Intimate apposition of the glomus and smooth muscle cells (g-s connection) in the carotid labyrinth of juvenile bullfrogs

Summary

Intimate apposition of the glomus and smooth muscle cells (g-s connection) was found in almost all glomus cells of the carotid labyrinths in juvenile bullfrogs, Rana catesbeiana. There were three types of g-s connection: between thin processes (0.1–0.2 μm in width) without dense-cored vesicles of glomus cells and smooth muscle cells; between thick processes (1.0–1.5 μm in width) with dense-cored vesicles of glomus cells and smooth muscle cells; and between the tonguelike projections of smooth muscle cells and the flat surface of the glomus cell. In some cases, a single glomus cell made g-s connections with several smooth muscle cells. Exocytosis often occurs at the g-s connection. Afferent and efferent synapses were found on the glomus cells with g-s connections. Reciprocal synapses were also observed. On the basis of these findings, the second and third types of g-s connection are presumed to participate in vascular regulation.