Figure 2
From: Participation of Intussusceptive Angiogenesis in the Morphogenesis of Lobular Capillary Hemangioma

(A–D) Mitoses are observed in a stalk cell of a loop (A, arrow), and in endothelial cells (B and C, arrows) and in a pericyte (D, arrow) of mother vessels. In the insert of C, note cells expressing ki67 (arrows) in the wall of a mother vessel. In C, note a sprout emerging from a mother vessel (arrowhead). (E–G) Incorporation of pericytes or their processes (arrows) around ECs and formation of new vessel lumens (lu). (H–K) Vessel loops surrounding interstitial tissue structures (ITSs) are observed in double-staining (H) and in serial semi-thin sections (a dashed line delimits the loop, (I–K). In H, the loop encircling an ITS shows CD34+ ECs (brown) and αSMA+ pericytes (red). Perforated and unperforated interendothelial contacts from the opposite walls of the loops are seen alternating with zones in which the loop lumen (asterisk) is open (H–K). Note the presence of red blood cells in the open spaces of the loop (I–K). (A,B,F,G) Ultrathin sections. Uranyl acetate & Lead citrate. (C–E,I–K) Semithin sections stained with Toluidine Blue (I–K) serial sections). (H) Double-stained section with anti-CD34 (brown) and anti-αSMA (red). Bar: (A,B,F,G) 4 µm; (C,D) 10 µm; (H) 20 µm; (E–K) 25 µm.