Abstract
Extract: The hearts of ten fetal lambs with gestational ages ranging from 75 days to term (150 days) and of two neonatal lambs were studied by the Falck-Owman mono-amine fluorescence technique to determine the pattern of development of the sympathetic nervous system. At 75–85 days of gestation, no sympathetic fibers are present in the heart, but brightly fluorescent dopamine-containing cells are diffusely scattered throughout the myocardium. Between 75–85 and 100–110 days, large nerve trunks begin to grow in along the coronary arteries and small branches are first distributed to the coronary arteries and later to the myocardium. There is continued growth of sympathetic fibres and, by term, an extensive network exists that supplies a large number of myocardial cells. Some growth occurs after birth, and continued innervation probably persists for several weeks. These findings are helpful in explaining the physiological observations of increasing autonomic activity in the circulation of the fetal lamb, and they suggest that growth of myocardial sympathetic nerves is one of the final steps in development of cardiovascular control.
Speculation: The innervation of the myocardium by sympathetic fibers is incomplete before birth in the lamb. If the same pattern of development is present in the human fetus and infant, it is very likely that the circulation of the premature infant lacks the ability to respond to stress through sympathetic stimulation.
Similar content being viewed by others
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lebowitz, E., Novick, J. & Rudolph, A. Development of Myocardial Sympathetic Innervation in the Fetal Lamb. Pediatr Res 6, 887–893 (1972). https://doi.org/10.1203/00006450-197212000-00006
Issue Date:
DOI: https://doi.org/10.1203/00006450-197212000-00006
Keywords
This article is cited by
-
Anaesthesia for the neonate
Canadian Journal of Anaesthesia (1991)
-
Neural control of renal hemodynamics and function during development
Pediatric Nephrology (1990)
-
Changes of the cardiovascular system during the perinatal period
European Journal of Pediatrics (1987)