Visualization of Bonghan Microcells by Electron and Atomic Force Microscopy

(A) Bonghan ducts on the surface of rat small intestine. Connections of ducts and corpuscles indicated by arrows; scale bar, 200 μm. (B) Macro and microcells naturally flowing out from Acridine orange stained cut; various sizes of microcells (arrows) stained among leukocytes. (C, D) Bonghan microcells (BH-MCs), 1-2 μm in size, separated by differential centrifugation, DNA-containing BH-MCs selected; two microcells, one on right stained with Acridine orange. Scale bars, 10 μm for Figure B, D.

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of Bonghan microcells (BH-MCs) on polycarbonate membrane filter. (A) SEM image showing round BH-MCs, ∼1 μm diameter; scale bar, 5 μm. (B) High magnification showing bumpy surface structure; scale bar, 200 nm. (C) DNA-containing BH-MC selected by staining; TEM of ultrathin section; largest part assumed to be micronucleus “N” based on Acridine orange staining; several 250 nm sized granules and many smaller granules inside membrane; all granules surrounded by lipid membrane and with electron dense contents; scale bar, 500 nm. (D) Magnification of (C) rectangle showing the border of the micronucleus “N”; the membrane is not a double bilayer structure as in a nuclear membrane; scale bar, 100 nm.

Unique threadlike structure of lyophilized Bonghan microcells observed in (A) a scanning electron microscopy image, (B) atomic force microscopy (AFM) height image, and (C) AFM phase image. First step of budding, protrusion of threadlike structure from Bonghan microcells, arrows; bi-thread shape visible in AFM phase image; scale bars, 2, 1, and 1 μm, respectively.