Effect of intrauterine thymectomy on granulation tissue formation. An experimental study.

Intrauterine thymectomy was successfully performed on 9 guinea pig foetuses at the gestational age of 36-48 days. This resulted in a significant suppression of the phytohemagglutinin (PHA) response of the whole blood lymphocytes at the age of 3 mth. The in utero-thymectomized guinea pigs and their littermate non-thymectomized controls were operated on by making 4 symmetrical dorsal skin incisions and by subcutaneously implanting 8 standardized pieces of viscose cellulose sponge. On the 1st, 3rd, 5th and 10th days the tensile strength of the wounds was determined and the implants were analysed histologically and enzymehistochemically. At the time of incipient fibroplasia on the 5th post-operative day, the tensile strength of the wounds, the number of fibroblasts and the activities of aminopeptidase and succinate dehydrogenase were clearly less in the guinea pigs which had been thymectomized in utero. These findings indicate that adequate thymic function was necessary for normal fibroblast proliferation, since intrauterine thymectomy led to a temporary delay in the beginning of the fibroblastic phase in wound healing.