Histological and histochemical studies of the secretory components of the salamander olfactory mucosa: Effects of isoproterenol and olfactory nerve section

Abstract

Secretory compoenets of the salamander olfactory mucosa, sustentacular cells (SC), and Bowman's glands (BG), were examined histologically and histochemically. In the aquatic larval salamander, SC in sensory grooves contained secretory granules; the submucosa contained a single layer of homogeneous, ductless glands. In the land‐dwelling adult salamander, SC spanning a flat epithelial sheet contained vesicles. Subjacent to the epithelium in both dorsal and ventral mucosae lay BG whose ducts opened at the surface of the epithelium. In the ventral mucosa, two additional layers of olfactory glands (OG) lying below the BG were identified; ducts were not observed in association with the OG. The β‐adrenergic agonist isoproterenol caused depletion of secretory granules from BG and OG of larval, young, and adult salamanders but had no discernible effect on SC. Histochemical techniques (Alcianblue at pH 2.5 and pH 1.0, high‐iron diamine, and the periodic acid‐Schiff reaction) demonstrated that SC contained neutral, acidic, and small amounts of sulfated mucopolysaccharides (MPS). BG and OG contained only neutral MPS. In contrast, glands under adjacent respiratory epithelium contained both acidic and sulfated MPS. Unilateral olfactory nerve section (ONX) caused changes in the histochemical reactivity of acidic and sulfated MPS in SC on the ipsilateral and later on the contralateral side. Neutral MPS staining became enhanced first in the OG that lay under the BG, then in BG cells, and later in the deepest OG layer. Ipsilateral changes preceded contralateral ones. At 24 days post‐ONX, some acinar cells in the deep OG contained acidic but not sulfated MPS.