title: The two nerve rings of the hypostomal nervous system of Hydra vulgaris-an immunohistochemical analysis.
abstract: In Hydra vulgaris, physiological and pharmacological evidence exists for a hypostomal circumferential neuro-effector pathway that initiates ectodermal pacemaker activity at tentacular-hypostomal loci coordinating body and tentacle contractions. Here, we describe an ectodermal nerve ring that runs below and between the tentacles, and an anti-GABABreceptor antibody-labeled ring coincident with it. The location of this ring is consistent with the physiology of the hypostomal pacemaker systems of hydra. We also describe a distally located, ectodermal ring of nerve fibers that is not associated with anti-GABABreceptor antibody labeling. The neurites and cell bodies of sensory cells contribute to both rings. The location of the distal ring and its sensory cell neurites suggests an involvement in the behavior of the mouth. Between the two rings is a network of anastomosing sensory and ganglion cell bodies and their neurites. Phase contrast, darkfield, and antibody-labeled images reveal that the mouth of hydra comprises five or six epithelial folds whose endoderm extensively labels with anti-GABABreceptor antibody, suggesting that endodermal metabotrobic GABA receptors are also involved in regulating mouth behavior.
authors.affiliation: Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA.|Interdisciplinary Neurosciences Program, University of Rhode Island, Kingston, RI 02881, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Hufnagel
authors.affiliation: Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA. gkass-simon@uri.edu.|Interdisciplinary Neurosciences Program, University of Rhode Island, Kingston, RI 02881, USA. gkass-simon@uri.edu.
authors.forename: G
authors.initials: G
authors.lastname: Kass-Simon
mesh_terms: D000825:Animal Structures / Q000166:cytology / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000378:metabolism; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000378:metabolism; D006829:Hydra / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D009412:Nerve Fibers / Q000378:metabolism; D009420:Nervous System / Q000166:cytology / Q000378:metabolism*; D018080:Receptors, GABA-B; D014404:Tubulin / Q000378:metabolism
chemical_list: D000906:Antibodies; D018080:Receptors, GABA-B; D014404:Tubulin
keywords: Feeding behavior; GABAB; Neuroreceptors; Pacemakers; Sensory cells