The metabolism of some thyroid hormones by limb-bone rudiments cultivated in vitro

A novel approach for studying the temporal modulation of embryonic skeletal development using organotypic bone cultures and microcomputed tomography

Understanding the structural development of embryonic bone in a three dimensional framework is fundamental to developing new strategies for the recapitulation of bone tissue in latter life. We present an innovative combined approach of an organotypic embryonic femur culture model, microcomputed tomography (μCT) and immunohistochemistry to examine the development and modulation of the three dimensional structures of the developing embryonic femur. Isolated embryonic chick femurs were organotypic (air/liquid interface) cultured for 10 days in either basal, chondrogenic, or osteogenic supplemented culture conditions. The growth development and modulating effects of basal, chondrogenic, or osteogenic culture media of the embryonic chick femurs was investigated using μCT, immunohistochemistry, and histology. The growth and development of noncultured embryonic chick femur stages E10, E11, E12, E13, E15, and E17 were very closely correlated with increased morphometric indices of bone formation as determined by μCT. After 10 days in the organotpyic culture set up, the early aged femurs (E10 and E11) demonstrated a dramatic response to the chondrogenic or osteogenic culture conditions compared to the basal cultured femurs as determined by a change in μCT morphometric indices and modified expression of chondrogenic and osteogenic markers. Although the later aged femurs (E12 and E13) increased in size and structure after 10 days organotpypic culture, the effects of the osteogenic and chondrogenic organotypic cultures on these femurs were not significantly altered compared to basal conditions. We have demonstrated that the embryonic chick femur organotpyic culture model combined with the μCT and immunohistochemical analysis can provide an integral methodology for investigating the modulation of bone development in an ex vivo culture setting. Hence, these interdisciplinary techniques of μCT and whole organ bone cultures will enable us to delineate some of the temporal, structural developmental paradigms and modulation of bone tissue formation to underpin innovative skeletal regenerative technology for clinical therapeutic strategies in musculoskeletal trauma and diseases.

Effect of testosterone on fracture healing in hypophysectomized rats

The effect of hypophysectomy and hypophysectomy + testosterone treatment on fracture healing was investigated on 60 Wistar rats (30 day old). The aim of the experiment was to elucidate whether in callus formation testosterone acts directly on the cells (peripheral effect), or its effect is mediated through the hypophysis (central effect). Changes induced by hypophysectomy take place in the course of callus formation due primarily to the impairment of the enzyme system of the cells. The effect of hypophysectomy can be attenuated with testosterone which, despite hypophysectomy, stimulates fracture healing. It may be concluded that testosterone exerts a direct peripheral effect on the callus cells, presumably on their enzyme system.