The purpose of this study was to examine the morphological changes in an in vitro system in which the two elements of bone modelling, formation and resorption, could be studied simultaneously. Pregnant @entity19 were killed on days 15, 16 and 17 of gestation, the fetuses were removed and the radii and ulnae dissected free of soft tissue. The bones were cultured for 6 days in media (BGJ) supplemented with 20% fetal calf serum and 150 micrograms/ml @entity620 . Growth and mineralization were estimated by measuring the total length of the bone, and diaphysis, and by light and @entity1579 ( @entity1579 ). The results of this study indicate that there is a continuous measurable increase in the total length of fetal @entity19 long bones over the 6 days of culture. These bones show a continuous growth of periosteal bone, with mesenchymal tissue penetrating into the diaphyseal shaft, and development of bone marrow like tissue. @entity1579 examination showed differentiation of mesenchymal cells to osteoblasts, formation of new bone matrix and bone mineralization similar to that found in developmentally matched controls. In the cartilagenous epiphyses, however, many @entity692 crystals were not associated with matrix vesicles. In addition, some of the chondrocytes of the @entity1184 zone appeared to be dedifferentiating into mesenchymal cells with osteoblast-like features. In spite of the lack of osteoclasts in the 15- and 16-day explants, osteoclasts appeared in the diaphysis after 2 and 4 days in culture. Our results suggest that this system can serve as a good model for the study of bone formation and resorption as they occur, simultaneously, during bone modelling.(ABSTRACT TRUNCATED AT 250 WORDS)

An in vitro assay of bone development using fetal long bones of XXXX : morphological studies.

@entity19 :: ('10090', 'Species') :: ['mice', 'mouse'] @entity1184 :: ('MESH:D006984', 'Disease') :: ['hypertrophic'] @entity620 :: ('MESH:D001205', 'Chemical') :: ['vitamin C'] @entity1579 :: ('MESH:D017096', 'Disease') :: ['transmission electron microscopy', 'TEM'] @entity692 :: ('MESH:D017886', 'Chemical') :: ['hydroxyapatite']
@entity19 :: (10090,Species) :: ['mice']
