Comparison of human and porcine umbilical cords. While differing in overall diameter, cross sections of miniature swine (A) and human (B) umbilical cord tissue share anatomic similarities (hematoxylin and eosin stain; scale bar = 1 mm). In addition, immunohistochemical staining for CD90 (red) and vimentin (green) expression, markers that identify both pig and human UTCs in culture, indicates that these cells are found in abundance and share phenotypic similarity (DAPI: nuclear counterstain, IHC; scale bar represents 100 μm). See “Immunocytochemistry” for image acquisition information.