👉 Stroma, in medical terms, refers to the outer layer of cells and other components that surround a cell or tissue. This term is often used when describing the structure of blood vessels, which are a type of stroma. The term "stroma" comes from Greek, meaning "softness," as it can be soft and flexible, like a jelly, but also hard and rigid, resembling a sponge. In general, the stroma is composed of several different types of cells, including macro