CONTRAST-ENHANCING OPTICAL METHOD TO OBSERVE A BONGHAN DUCT FLOATING INSIDE A LYMPH VESSEL OF A RABBIT

Abstract

Novel threadlike structures, so-calledBonghan ducts (BHDs), were recentlyrediscovered inside large caliber lymphaticvessels using two different staining dyes inrabbits (Janus green B and Alcian blue) andfluorescent nanoparticles in rats. These threemethods have the drawback of injectingchemical agents into the lymphatic vessels,which might damage the BHD and hinderfurther investigation of its physiologicalfunction. New methods to observe BHDswithout using external chemical agents needto be developed. In the present work, weintroduce a contrast enhancing optical methodfor in vivo observation of BHDs floating insidelarge caliber lymph vessels. The method uses alow-pass filter above about 650 nm, with anarrangement to minimize the light reflectedfrom the surface of the lymph vessel. Wecaptured films showing movement of a BHDas the animal respired. Applying the previousAlcian blue injection technique, we obtainedBHD samples from the lymph vessel andobserved the distribution of rod-shape nuclei(the essential feature of a BHD). BHDs cannow be observed inside lymph vessels by usingcontrast-enhancing instrumentation withoutvisualizing chemical agents.