Characterization of Microvasculature in the Stroma of Human Colorectal Carcinoma: An Immunoelectron Microscopic Study on Factor VIII/von Willebrand Factor

Ultrastructural immunolocalizatlon of factor VIII/von Willebrand factor (vWF) (formerly, factor VIII related antigen) was studied in microvessels in the stroma of human colorectal carcinomas (11 cases), normal mucosa and granulation tissue by the pre-embedding method. In capillaries of the normal mucosa, vWF was localized along the luminal plasma membrane, in scanty rough endoplasmic reticulum (rER), round granules, and Weibel-Palade bodies. In cancer stroma, vWF was localized in well-developed rER, round granules and Weibel-Palade bodies in hypertrophied endothelial cells, in narrow vascular lumen as a cluster, and diffusely in subendothelial space. These microvessels partly resembled newly formed immature capillaries in granulation tissue. But well-developed, immunoreactive rER were observed only in cancer stroma. We have concluded that microvasculature of human colorectal carcinoma is different from that of the normal mucosa in both ultrastructural features and immunolocalization patterns of vWF.