Fig. 5: VE-cadherin at adherens junctions between cells of the arachnoid and pia mater.

A, B Representative images of 20-µm coronal frozen sections of the brain of a healthy VE-cadherin-GFP reporter mouse perfused with tomato lectin-DyLight 594 (red), acquired with a confocal laser scanning microscope equipped with the Airyscan detector. Brains were cut ~1 mm caudal to the bregma. Immunostaining for α-catenin (A) and β-catenin (B) is magenta. Colocalization of the VE-cadherin-GFP signal (green) with α-catenin or β-catenin immunoreactivity (magenta) in the leptomeninges is white. Optical section = 0.16 µm. MIP, maximal intensity projection. Scale bars = 10 µm (left 2 columns); 2 µm (right 3 columns of zoomed-in images). Images are representative of three independent experiments. C Representative image of a 50-µm transverse frozen section of the decalcified head of a healthy VE-cadherin-GFP (green) reporter mouse perfused with tomato lectin-DyLight 594 (red), acquired with a confocal laser scanning microscope. Continuous linear patterns of VE-cadherin-GFP⁺ junctions in vascular endothelial cells (yellow arrowheads) differ from the more punctate pattern of VE-cadherin-GFP⁺ junctions between leptomeningeal cells (white arrowheads). Longitudinally oriented arterial endothelial cells, aligned with the direction of blood flow, are readily distinguished from polygonal endothelial cells in a venule. The XY MIP image was compiled from 20 optical sections, each 0.17 µm thick. Scale bar = 10 µm. Images are representative of three independent experiments. D TEM image of the cellular layers of the arachnoid with intercellular junctions marked by colored arrowheads. Tight junctions (zonula occludens), adherens junctions (intermediate junctions or zonula adherens), and gap junctions were identified by criteria described in the Methods. Blue arrowheads mark the basement membrane of a region of inner arachnoid cells facing a wide intercellular space. Subarachnoid and subdural spaces are labeled accordingly. Scale bar = 2 µm. Image is representative of TEM images of arachnoid from three mice.