Effects of growth hormone and thyroxine on the relation between tibial length and the histological appearance of the proximal tibial epiphysis in Snell dwarf mice.
The length of the tibia was studied in normal Snell mice (+/?) and in dwarfs (dw/dw) before and after treatment with human growth hormone (hGH) and thyroxine (T4) in relation with the histometrical development of the tibial proximal epiphysis. The aim of the study was to obtain more insight in the specific role of these hormones in the process of bone growth in animals lacking several pituitary hormones, due to a autosomal recessive gene mutation called dw. In normal mice increase in length of the tibia (PTL) is positively correlated with body length. PTL is also positively correlated with the increase in width of the metaphysis. In contrast, the height of the various zones in the growth plate show a negative correlation with PTL. This is linked to a proceeding ossification, as is shown by the positive correlation of PTL with the size of the secondary ossification centre and number of capillaries. In dwarfs the relation between PTL, the heights of the various zones, the metaphyseal width and the number of capillaries strongly deviates from the normal situation. The size of the secondary ossification centre is only slightly below the normal range. Administration of hGH has a stimulating effect on the proliferating and degenerating zones of the growth plate. T4 exerts its main influence both on the size of the secondary ossification centre and on the rest-zone, which both shift into the normal range. Vascularization is normalized both by hGH and T4.
D000818:Animals; D002196:Capillaries / Q000254:growth & development; D004838:Epiphyses / Q000033:anatomy & histology / Q000254:growth & development*; D013006:Growth Hormone / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D010012:Osteogenesis; D013974:Thyroxine / Q000494:pharmacology / Q000502:physiology*; D013977:Tibia / Q000033:anatomy & histology / Q000098:blood supply / Q000254:growth & development*
D013006:Growth Hormone; D013974:Thyroxine