Regional differences in the growth of skin transplants.

We have previously reported that marked differences exist in the relative growth rate of tumors transplanted i.d. or s.c. into different regions of the mouse trunk. The present experiments were undertaken to determine whether or not these regional differences applied uniquely to tumor tissue or whether or not there existed a more basic underlying principle influencing normal tissue growth as well. As a test system we used skin transplants between histocompatible C57BL/6J and C57BL/6-c2J mice. Grafts were placed middorsally in the thoracic or lumbar region and compared for rate of healing in, skin retraction, growth, and hair formation. A marked differential in the establishment and growth of skin grafts was seen: anteriorly placed skin transplants uniformly resulted in larger grafts than did similar transplants placed more posteriorly. Our experiments suggest that there are basic physiologically differences between the more anterior and posterior regions of the trunk that are reflected in the relative growth and maintenance of tissue transplants. As yet we have no clear indication of what factors contribute to this anteroposterior differential.