Connectivity in the Sympathetic Nervous System and its Establishment during Development

Abstract

The three elements of the sympathetic nervous system, the preganglionic neurones in the spinal cord, the postganglionic neurones in the paravertebral or prevertebral chains, and the muscular or glandular effector organs in the periphery, become connected during development in a stereotyped and precise manner. The basis of this specificity appears to reside in, firstly, specific patterns of axonal growth resulting in the arrival of the nerve terminals in the vicinity of their targets, secondly, limited branching and growth of collaterals to permit a sampling of local targets, and thirdly, the close range recognition of the cells of appropriate targets. The navigation of axons to their targets is likely to be mediated via the expression of particular molecules within the environment through which the growth cones move, while the establishment of appropriate synapses may involve recognition of other molecules on the cells of the target, for example, those encoding specific rostro-caudal positional information. Particular diurnal rhythms of sympathetic neuronal activity which may identify specific neuronal subpopulations may also be involved in the refinement of collateral projections. Evidence for a tropic influence of the sympathetic nerves on the maturation of the effector organs and their function is discussed. Show more