Fibroblast cells. Confocal laser scanning micrograph of fibroblast cells. The cell nuclei, which contain the cells' genetic information, are yellow. Actin filaments, which make up part of the cytoskeleton, are blue. The cytoskeleton maintains the cells' shape, allows some cellular mobility and is involved in intracellular transport. Mitochondria, which produce energy for the cell, are green. Fibroblasts are cells that give rise to connective tissue such as collagen, the main structural protein in the body. They are important in wound healing.