Nerve Distribution in Human Fetal Appendages, Particularly in the Umbilical Cord

Abstract

The placenta and umbilical cord are conceived in general to have no nerves, while their blood vessels are experimentally known to contract or dilate in response to certain drugs or specific conditions. To explain this relation, the authors, in the present study, examined the presence of nerve fibers in the human umbilical cord and placenta by using Seto's silver impregnation staining. The results were: (1) Nerve fibers, stained by the silver impregnation, were found in the umbilical cord, existing in the form of nerve bundles mainly in the Wharton's jelly. Fine fibrils that diverged from the bundles partly formed a- terminal reticulum or freely ended in the vascular wall. (2) The nerve was amyelic, morphologically classified as the vegetative nerves. (3) The nerves in the umbilical cord were present limitedly in the 1/3 to 1/4 range proximal to the fetus, which indicated that they had probably extended by way of the umbilical ring from the fetus. (4) No nerve fibers were found in the placenta.