title: Complex neural architecture in the diploblastic larva of Clava multicornis (Hydrozoa, Cnidaria).
abstract: The organization of the cnidarian nervous system has been widely documented in polyps and medusae, but little is known about the nervous system of planula larvae, which give rise to adult forms after settling and metamorphosis. We describe histological and cytological features of the nervous system in planulae of the hydrozoan Clava multicornis. These planulae do not swim freely in the water column but rather crawl on the substrate by means of directional, coordinated ciliary movement coupled to lateral muscular bending movements associated with positive phototaxis. Histological analysis shows pronounced anteroposterior regionalization of the planula's nervous system, with different neural cell types highly concentrated at the anterior pole. Transmission electron microscopy of planulae shows the nervous system to be unusually complex, with a large, orderly array of sensory cells at the anterior pole. In the anterior half of the planula, the basiectodermal plexus of neurites forms an extensive orthogonal network, whereas more posteriorly neurites extend longitudinally along the body axis. Additional levels of nervous system complexity are uncovered by neuropeptide-specific immunocytochemistry, which reveals distinct neural subsets having specific molecular phenotypes. Together these observations imply that the nervous system of the planula of Clava multicornis manifests a remarkable level of histological, cytological, and functional organization, the features of which may be reminiscent of those present in early bilaterian animals.
authors: Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, 73100 Lecce, Italy. stefano.piraino@unisalento.it
authors: Stefano
authors: S
authors: Piraino
authors: Giuliana
authors: G
authors: Zega
authors: Cristiano
authors: C
authors: Di Benedetto
authors: Antonella
authors: A
authors: Leone
authors: Alessandro
authors: A
authors: Dell'Anna
authors: Roberta
authors: R
authors: Pennati
authors: Daniela Candia
authors: DC
authors: Carnevali
authors: Volker
authors: V
authors: Schmid
authors: Heinrich
authors: H
authors: Reichert
mesh_terms: D000818:Animals; D003063:Cnidaria / Q000033:anatomy & histology* / Q000254:growth & development* / Q000502:physiology; D007150:Immunohistochemistry; D007814:Larva / Q000033:anatomy & histology* / Q000502:physiology; D008124:Locomotion / Q000502:physiology; D009420:Nervous System / Q000033:anatomy & histology*; D009479:Neuropeptides / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D009479:Neuropeptides