Abstract
Evaluation of the effect of S35, afrinitive to the bone and cartilage, on the development of bone in chick embryo were studied.
Method: One tenth cc aqueous solution of S35 containing 6 different concentrations ranging from 300, μc to 12.5 μc was injected into the yolk of the fertilized eggs of white Leghorn before the incubation, at the second, fourth and sixth day of the incubation, including the third day of incubation when the limb bud developed. All incubated eggs were opened when they were dead or at the 19 th incubation day, and they were examined.
Results:
1) Acute death occurred in many of the young embryos, and late death occurred most frequently at the fourth incubation day, decreasing their frequency at the second, sixth incubation day and pre-incubation in order.
2) S35 showed strong activity to develop malformation in a wide sense.
3) More prominent growth-inhibiting activity, such as a decrease in body weight and shortening of the femoral long axis, and the histological findings of the bone was seen as the dosis of irradiation increased. They were the most prominent in the 4 day incubation group of the eggs of the fourth incubation day, decreasing their frequency in the eggs of the second, sixth incubation day and pre-incubation in order.
4) Degeneration of the chondrocytes was the most prominent histological change, and, in addition, degeneration of the obsteocytes and a decrease in the number of the osteoblasts are recognized constantly. Cartilageremnant and fibrosis of the island-like obteotrabeculae were recognized in the bone tissues characteristically.
