Influence of age on the permanence of subcutaneous autografts of the spleen in rabbits

Abstract

We have removed the spleen and auto transplanted in 49 rabbits, varying in age from 26 days to over two years.

The method consists of introducing a small fragment of spleen, roughly 2-3 mm. in diameter, beneath the subcutaneous fascia of the abdomen, through a skin incision which is then closed by suture. These transplants have been subjected to direct examination at approximately monthly intervals to check their taking, growth or absorption. All have taken, except for three instances and these failures were due to infection. The most striking observation was the rapid growth of the grafts in the young rabbits from one to three months old and the lack of growth in the one- and two-year-old rabbits, some of which have undergone complete absorption in three months, as shown by histological examination. On the other hand, none of the transplants in rabbits less than five months old have shown any tendency to undergo absorption and histological examination shows regeneration of the major splenic elements into normal looking, encapsulated, highly vascular little spleens.

We have not been able to complete the series, with rabbits of known ages, between the period of sexual maturity (fifth month) and one year. The marked growth and activity of the transplants in young rabbits as compared with the lack of growth and tendency to absorption in old rabbits may be a part of the normal growth of the animal. In favor of this view is the fact that further growth of the transplants has not been observed after adolescence. There are no reports of differences in the systemic effects of splenectomy relative to age, although there is some evidence from histological studies that a blood-forming function is present in early life and absent in adults.