Intrinsic Innervation of the Human Placenta

Abstract

THE placenta and foetal membranes are usually described as being devoid of neural elements^1,2. In other descriptions, the possibility of an innervation is not considered^3,4. Nevertheless, reports of the presence of nerve elements in these foetal tissues continue to appear in the European literature^5–7. Improvements in techniques for the examination of neural elements in fresh tissue have allowed us to re-investigate this apparent contradiction. Samples of fresh placentas and their attached foetal membranes were removed by sharp dissection for staining in methylene blue within 30 min of delivery. The excised pieces (about 2 mm thick) were stained and prepared for examination as whole mounts with the use of an immersion technique⁸. In this method, fresh tissues are immersed in methylene blue solution, fixed in chilled ammonium molybdate solution, washed with water, rinsed in 95 per cent alcohol, and dehydrated in absolute alcohol. The dehydrated tissues are cleared in xylene and benzyl benzoate and stored and examined in the latter fluid.