Abstract:

The aim of this study was to study the ultrastructure of tibia growth plate in broiler chickens with a thiram (Tetramethylthiuram disulfide)-feeding procedure at the different stages. Seven-day-old AA broiler chickens were fed a regular diet containing thiram 100 mg·kg^－1 for 48 h, then were dissected quickly, and growth plates were fixed in 2.5% glutaric dialdehyde solution in 4 ℃ when they were 8, 9, 13 day-old. The ultrastructure of chondrocyte was observed by transmission electron microscope. The results showed that proliferative chondrocytes were slightly necrotic, increased numbers of swollen mitochondrion appeared electron-dense particles and vesiculated cisternae of the endoplasmic reticulum were in rounding at 8 day-old, and swollen mitochondrion, breaked and dilated cisternae of the endoplasmic reticulum were more severe at 9 day-old; plasmolysis and doubtful apoptotic prehypertrophic chondrocytes were discovered at 8, 9 day-old, moreover, lighten necrotic prehypertrophic chondrocytes with complete cellular structure and increased secretory vacuoles with fine particles of proteoglycans emerged at 13 day-old. In conclusion, both proliferative cells and prehypertrophic chondrocytes of growth plates were damaged by thiram in a short time, especialy to prehypertrophic chondrocytes. We supposed that this changes would influence normal chondrocyte development. It was possible that thiram could disturb the energy metabolism and cellular signal transduction which confused the cell cycle, and resulted in tibial dischondroplasia.