Prepared from mouse plasma. Country of Origin: Mouse plasma was obtained from healthy animals of US origin and under the care of a registered veterinarian. Product Citation: DSouza AV, Marra K, Gunn JR, Samkoe KS, Pogue BW. Optical tracer size differences allow quantitation of active pumping rate versus Stokes–Einstein diffusion in lymphatic transport. J Biomed Opt. 2016 Oct 1;21(10):100501. doi: 10.1117/1.JBO.21.10.100501. Tichauer KM, et al. Microscopic lymph node tumor burden quantified by macroscopic dual-tracer molecular imaging. Nat Med. 2014 Nov;20(11):1348-53. doi: 10.1038/nm.3732. Epub 2014 Oct 26. Tichauer KM,et al. Lymph node microscopic tumor burden quantified in vivo with dual tracer receptor-targeted imaging. Biomedical Optics 2014 OSA Technical Digest (online) (Optical Society of America, 2014), paper BS3A.44 https://doi.org/10.1364/BIOMED.2014.BS3A.44.