The effect of
p-nitrophenyl beta-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 alpha-D-xyloside, p-nitrophenyl beta-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 beta-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.