Fig. 6

Z-stack images obtained from 100 μm thick sections double-labeled for the endothelial marker UEA-l (brown) and COLL4 (blue) showing endothelial damage and various stages of string vessels. a Gradual loss of the endothelium in an early string vessel (S1 type) that connects two other vessels. b Focal endothelial damage with a large COLL4-positive bag (star) in the vicinity of areas with vascular bagging (thin black arrows). c Early string vessel of the S2 type with an empty collagenous tube that connects two vessels but completely lacks endothelial lining. d String vessel with a tube section (S2 type) and with a thin collapsed collagenous section classified as S3 type. e Fully collapsed string vessel (S3 type) between two vessels. f Segmented string vessel with extremely thin or broken sections (S4 type), which was called here a ghost string vessel or briefly string ghost. Images obtained from Case 1 (myocardial infarction, NoSVD) (a, c and d), Case 6 (non-hodgkin lymphoma, “pure” SVD) (b and e), and Case 9 (chronic hypertension, “pure” SVD) (f). For viewing tubular and ghost string vessels, also see Additional file 2: Video S1 of Vessels. Thin black arrows: vascular bags; thick black arrows: origin or segment of string vessel. Scale bars: 50 μm