This study aims to investigate the ultrastructural morphological changes that occur in the interactions between pericytes and endothelial cells in mice lacking the Notch3 receptor and in diabetic retinopathy.<h4>Methods</h4>Serial section transmission electron microscopy (ssTEM) was used to image mouse retinal ganglion cell layer capillaries in wild type (WT; 19 vessels), Notch3 knockout (KO; 16 vessels), conditional Notch3 KO (23 vessels), and diabetic mice (18 vessels). The gene discussed is NOTCH3; the disease is diabetic retinopathy.