[Autotransplantation of cryopreserved thyroid tissue in dogs]

According to literature data autotransplantation of thyroid tissue for postoperative hypothyroidism remain controversial in the clinical praxis. The aim of this study was to examine the possibility of autotransplantation of cryopreserved (196 degrees C) thyroid tissue pieces in the sternocleidomastoid muscles and in the "apron" formed by the flaps of the greater omentum, and to evaluate their function postoperatively in dogs. Twelve adult mongrel dogs were used in the study. Total thyroidectomy was carried out in all animals. The removed thyroid lobes were cut into 3-4 mm pieces and cryopreserved to -196 degrees C. The cryopreserved thyroid tissue pieces were inserted in the sternocleidomastoid muscle and into the greater omentum. Determination of T3 and T4 levels was carried out pre- and postoperatively. Before sacrificing the surviving animals, total body scans were performed using J131 isotope to assess the function and position of autotransplants. The isotope activity of transplants from the sacrificed animals was evaluated quantitatively and their structures studied histologically. The starting values of T3 and T4 levels of animals were between 0.5 and 0.62 mmol/l and between 10.4 and 14.3 mmol/l respectively. On the 4-6th postoperative days the T3 and T4 levels of all surviving animals decreased close to zero, but from the 7-8th days they gradually increased and in weeks 3-4 reached their starting values. Isotope scans of both the sternocleidomastoid region and the greater omentum showed a significant rise in activity, which was highly different from that of surrounding tissues. Quantitative data obtained by the ROI technique correlated with values obtained after removal of the labelled tissues. The presence of thyroid tissue in the labelled ones was histologically justified. The results show that is possible to preserve the function of cryopreserved thyroid segments from totally thyroidectomized dogs by autotransplanting the segments into the muscles of the neck or into the omentum.