When I see diagrams of cellular structures such as the layers of the skin, these diagrams show the cells as being closely packed together. For example here is a typical such diagram:
So, it shows the capillaries of the vascular system going only to the bottom of the many layers of tightly packed cells. So, I assume that all the cells need oxygen, so they all need to be in contact with the blood cells that bear oxygen, so how does this happen? Obviously each individual cell can't have its own personal capillary. If blood were to be released just loosely around the cells that would not work either because the blood would have no way to get back. All the blood has to be in vessels of some kind so it can circulate. But these vessels are not shown as reaching the upper skin cells in any way, so how are those cells getting oxygen?