Anatomy and electrophysiology of neurons terminating in the corpora allata of the cockroach Diploptera punctata.

Intracellular recording and dye injection were used to study the structure and electrophysiological properties of individual neurons that project to the corpora allata of the cockroach, Diploptera punctata. Neurons in the pars intercerebralis generate long-duration, tetrodotoxin-sensitive action potentials. Dye injection revealed two cell types. One type extends axons to the contralateral nervi corporis cardiaci I, some of which innervate the corpora allata, and another type extends a major axon down each of the circumoesophageal connectives. Neurons in the pars lateralis also generate long-duration action potentials. These neurons extend axons to the ipsilateral nervi corporis cardiaci II, which continue on to terminate in the corpora cardiaca and the corpora allata. Small groups of all the above neuronal types are dye and electrically coupled. Penetration and dye injection into nerve terminals in the corpora allata and corpora cardiaca confirmed the innervation of the corpora allata by neurons located in the pars intercerebralis and pars lateralis and revealed a third class of neurons that have terminals in the corpora allata: intrinsic neurons of the corpora cardiaca.