e cavity in caudal vessels. (**B**) Quantification of ISV length in 00 hpf control embryos and embryos exposed to the indicated doses of PEG-*b*-PCL nano-micelles. (**C**) In situ hybridization analysis of *flk0* expression in 00 hpf control embryos and embryos exposed to the indicated doses of PEG-*b*-PCL nano-micelles. 