title: Effects of fracture trauma, estrone treatment, and 2-G environment on the epiphyseal cartilage zones of developing avian radii.
abstract: Female birds subjected to closed fracture of the right radius at 2 weeks post-hatching were allowed to heal for 14 d at either earth gravity (1 G) or a 2-G hypergravity state, with saline-injected controls and 0.2- and 0.4-mg estrone (estrogen) treated groups. Animals were sacrificed following the last injection and radii were routinely processed histologically for micrometer measurements of the mid-coronal height and width of the cartilage zones of the proximal and distal epiphyses. Proximal epiphyses of estrone-treated, normo-gravity chicks showed a decreased growth in height of the articular, proliferating, and hypertrophic cartilage zones and an increased interstitial growth of the hypertrophic and calcified layers of estrone-treated, 2-G animals. Growth in height of the cartilage layers of the distal epiphyses of fractured radii was primarily stimulated when estrone-treated chicks were also exposed to the 2-G state. Appositional growth of all cartilage layers of the proximal and distal epiphyses of normo-gravity birds was increased by 0.2 mg estrone. In addition, growth in the width of all cartilage layers of the distal epiphyses of 2-G animals was increased with the administration of 0.4 mg estrone.
mesh_terms: D000818:Animals; D002356:Cartilage / Q000187:drug effects / Q000254:growth & development* / Q000473:pathology; D002645:Chickens; D004838:Epiphyses / Q000187:drug effects / Q000254:growth & development* / Q000473:pathology; D004970:Estrone / Q000494:pharmacology*; D005260:Female; D006112:Gravitation; D011885:Radius Fractures / Q000473:pathology / Q000503:physiopathology
chemical_list: D004970:Estrone