B. 
C. 
B.
C.
Figure 6. Posterior regions of zebrafish embryos approximately 70 hours after treatment with retinoic acid. The amount of pigment in embryos varies between the control (A) and the embryos treated with the 10-11 M (B) and 10-10 M (C) solutions, but this variation is not correlated to the concentration of retinoic acid with which the embryos were treated.