Neuronal pathways from the dorsal ocelli of the house cricket, Acheta domesticus.

Each ocellar nerve in the house cricket Acheta domesticus contains giant nerve fibers of 10--15 mum diameter, characterized in Golgi-Cox preparations by a single row of short collaterals which runs along nearly the entire length of a fiber. Numerous long collaterals are given off by thin fibers in the ocellar nerve; medium-size fibers give off relatively few collaterals. The lateral ocellar tracts extend posteriorly through the dorsal protocerebrum, crossing the protocerebral bridge dorsally. The smaller median ocellar tract runs more ventrally through the pars intercerebralis; posterior to the bridge its fibers turn out toward the lateral nerves. Golgi and cobalt preparations reveal branching of giant and medium-size ocellar fibers posterior to the bridge at two levels, forming bilateral regions of ocellar neuropile. No ocellar processes appear to be given off to the corpora pedunculata, central body, nervi corporis cardiaci, antennal lobes, or circumesophageal connectives; it is uncertain whether ocellar collaterals extend into the protocerebral bridge or optic lobes. Cell bodies of giant and medium-sized fibers are located in the pars intercerebralis.