The Effect of Somatotropin and Hypergravity on Weight Bearing Epiphyses of Cockerels

Somatotropin (STH) administered to earth gravity birds (1 g) stimulated the mean growth in height of the articular cartilage layer of the distal tibial epiphyses (DTE) and of the resting and proliferating layers of the proximal epiphyses of os tarsometatarsus (PE-TMT). However, it inhibited growth in height of the calcified cartilage zone of both epiphyses. Hypergravity control animals (2 g) showed a decreased growth in mean height of proliferating, maturing and calcified cartilage zones of the DTE as well as in the resting and calcified cartilage of the PE-TMT. Hypergravity (2 g) plus STH decreased mean height of articular cartilage zones of the DTE while increasing this parameter within the PE-TMT. The growth in height of maturing cartilage layer of the DTE and of the calcified cartilage zone of the PE-TMT was significantly decreased by administration of the hormone under hypergravity conditions. With the exception of the articular cartilage layer of STH treated 2 g animals the mean growth in width of all cartilage zones of the DTE was significantly decreased by the hypergravity state regardless of whether the animal received somatotropin or the acetic acid suspension media (0.06M CH3 COOH). STH administered to earth gravity animals significantly increased the mean growth in width of all but the articular cartilage layer of the PE-TMT. The same cartilage zones of this epiphysis showed a significant decrease in width following administration of the hormone to animals maintained under hypergravity conditions. OHIO J. SCI. 82(5): 260, 1982