Hypertrophic chondrocytes, which are the terminally differentiated form of chondrocytes, play a key role in endochondral ossification.In order to investigate the functions of hypertrophic chondrocytes during bone development, we generated a new transgenic line expressing Cre recombinase under the control of a 8.2 kb mouse type X collagen gene promoter (CollOal(8.2)-Cre).Microinjection was employed to introduce the 11.5 kb transgenic fragment into 328 oocytes, from which 51 progenies were obtained.Three mice carrying the transgene in genome were identified by PCR genotyping.