Figure 1. Characteristic morphology and perivascular location of a mast cell (arrow), as seen in a one-micrometer-thick resin section stained with toluidine blue. The mast cell is close to the abluminal surface of the endothelium of this post-capillary venule. The basal epithelial layer (E) is seen in the upper right. Original magnification X1000. Scale bar indicates 5 µm.