RESUMEN
Objective:To investigate hypoxia location in condylar cartilage in the early growth stage of rats.Methods:40 Sprague-Dawley rats were breastfed from 1 4 d to 21 d of age.1 0 rats were sacrificed at 1 2,24,48 and 96 h respectively after initiation of normal food at 21 d of age.The rats were administered pimonidazole hydrochloride (HP-1 )at a dose of 60 mg/kg by intraperitoneal injection 2 h before sacrifice.The expression of HP-1 in the whole condylar cartilage was detected by immunohistochemical staining.Results:HP-1 was mainly expressed in the chondrocytes of the fibrous and proliferative layer of cartilage,primarily concentrated in the weight-bearing area of joint-anterior aspect of the condyle and posterior aspect of the articular eminence at all time points.The highest expres-sion was observed at 24 h after initiation of normal food (P <0.01 ).Conclusion:In the early growth stage of rats,dietary loading may directly induce hypoxia in uper layer of condylar cartilage,the hyoxia level may change with time of dietary loading.