Abstract
Bone obtained from the interior of the shaft of the tibia in 6 young post-embryonic chicks was explanted in a hanging-drop culture of plasma and embryonic extract. The explant quickly became surrounded by a halo of cells and on the 6th day of ex-plantation, the original bone was dissected out and discarded. In 29 of 190 explants cartilage of hypertrophic type was found in the new growth. This remains relatively undifferentiated and in many cases becomes directly transformed into osteoid tissue and bone. Chondrogenesis was sometimes present as early as 9 days after explantation.