The effect of p-nitrophenyl β-D-xyloside, an inhibitor of proteoglycan biosynthesis, on the growth of chick embryos was studied by injection of the single dose of 1·0 mg/egg into fertile eggs on day 3. Embryos examined on day 10 had systemic edema, and were increased not only in wet weight (142% of the non-treated embryos) but also in dry weight (125%). No skeletal malformations were observed in the treated embryos. The glycosaminoglycan content in the treated embryos began to increase 6 h after treatment and reached the maximum level (174% of the non-treated) after 3 days, while the DNA and protein content began to increase 12 h after treatment and reached the maximum level (about 140%) within 3 days. P-Nitrophenyl α-D-xyloside, P-nitrophenyl β-D-galactoside, and a mixture of p-nitrophenol and D-xylose produced neither the abnormal overgrowth nor the edematous change of chick embryos.
When fertile eggs were treated with 1·0 mg/egg of p-nitrophenyl β-D-xyloside on day 6, the increase in wet and dry weights was also observed in all surviving embryos. On the contrary, treatment on day 9 resulted in the slight reduction of embryonic growth in addition to the systemic edema. Both embryos treated on day 3 and on day 6 contained glycosaminoglycans rich in chondroitin 6-sulfate, whereas the embryos treated on day 9 contained glycosaminoglycans rich in undersulfated chondroitin sulfates. These findings seem to support the view that glycosaminoglycans play an important role in the regulation of embryonic growth.
Histochemical and radiographic investigations of Malathion-induced malformations in embryonic chick limbs
