REVASCULARIZATION OF HUMAN PARATHYROID TISSUE TRANSPLANTED TO ATHYMICMICE

The revascularisation process of transplanted human normal, hyperplast ic and adenomatous parathyroid tissue was analysed at 2 and 4 days and 1, 2, 4, 7 and 12 weeks after transplantation to athymic mice. The tr ansplants were examined by light and electron microscopy, immunohistoc hemistry and autoradiography. Vessels were detected by monoclonal anti bodies specific for mouse and human endothelial cells. Immunohistochem istry demonstrated ingrowth of vessels from the host into the transpla nt and at one week numerous capillary sprouts were observed in the per ipheral parts of the transplants. During the first week, peak levels o f proliferation (labelling index) were observed in endothelial cells a nd capsular fibroblasts, and the proliferative capacity of endothelial cells was most pronounced in adenoma transplants. Fenestrated capilla ries were observed in hyperplastic and adenomatous transplants, but no t in transplants of normal tissue. In conclusion, revascularisation of transplanted human parathyroid tissue is enabled by ingrowth of vesse ls from the host into the transplant. The proliferative capacity of en dothelial cells is higher and the process of maturation is faster in h yperplastic and adenomatous tissue compared to normal tissue.