Morphological observations of induced lesions of tibial dyschondroplaisa in broiler chicken
2007
Kachi, M.(Niigata Univ., (Japan)) | Sugiyama, T. | Kusuhara, S.
Tibial dyschondroplasia (TD) is a chondrogenic disease in meat-type growing poultry that results in retention of cartilage plug in the growth plate of the proximal tibia. The lesion is characterized by an accumulation of uncalcified cartilage matrix and hypertrophic chondrocytes that prevent endochondral bone formation. In this study, to establish a model system of TD and to understand the pathological process of TD, we induced TD in the 7-day-old chicks by peroral administration with tetramethylthiuram disulfide (thiram), and observed gross anatomical and histological changes in the proximal tibiae. As a result, the cartilage plugs appeared in thiram-treated 10 day-old chicks, and were most frequently observed in the 20-day-old chicks. Histologically, the cartilage plugs were located in the epiphyses and were composed of increased number of hypertrophic chondrocytes. The chondrocytes showed weak activity of lactate dehydrogenase and some of them presented nuclear pyknosis, cytoplasmic condensation, or apoptosis. These lesions were also characterized by a few cartilage canals without blood vessels. These results suggested that TD lesions are ischemic, in which the supply of osteoclasts and osteoblasts via blood vessels and the cartilage matrix calcification are suppressed, leading to the loss of endochondral bone formation. Consequently, hypertrophic chondrocytes are not resorbed and accumulate in the growth plate as TD. This treatment of chick with thiram is also a superior model for TD research.
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