STROMAL DIFFERENTIATION AND ARCHITECTURE OF THE HUMAN UMBILICAL-CORD

In order to assess the characteristics of its stromal cells and the di stribution of extracellular matrix proteins, me investigated, immunohi stochemically and ultrastructurally, term, first and second trimester human umbilical cords. A differential distribution pattern of the vari ous cytoskeletal proteins of stromal cells and extracellular matrix pr oteins was observed in different zones of the stroma, the subamniotic stroma, Wharton's jelly, and the vessels' adventitia. All three zones showed immunoreactivities for collagen types I, III and VI and for bas ement membrane molecules such as collagen type IV, laminin and heparan sulphate proteoglycan. Immunoreactivities for these extracellular mat rix molecules were observed around cleft-like territories (stromal cle fts) in the Warton's jelly which were occupied by homogeneous ground s ubstance but void of collagen fibrils and basal lamina molecules. More over, between the stromal clefts, slender cells were found which immun ohistochemically and ultrastructurally corresponded to various stages of myofibroblastic differentiation. In earlier stages of gestation, st romal cells with a less complex expression pattern prevailed. The stro mal clefts and the contractile cells together might serve as a system regulating the turgor of the cord. (C) 1997 W. B. Saunders Company Ltd .