Immunohistochemical detection of parathyroid hormone-related peptide, Indian hedgehog, and patched in the process of endochondral ossification in thehuman

Parathyroid hormone-related peptide (PTHrP), Indian hedgehog (Ihh), and pat ched (Ptc; a receptor for Ihh) were immunolocalized in tissue undergoing en dochondral ossification in the human. PTHrP, Ihh, and Ptc were immunolocali zed in prehypertrophic and hypertrophic chondrocytes in mature cartilage ma trix. PTHrP and Ptc were immunostained in proliferating chondrocytes and pe richondrial cells, whereas Ihh was not. PTHrP, Ihh, and Ptc showed positive immunostaining in osteoblasts in the bone-forming area. In the bone resorp tion site, PTHrP was immunolocalized in osteoclasts, whereas Ihh and Ptc we re not. The present findings indicated that PTHrP, Ihh, and Ptc were associ ated with the process of endochondral ossification, and suggested the possi ble involvement of Ihh and PTHrP signaling in the regulation of proliferati on and hypertrophy of chondrocytes in human chondrogenesis.