Projection of statocyst sensory neurons associated with crescent hairs in the crayfish Procambarus clarkii girard.

The central projection of statocyst sensory neurons associated with the crescent hairs of the crayfish Procambarus clarkii was investigated. Cobalt fills of statocyst nerves revealed that they entered the brain as the two discrete fiber bundles and terminated in different portions of the brain. One terminates in the ipsilateral half of the brain and the other in the contralateral half. The later was further subdivided into two discrete components. The relationship between the location of statocyst receptors in the different regions of the crescent and their central projection pattern was investigated by the extracellular cobalt marking method. The results showed that the two fiber bundles, which projected to the ipsilateral and contralateral halves of the brain respectively, originated from different regions of the crescent. Ipsilaterally projecting neurons had their origin mainly in the posterior hairs of the sensory crescent whereas contralaterally projecting ones in the anterior hairs of the sensory crescent.