Innervation of luminous glands in the calanoid copepod Euaugaptilus magnus

Abstract

Evidence is presented of direct innervation of the secretory cells of luminous glands in the calanoid copepod Euaugaptilus magnus (Wolfenden, 1904). Synaptic structures are present, characterized by specialized pre- and post-synaptic membranes, clusters of synaptic vesicles and pre-synaptic dense bodies. Only one type of synaptic vesicle is present; this is spherical, clear cored and 30–50 nm in diameter. Similar vesicles at synapses in other Crustacea are thought to contain the neurotransmitter glutamate. Each gland appears to be innervated separately and all four secretory cells of each gland are innervated by the same nerve, giving rise to the possibility that control can be exerted over the firing of individual luminous glands.