(a) Intradermal injection of human melanoma cells into xenografted human skin resulted in nodular melanoma growth within the human dermis in a pattern similar to the vertical growth phase of patient melanomas. Arrows indicate the junction between xenograft and mouse skin. (b) High-power view of melanoma tumor nodules growing in the human dermis (D). (c) PAS-D staining revealed anastomosing channels within the intradermal tumor nodules. (d and e) Immunohistochemical examination with CD31 showed negative or weak staining of these anastomosing channels, in contrast to strong staining of human vessels populating the surrounding human dermis at the perimeter of the melanoma nodules. (f and g) Immunofluorescence staining for VE-cadherin, a marker for VM, in the regions of PAS-D-positive, CD31-negative channel formation, showed an identical anastomosing pattern. VE-cadherin stains in red; nuclei in blue.