The aim of the present study was to investigate the effects of systemic administration of amylin on the avian tibia using histological, histomorphometrical and biochemical methods. Forty "Super Nick'' laying hens 10 weeks of age were used. The experimental groups were injected subcutaneously in the loose skin at the nape of neck every other day with 75 mu g kg(-1) doses of rat amylin. The morphology of the cells and organic components of bone were studied in standard decalcified preparations at 14, 16, 18 and 20 weeks of age. Cortical bone and tibial growth plate widths were measured from the histological sections. Serum calcium, plasma amylin, parathyroid hormone related peptide (PTHrP) and calcitonin levels were determined at the same ages. Our results suggest that, when administered systemically to laying hens, amylin stimulates the proliferation of chondrocytes and osteoblasts and increases tibial growth plate thickness.