Histological observations on bone and cartilage of growing turtles treated with calcitonin

Abstract

Three varieties of hatching turtles ( Pseudemys scripta elegans, Graptemys kohni, and Chelydra serpentina sepentina) were fed a calcium-dificient diet for periods of 11–19 weeks. Along with adequate controls, some of these were also periodically injected with parathyroid extract (PTE) with or without salmon calcitonin (SCT). PTE treatment resulted in enlarged bone lacume and canaliculi and the matrix was more receptive to basic stains. Simultaneous administration of calcitonin abolished this effect. In all calcitonin-treated animals, the epiphyseal cartilage was much larger and contained mostly large mature chondrocytes. This cartilage remnant was well calcified, as demonstrated in microradiographs. These changes suggest that calcitonin inhibits osteocytic osteolysis in young turtles as well as in birds and mammals. A concomitant inhibition of chondrolysis is also suggested by the persistence of large cartilage remnants.