Fig. 4. Endothelial cells without FLVCR1a show paraptotic cell death morphological features.

a-i Electron microscopy analysis performed on transverse section from E11.5 embryonic forelimbs. Two capillaries from a control a, b and an eKO d, e embryo are shown. Flvcr1a null ECs display extensive cytoplasmic vacuolation d, e and an altered swollen morphology of ER and mitochondria f compared with controls c. In g, a small limb capillary made of two Flvcr1a null ECs is shown. The presence of huge intracellular vacuoles and heavily damaged mitochondria without cristae (black arrowheads) is clearly visible in the enlargements h, i. eKO Flvcr1a endothelial knockout; BC blood cell; EC endothelial cell; IEJ inter endothelial junction; V vacuole; M mitochondrion; N nucleus; ER endoplasmic reticulum