The injury response of the neurones of Periplaneta Americana.

Bilateral pairs of specific neurones in the metathoracic ganglion of the cockroach were used to study the ultrastructural changes which follow axon injury. The appearance of these matched pairs of cells was compared three days after the axons on one side of the ganglion only had been severed. The control or uninjured cell body appeared normal, but changes were observed in the neurones whose axon had been cut. These changes included a general increase in the number of ribosomes throughout the cytoplasm, dilatation of the cisternae of the endoplasmic reticulum and a reduction in size of the Golgi bodies. No ultrastructural features were seen which could correspond to the perinuclear ring of RNA observed histochemically with the light microscope. The possible nature of this RNA is discussed.