A study of the effects of trypan blue injected into amphibian zygotes.

Trypan blue was injected (0.001-0.002 mg/egg) into zygotes ofRana. The trypan blue-injected series showed much greater mortality than the controls. A probable suppression of gastrulation was seen. 29.7% of the dye-injected and 50.3% of the control embryos developed beyond stage 14. Abnormalities seemed to appear only after neurulation began. Microcephaly, trunk and tail abnormalities occurred though in a small number. Sections of a few embryos revealed disorganized brain and degeneration of the neural tissue. There were no cases of mesodermalization of the notochord.The results are discussed from the view point that trypan blue alters the physical state of proteins in the cytoplasm of the egg.