Axon pathways of the intermediate neurosecretory cells in Culex tarsalis Coquillett (Diptera: Culicidae)

Abstract

The axons of the intermediate neurosecretory cells in the brain of Culex tarsalis Coquillett larvae cross over in the pars intercerebralis, pass ventrolaterally through the protocerebrum, and then pass through the circumoesophageal connectives and the ventral nerve chain as far as the eighth abdominal ganglion. These axons possess branches in the region of juncture of the proto- and deuto-cerebrum, and in the suboesophageal, thoracic, and eighth abdominal ganglia; no branches were visible in the tritocerebrum or abdominal ganglia 1 to 7. The branches appear to terminate within the ganglia, usually near the neuropile boundary. The large ventral neurosecretory axons described in larvae of Culiseta inornata (Williston) by L. Burgess in 1971 are probably the axons of the intermediate neurosecretory cells of that mosquito.