Fig. 2

Vascularization and connective tissue column formation in C38 liver metastases. a Scanning electron microscopic micrograph of the vasculature of an experimental colorectal carcinoma metastasis in the liver after corrosion casting. On the upper-right side can normal structure of the sinusoidal system be observed (arrowheads). Sinusoidal lakes (asterisk) developed by fusion of the sinusoids can be observed close to the surface of the tumor. Arrows point at vessels supplying the metastasis. These structures correspond to the structure labeled by CD31 on Fig. 2b. Scale bar 100 µm. b The structure of (blood supply-providing) connective tissue columns in liver metastases. CD31-positive vessel (green) is located centrally and surrounded by smooth muscle actin (red)-expressing cells. The structure is surrounded by basement membrane (laminin, blue) deposited by tumor cells. Basement membrane (laminin, blue) of the central vessel can also be observed. Tumor cells (not stained) are located in the black areas. Scale bar 10 µm