Figure 1. Cellular Architecture of the Aortic Valve.

Valve endothelial cells (VECs) line the outer surface of the valve and function as a barrier to limit inflammatory cell infiltration and lipid accumulation. The three middle layers of the valve are the fibrosa, spongiosa, and ventricularis. These layers contain valve interstitial cells (VICs) as the predominant cell type. The fibrosa is nearest the aortic side of the valve, contains Type I and Type III fibrillar collagen, and serves a load-bearing function. The spongiosa contains glycosaminoglycans (GAGs) that lubricate the fibrosa and ventricularis layers as they shear and deform during the cardiac cycle. The ventricularis contains elastin fibres to decrease radial strain. Source: Rajamannan, 2011.¹⁰