Segment-specific pattern of sympathetic preganglionic projections in the chicken embryo spinal cord is altered by retinoids

• Published in: Proceedings of the National Academy of Sciences - PNAS 1998-09, Vol.95 (18), p.10878-10883
• Main Authors: Forehand, C.J. (University of Vermont, Burlington, VT.), Ezerman, E.B, Goldblatt, J.P, Skidmore, D.L, Glover, J.C
• Format: Article
• Language: English
• Subjects: ANIMAL TISSUES; Animals; Anions; AUTONOMIC NERVOUS SYSTEM; Biological Sciences; Cell death; CHEMISTRY; Chick Embryo; Chickens; CHICKS; CHIMIE; DESARROLLO EMBRIONARIO; DEVELOPPEMENT EMBRYONNAIRE; EMBRYONIC DEVELOPMENT; Embryos; Ganglia, Sympathetic - anatomy & histology; Ganglia, Sympathetic - drug effects; Ganglia, Sympathetic - metabolism; IMMUNOHISTOCHEMISTRY; IMMUNOLOGIE; IMMUNOLOGY; INMUNOLOGIA; MEDULA ESPINAL; MOELLE EPINIERE; NERF; NERVES; NERVIOS; Neural crest; NEURONS; POLLITO; POUSSIN; QUIMICA; Receptors; Regional identity; RETINOIC ACID; Retinoids; RETINOL; SISTEMA NERVIOSO AUTONOMO; SPINAL CORD; Spinal Cord - anatomy & histology; Spinal Cord - drug effects; Spinal Cord - metabolism; SYMPATHETIC NERVOUS SYSTEM; SYMPATHETIC PREGANGLIONIC NEURONS; SYSTEME NERVEUX AUTONOME; TEJIDOS ANIMALES; TISSU ANIMAL; Tretinoin - antagonists & inhibitors; Tretinoin - metabolism; Tretinoin - pharmacology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.95.18.10878

Sympathetic preganglionic neurons exhibit segment-specific projections. Preganglionic neurons located in rostral spinal segments project rostrally within the sympathetic chain, those located in caudal spinal segments project caudally, and those in midthoracic segments project either rostrally or caudally in segmentally graded proportions. Moreover, rostrally and caudally projecting preganglionic neurons are skewed toward the rostral and caudal regions respectively, of each midthoracic segment. The mechanisms that establish these segment-specific projections are unknown. Here we show that experimental manipulation of retinoid signaling in the chicken embryo alters the segment-specific pattern of sympathetic preganglionic projections and that this effect is mediated by the somitic mesoderm. Application of exogenous retinoic acid to a single rostral thoracic somite decreases the number of rostrally projecting preganglionic neurons at that level. Conversely, disrupting endogenous synthesis of retinoic acid in a single caudal thoracic somite increases the number of rostrally projecting preganglionic neurons at that level. The number of caudally projecting neurons does not change in either case, indicating that the effect is specific for rostrally projecting preganglionic neurons. These results indicate that the sizes of the rostrally and caudally projecting populations may be independently regulated by different factors. Opposing gradients of such factors along the longitudinal axis of the thoracic region of the embryo could be sufficient, in combination, to determine the segment-specific identity of preganglionic projections