Ciona intestinalis has a well developed nerve plexus associated with the dorsal strand, as first described by Marco Fedele. The dorsal strand plexus is immunoreactive with antisera against gonadotropin-releasing hormone. Immunoreactivity is seen in the cell bodies, which lie peripherally, and in processes which run throughout the dorsal blood sinus, enter the branchial sac and penetrate the brain via the visceral nerve. The plexus provides a rich innervation of the gonoducts, and processes have been seen in the gonads. The pericardium is not innervated by processes from the plexus and the rectum is poorly innervated, but the full extent of the plexus in the viscera remains uncertain. While this study confirms many of Fedele's observations, it does not support the view that the dorsal strand plexus is equivalent to the vertebrate visceral nervous system.
Author response: The CNS connectome of a tadpole larva of Ciona intestinalis (L.) highlights sidedness in the brain of a chordate sibling
