The Effect of Trypan Blue on the Growth Rate of the Chick Embryo During Development
Watkins, Edgar H.
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The problem. This is a study to determine if the growth rate of the developing chick embryo is changed by the teratogenic agent, trypan blue. Procedure. The eggs were divided into three groups, unopened controls, saline-injected (0.1 ml, 0.85 NaCl) standards and trypan-blue-injected (0.1 ml, 0.1% solution) experimentals. Injections were made into the yolk sac through the blunt end of the egg during the 48th hour of incubation. Six independent variables, wet weight, dry weight, ash weight, organic content, weight of water and per cent of water of wet weight, were used to determine the effect of the dye on the embryos growth rate. The measurements were taken daily over a 17 day incubation period (4th to 20th day). Findings. There were no consistently significant differences between the groups but a trend of lower weights for the experimental group developed over the last seven days. Constant death rate and early malformations observed point to the early effect of trypan blue on the chick embryo. On the 14th day significant differences were recorded for five of the six variables between the controls and experimentals. Conclusions. If there is an effect on total growth of the embryo in later development it is too small to be significant with the sample size used in this study. A long effect on total growth does not appear to be a mechanism for the teratogenicity of trypan blue. Recommendations. The development around the 14th day might be worth examining further to see if there is a triggering in the metabolic processes whioh cause the weights to be consistently lower the last seven days of development.