This proposal is a continuation of studies aimed at understanding how appropriate synaptic connections between pre- and postganglionic neurons in the sympathetic nervous system are established during embryonic development. Using histological and electrophysiological techniques, I will examine, in the chick, the developmental events that result in ordered synaptic relations between pre- and postganglionic neurons. These experiments will delineate the time of formation of sympathetic ganglia from the neural crest, the outgrowth of pre- and postganglionic axons and the temporal relationships between these events. In a second group of studies, I will test the ability of growing embryonic axons to find their appropriate targets after experimental manipulations of the environment. These studies will test three hypotheses: 1) Are the projection patterns of preganglionic neurons determined by their segmental origin in the spinal cord or by the tissue environment outside of the spinal cord? 2) are target cues required for the guidance of preganglionic axons? 3) Is segmentally selective innervation of ganglion cells by preganglionic axons based on the segmental origins of pre- and postganglionic neurons in the neuraxis? The proposed experiments will exploit the accessibility of the chick embryo where it is possible to: 1) transplant preganglionic neurons to a novel environment without disrupting their target cells, 2) remove the neural crest cells that give rise to specific sympathetic ganglia prior to their migration and without damage to preganglionic neurons, 3) label both pre- and postganglionic neurons arising from particular segments of the neuraxis and examine the synaptic interactions between labelled cells using a combination of anatomical and intracellular recording methods. These studies will provide new data on the embryonic development of specific synaptic connection in sympathetic ganglia. At the same time, results from these studies are likely to represent general principles that are applicable to the development of the central nervous system.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Neurology B Subcommittee 1 (NEUB)
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University of Pittsburgh
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Yip, J W; Yip, Y P; Capriotti, C (1998) Segmental specificity of chick sympathetic preganglionic projections is influenced by preganglionic neurons from neighboring spinal cord segments. J Neurosci 18:10473-80
Yip, J W; Yip, Y P; Capriotti, C (1998) Specific projections of sympathetic preganglionic neurons are not intrinsically determined by segmental origins of their cell bodies. J Neurobiol 35:371-8
Yip, J W (1996) Specificity of sympathetic preganglionic projections in the chick is influenced by the somitic mesoderm. J Neurosci 16:612-20
Spence, M S; Yip, J; Erickson, C A (1996) The dorsal neural tube organizes the dermamyotome and induces axial myocytes in the avian embryo. Development 122:231-41
Yip, J W; Yip, Y P; Capriotti, C (1995) The expression, origin and function of tenascin during peripheral nerve formation in the chick. Brain Res Dev Brain Res 86:297-310
Halfter, W; Yip, Y P; Yip, J W (1994) Axonin 1 is expressed primarily in subclasses of avian sensory neurons during outgrowth. Brain Res Dev Brain Res 78:87-101
Yip, J W; Yip, Y P (1992) Laminin--developmental expression and role in axonal outgrowth in the peripheral nervous system of the chick. Brain Res Dev Brain Res 68:23-33
Yip, J W; Yip, Y P (1990) Changes in fibronectin distribution in the developing peripheral nervous system of the chick. Brain Res Dev Brain Res 51:11-8
Yip, J W (1990) Identification of location and timing of guidance cues in sympathetic preganglionic axons of the chick. J Neurosci 10:2476-84