Abstract
Shirai 1 and subsequently Murphy 2 have shown that it is possible to transplant successfully heterogenous tumors into the brain where they grow when after subcutaneous transplantation these transplants would have died. Murphy found the lymphocytic reaction in the brain to be lacking and he attributed the success in heterotransplantations to this factor. In the present investigations I determined how normal tissues (thyroid gland) behaved not after heterotransplantation in the brain but after homoiotransplantation, and whether the lymphocytic and connective reactions which are usually very pronounced after transplantation into the subcutaneous tissue were affected by the change in the site of the transplant. We used guinea pigs in these experiments; the transplants were allowed to remain in the host for periods varying between 20 and 120 days. I also compared the results of homoiotransplantation with those of autotransplantation.
I found that autotransplants of the thyroid gland, removed at a period varying between 60 to 120 days following transplantation, had assumed approximately the character of normal untransplanted thyroid gland. There is only the normal amount of stroma present and lymphocytes are lacking. A thin connective tissue capsule may separate the transplant from the surrounding brain tissue in which a slight increase of glia is noticeable.
Homoiotransplants removed at corresponding periods also show living thyroid tissue and in particular a number of well preserved acini; however, some important differences exist between such homoiotransplants and autotransplants. In the former the preserved tissue is much smaller in amount than in autotransplants; furthermore, in the homoiotransplants the acini are more irregular in shape and size and only some of them contain colloid. The gland tissue is traversed by thick bands of dense fibrous tissue which radiate from a central core of hyaline connective tissue.
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