Ultrastructural and immunohistochemical studies of Wharton's jelly umbilical cord cells.

In order to determine the significance of Wharton's jelly, the characteristics of these cells were examined by means of electron microscopy and immunohistochemistry. These cells possessed ultrastructural characteristics of both fibroblasts and smooth muscle cells, indicating that they are modified, rather than typical fibroblasts. Immunohistochemically those 'myofibroblasts' stained positive for actin, non-muscle myosin, vimentin and desmin. Staining for muscle myosin was negative, supporting the ultrastructural findings. As our results indicate that these cells can function in both fibrogenesis and cell contraction, we speculate that they may contribute to the elasticity of Wharton's jelly, by synthesizing collagen fibers, and participate in the regulation of umbilical blood flow by virtue of their contractile properties.