Stromal cells

In cell biology, stromal cells are connective tissue cells of an organ found in the loose connective tissue. These are most often associated with the uterine mucosa (endometrium), prostate, bone marrow precursor cells, and the ovary as well as the hematopoietic system and elsewhere. These are the cells that make up the support structure of biological tissues and support the parenchymal cells. Fibroblasts, immune cells, pericytes, endothelial cells, and inflammatory cells are the most common types of stromal cells. The interaction between stromal cells and tumor cells is known to play a major role in cancer growth and progression. Stromal cells near the bottom of the epidermis (the very top layer of the skin) release growth factors that promote cell division. This keeps the epidermis regenerating from the bottom while the top layer of cells on the epidermis are constantly being "sloughed" off of the body. Certain types of skin cancers (basal cell carcinomas) cannot spread throughout the body because the cancer cells require nearby stromal cells to continue their division. The loss of these stromal growth factors when the cancer moves throughout the body prevents the cancer from invading other organs.