Absence of Adrenergic Nerves in the Human Placenta

Abstract

ALTHOUGH it is generally accepted that nervous tissue is absent in the human placenta and umbilical cord¹, the presence or absence of nerves has long been a controversy. In a review of the literature to 1943, Spivack² surveyed the reports of an innervation, which was variously described as adrenergic, cholinergic, myelinated, non-myelinated and a diffuse anastomosing network. Spivack, however, pointed out the difficulties of interpreting results with conventional neurological stains and described work with silver and methylene blue staining which gave no evidence of a nervous apparatus. There have been several recent reports of neuronal components in these tissues^3,5. Jacobson et al.^6,7 presented evidence of nerves in the placentae of human and other primate species. Using a modified methylene blue technique^8,9, they suggested that this innervation was intrinsic, with groups of cell bodies within the placenta, nerve bundles in the villi and fine fibres about vessels.