Fig. 1

A paraffin embedded cross-section of the human umbilical cord stained with hematoxylin and eosin. Shows an outer amniotic epithelium and three vessels contained within Wharton’s Jelly (WJ), which extend from the tunica media of the vessels to the amniotic epithelium. Wharton’s Jelly is denser in the perivascular zones, due to an increase in both cells and matrix, and measures 350–1550 microns deep in this sample (as marked). The paucity of staining in areas beyond the perivascular zones is, in part, due to the presence of clefts (visible when the image is enlarged) in the Intermediate WJ. The perivascular regions are separated by narrow regions of intervascular jelly that also contains clefts. The asterisks mark artifacts of preparation. Total Width = 15 mm