Growth of malignant tumors relies on development of new vessels from the existing vessels, a process called angiogenesis. Little is known about the pattern of chronic vascular growth in the human germ cell testicular cancer. To shed light on this topic, we injected human CRL-2073 testicular cancer cells or saline (sham treated mice) into the testes of SCID-mice and studied the growth of the tumor's vasculature using intravital video microscopy (IVM) on days 7, 14, 21, 28 and 37 after injection. On each day, 4 mice were studied. To better identify microvessels, fluorescein isothiocyanate-dextran (FITC) was injected i.v. prior to IVM. After IVM, one testis was cast with Mercox and studied in a scanning electron microscope (SEM), the other was used for histology. IVM images were transferred to the computer and analyzed using the Lucia morphometry software.