidence for peptidergic innervation of the apical region of frog olfactory epithelium
Ultrastructural examination of the region near the olfactory epithelial surface of leopard frogs revealed the presence of nerve terminals just proximal to the zonula adherens between adjacent sustentacular cells, and between sustentacular cells and olfactory receptor neurons. Terminal varicosities, located about 20 nm from sustentacular cell membranes, contained numerous large-diameter dense-cored vesicles, small-diameter agranular vesicles, and mitochondria. On the basis of ultrastructural characteristics, they are identified as peptidergic sensory terminals.
Zielinski, Barbara S.; Getchell, Marilyn L.; and Getchell, Thomas V., "Ultrastructural evidence for peptidergic innervation of the apical region of frog olfactory epithelium" (1989). Brain Research, 492, 1–2, 361-365.