Innervation of tentacles and small stubs in <i>Lingula anatina</i>.

<p>Z-projections of a portion of the brachium after staining for α-tubulin (cyan) (<b>A, C, D</b>) and FMRFamide (green) (<b>B, E, F</b>). (<b>A</b>) Z-projection of the most ventral slides shows the nerve fiber (ano) along the abfrontal side of the outer tentacles. Some fibers skirt the tentacles (arrowheads), others pass to the brachium base (double arrowheads). (<b>B</b>) FMRFamide-like immunoreactivity in the abfrontal neurites (ano) of the outer tentacles. Groups of FMRFamide-like immunoreactive perikarya (gp) between tentacles are shown. (<b>C</b>) Z-projection of several middle slides of the stack: neurite bundles of tentacles of both rows are visible. (<b>D</b>) Z-projection of the whole stack: neurite bundles of tentacles of both rows and small stabs are visible. (<b>E</b>) Z-projection of the most ventral slides of the stack: FMRFamide-reactive nerve fibers, which pass from a group of perikarya (gp) and innervate small stabs. (<b>E</b>) Z-projection of several middle slides of the stack: the thick abfrontal neurite bundle (ani) of the inner tentacles originates from the group of FMRFamide-like reactive perikarya. Abbreviations: ani, abfrontal neurites of inner tentacles; ano, abfrontal neurites of outer tentacles; fno, frontal neurites of outer tentacles; gp, group of FMRFamide-like immunoreactive perikarya; lani, latero-abfrontal neurites of inner tentacle; lfno, latero-frontal neurites of outer tentacle; shn, short nerves; ssn, neurites of small stubs.