Anterograde and retrograde connections of the lamprey dorsomedial telencephalic neuropil (DTN). Biocytin injections were made to the DTN and representative pictures are shown here. A, following dye loading, round or ovoid shaped cells are labeled in AOE vesicles (red arrow). Scale bar: 20 μ B, olfactory sensory neurons with long thin cell bodies are seen in the main olfactory epithelium (red arrow). Scale bar: 20 μm. C, medial glomerular territories are labeled. Scale bar: 100 μm. D, the DTN has a dense population of fibers and a smaller population of coarse thick fibers at the ventral portion, as well as some thick short fibers in the striatum. Scale bar: 200 μm. E, the caudal aspect of the DTN has a sparse population of short fibers, both coarse and thin. Labeled cells are dorsoventrally oriented, located proximate to the DTN (arrow) (F) and visible throughout the entire rostrocaudal extent of the DTN. G, coarse, thick fibers are labeled in the thalamus. Scale bar = 100 um. H, coarse, thick fibers are seen bilaterally in the hypothalamus. Scale bar = 100 um. I, the habenula is densely labeled with thin and thick fibers. aoe: accessory olfactory epithelium; dtn: dorsomedial telencephalic neuropil; glom: glomerular territory; hab: habenula; hyp: hypothalamus; moe: main olfactory epithelium; ob: olfactory bulb; thal: thalamus.