Arterial walls as cephalic neurohemal organs in Lithobius forficatus L. (Myriapoda Chilopoda).

Neurosecretory axon sections of the cephalic arterial walls (aorta and antennal arteries) of the centipede, Lithobius forficatus, are described. An ultrastructural study showed that these sections can be differentiated according to the form, size and electron-opacity of the secretory granules they contain. However, it is not easy to correlate these granules with those observed in the protocerebral neurosecretory cells. Various experiments (cerebral electrostimulation or electrocoagulation, and antennectomy) showed that part of the secretory products originate in the pars intercerebralis secretory cells. Although the cephalic arterial walls are neurohemal organs, certain axons extend beyond the areas investigated and the location of their endings remain unknown.