Comparison of the Characteristic Features of Bonghan Ducts, Blood and Lymphatic Capillaries

Stereomicroscopic images of Bonghan ducts and corpuscle on the surface of rabbit internal organs. (A) Bonghan duct (arrow) on large intestine surface (LI); intact duct, a semitransparent, freely movable tissue structure. (B) Bonghan duct (arrow) after methylene blue staining. (C) Bonghan corpuscle (arrowhead) on small intestine (SI) linked with Bonghan ducts (arrows); corpuscle and ducts contrasted using methylene blue.

H&E stained cross-sections of a profound Bonghan corpuscle. (A) Light microscopic image of histological structure of corpuscle; low magnification; dashed line areas indicate gathering of different cell types, similar to follicular formation; scale bar, 50 μm. (B) Details of ductules (arrows) in corpuscle; scale bar, 10 μm. (C) Ductules (arrows) between follicle-like clusters of immune cells; scale bar, 10 μm. (D) Small basophilic bodies (G) in the ductule (arrow); scale bar, 10 μm. (E) Enlargement of area in rectangle of Figure 2D; scale bar, 5 μm. (F) Photomicrograph of boundaries (arrowhead) of corpuscle not surrounded by external connective tissue membrane; “E” = endothelial cell; M = monocyte/ macrophage; Gr = granulocyte; L = lymphocyte; scale bar, 10 μm.

Histological structure of the Bonghan duct. (A) Photomicrograph of merged phase-contrast and fluorescent images of a duct; duct formed by bundle of several ductules (arrows) with characteristic rod-shaped nuclei stained with DAPI (blue); immune cells (arrowheads) on duct surface; scale bar, 50 μm. (B) Photomicrograph of several ductules in cross section through duct; small insert, general histological view of duct; scale bar, 10 μm.

Ultrastructural organization of the ductule. (A) Electron micrograph of ductule (asterisk) cross-section; scale bar, 2 μm. (B) Magnified image of rectangular area in Figure 4A showing wall (W) of ductule as single layer of endothelial cells surrounded by fibrin-like fibers; scale bar, 1 μm. (C, D) High magnification EM showing ultrastructural characteristics of ductule endothelial cells; L = lumen; M = mitochondria; RER = rough endoplasmic reticulum; P = cytoplasmic protrusion; ICP = interdigitated cytoplasmic processes; Pv = pinocytotic vesicles; V = vacuole; and F = fibrin-like fibers; scale bar, 0.5 μm.

Microscopic view of the ductule. (A) Low magnification EM of duct cross section; scale bar, 2 μm. (B-D) Magnified images of rectangular areas in Figure 5A showing ultrastructural features of ductule endothelial cell; L = lumen; RER = rough endoplasmic reticulum; OCP = overlapping cytoplasmic processes; P = cytoplasmic protrusion; V = vacuole; F = fibrin-like fibers; scale bar, 0.5 μm.

Electron micrographs showing ultrastructural characteristics of lymphatic (A) and blood (D) capillaries of rabbit. Scale bar, 2 and 1 μm, respectively. (B, C) magnified images of rectangular areas in Figure 6A; scale bar, 0.5 μm. (E) Magnified image of rectangular areas in Figure 6D showing blood capillary ultrastructural features; L = lumen; W = wall of lymphatic capillary; C = collagen fibers; Pv = pinocytotic vesicles; Sv = surface vesicles; BL = basal lamina; N = nucleus; M = mitochondria; RER = rough endoplasmic reticulum; J = junction of the endothelial cell; Er = erythrocyte; scale bar, 0.5 μm.

Structural properties of Bonghan ductule and of blood and lymphatic capillary. E = endothelium; L = lumen; AC = accessory cell; CBL = complete basal lamina; IBL = incomplete basal lamina.