The relation between tumor cell proliferation and vascularization in differentiated and undifferentiated colon carcinomas in the rat.

Tumor cell proliferation and tumor vascularization were investigated in differentiated and undifferentiated colon carcinomas of the rat. The following results were found: 1, in both tumor types, vascularization is developed equally well; 2, both in the differentiated and in the undifferentiated carcinomas, the number of proliferating tumor cells decreases with increasing distance from the capillaries; at a distance of about 80 microns, there is no longer any noteworthy tumor cell proliferation; 3, the differentiated and undifferentiated carcinomas differ both in the level of the mitosis index and 3H-thymidine labeling index as well as in their local proliferation pattern despite equal vascularization; 4, these differences must be based on factors which are independent of vascularization; they are attributed to proliferation properties which are inherent in the differently differentiated tumor cell populations. It is concluded from this that the actual proliferation behavior of a carcinoma is primarily dependent on the proliferation properties of the tumor cell population.