SEM of human fibroblast cells growing on microcarrier beads. A fibroblast is a type of cell that synthesizes the extracellular matrix and collagen, the structural framework (stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells of connective tissue in animals. Microcarrier beads are used for the large-scale production of cells and cell by-products such as viruses, vaccines, and drugs (such as the interferons). The technique is preferred over petri dishes for growing "anchorage dependent" cells. From a production aspect, the available surface area on a small volume of beads is greater than a table covered in petri dishes. Magnification 550x.