Fine structure of neurons within the pars intercerebralis of the cockroach, Blaberus craniifer

Abstract

This study is an effort to discover what submicroscopic changes occur in seemingly homologous neurosecretory cells in the anterior pars intercerebralis of a species of cockroach during the final molt. The ergastoplasm is most well organized in closely packed perinuclear rings in mature nymphs 21 days after molt and in an adult female 3 days after molt. The cytomembranes and cytoplasmic matrix were most disrupted in nymphs about to molt and in an adult female 12 hours after molt. Reconstitution of the endoplasmic reticulum seems to be very rapid following molt. The Golgi apparatus shows few changes under any conditions studied. However, dense intracisternal material, presumably a direct precursor of the neurosecretory granules commonly found associated with the Golgi zones, is found only in the 3-day adult female. This observation indicates that the young adult cockroach may be a useful source of information on neurosecretory phenomena. The neurosecretory cells share with other neurons another class of inclusion (“lamellar bodies”) which is not neurosecretion in the strict sense, but does show some change in size, number, and internal complexity during the molting period. Comparison with organelles and with similar inclusions in neurons of other animals suggests a relationship with degenerating mitochondria and with the lipofuscin bodies of vertebrates. It is concluded that molt is a time of complex organelle degeneration and rapid reconstitution of structure and function in some neurosecretory cells of cockroaches.