Limitation of splenic growth as studied by heterotopic splenic implants.

Multiple spleens were implanted in the subcutaneous tissue or the peritoneal cavity of inbred rats which had undergone splenectomy. The total weight of regenerated implants was compared to the weight of implanted tissue. The weight of recovered tissue was not a function of implanted spleen mass; rather, it approximated the unit ratio of the animal's own spleen. Those animals receiving more than ten spleens died by days 3-6 postimplantation, probably as a result of massive necrosis that occurred during the process of regeneration. When implants were made in a temporal sequence of two spleens every 3 days, the first set was uniformly successful, whereas regeneration was aborted in subsequent sets of implants. These observations are consistent with the conclusion that certain factors control the total mass of spleen in any one animal.