Novel threadlike structures (Bonghan ducts) inside lymphatic vessels of rabbits visualized with a Janus Green B staining method

TLDR

The existence of this novel threadlike structure was not noticed previously because it is extremely difficult to detect it by microscopic inspection of lymphatic vessels. The tissue was studied by confocal laser scanning microscopy, light microscopy, and cryoscanning electron microscopy. Using Janus Green B, the authors visualized a previously undetected threadlike structure inside rabbit lymphatic vessels, revealing rod‑shaped nuclei aligned in a striped pattern, distinct passage through valves, presence within collapsed vessels, and globular intraluminal bodies suggestive of fluid flow, with staining indicating high mitochondrial density or nerve‑like properties that may hint at physiological roles. © 2005 Wiley‑Liss, Inc., Anat Rec (Part B: New Anat) 286B:1–7, 2005.

Abstract

Abstract A staining method has been developed for in situ and in vivo observation of a threadlike tissue afloat inside the lymphatic vessels of rabbits without adherence to the vessel wall. The existence of this novel structure was not noticed previously because it is extremely difficult to detect it by microscopic inspection of lymphatic vessels. We have found a method that utilizes Janus Green B (JGB), which stained heavily the novel structure. The tissue was studied by confocal laser scanning microscopy (CLSM), light microscopy, and cryoscanning electron microscopy (cryo‐SEM). The CLSM image obtained by acridine orange staining of the novel tissue revealed its characteristic nuclei distribution: rod‐shaped nuclei of 10–20 μm length aligned in a broken‐line/striped fashion. Hematoxylin and eosin staining revealed the threadlike structure passing through a lymphatic valve as histologically distinct from lymphatic vessels and valves. The cryo‐SEM image showed the threadlike structure inside a collapsed lymphatic vessel. There were spherical globular structures observable inside sinuses in a rapidly frozen sample, which suggests liquid flowing through the longitudinal ductules in the threadlike structure. The specific staining of the JGB suggests that these threadlike structures inside lymphatic vessels have a high density of mitochondria in their cells and/or nerve‐like properties, either of which may provide important clues to their physiological function. Anat Rec (Part B: New Anat) 286B:1–7, 2005. © 2005 Wiley‐Liss, Inc.