Neuroanatomy of the retrocerebral complex, in particular the pars intercerebralis and partes laterales in the cockroach Diploptera punctata eschscholtz (Dictyoptera : Blaberidae)

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The retrocerebral complex of the cockroach, Diploptera punctata (Dictyoptera Blaberidae) was studied by means of scanning electron microscopy and rapid retrograde axonal diffusion of NiCl,. The corpora cardiaca (CC) are joined to the brain via nervi corporis cardiaci I, II and III, and to each other via a cardiacal-commissure organ. Corpora allata (CA) are joined to the CC via stout nervi corporis allati I (NCA I) and to the postallatal nerves (PAN) via projections of the CC within the CA sheath. Exposure of the retrocerebral complex, after the NCA I were sectioned, to 500 mM NiCl 2 for 0.5 min resulted in the backfilling of neurons with axons in the CA/CC. A total of 60 somata were observed in the pars intercerebralis (PI) and 25 in the pars lateralis (PL) in each protocerebral hemisphere. When the PAN were backfilled, 20 somata in the PI and 5 in each PL were observed. Thus it is possible that a total of 40 somata in the PI and 20 in the PL on each side of the brain send axons to the CA or beyond.