fibroblast

Examples of fibroblast in the following topics:

• Connective Tissues: Loose, Fibrous, and Cartilage

  • The principal cell of connective tissues is the fibroblast, an immature connective tissue cell that has not yet differentiated.
  • Fibroblasts are motile, able to carry out mitosis, and can synthesize whichever connective tissue is needed.
  • Loose connective tissue has some fibroblasts, although macrophages are present as well.
  • The fibers and other components of the connective tissue matrix are secreted by fibroblasts.

• Structural Elements of Connective Tissue

  • The fibroblast is the most common cell which creates collagen.
  • Elastic fibers (or yellow fibers) are bundles of proteins (elastin) found in extracellular matrix of connective tissue and produced by fibroblasts and smooth muscle cells in arteries.

• Bone Repair

  • The bone marrow (when present), endosteum, small blood vessels, and fibroblasts are other sources of precursor cells.
  • The fibroblasts within the granulation tissue develop into chondroblasts that also form hyaline cartilage.

• Bone Remodeling

  • These factors include insulin-like growth factors I and II, transforming growth factor beta, fibroblast growth factor, platelet-derived growth factor, and bone morphogenetic proteins.
  • Fibroblast growth factor activates various cells of the bone marrow including osteoclasts and osteoblasts.

• Postnatal Bone Growth

  • In essence, osteoblasts are specialized fibroblasts that, in addition to fibroblastic products, express bone sialoprotein and osteocalcin.

• Bone Remodeling and Repair

  • Though fragments of the blood clot may remain, fibroblasts and osteoblasts enter the area and begin to reform bone.
  • Fibroblasts produce collagen fibers that connect the broken bone ends, while osteoblasts start to form spongy bone.

• Epidermal Wound Healing

  • Since the dermis is intact, local fibroblasts are able to contribute to the formation of a new basement membrane, upon which the epidermis sits.

• Steps of Tissue Repair

  • Granulation: Fibroblasts attracted to the wound site quickly lay down a temporary extra cellular matrix, comprised of collagen and fibronectin, upon which the epidermis can be reconstituted.
  • Contraction: Re-epithelization is thought to occur simultaneously with contraction, where myo-fibroblasts recruited around the wound site pull against each other to contract the size of the wound.
  • The epidermis proliferates and returns to its normal character; fibroblasts and immune cells which were recruited to the site are degraded; and the temporary extra cellular matrix that was laid down is remodelled into a stronger, more permanent structure.

• Basement Membranes and Diseases

  • The electron-dense lamina densa membrane is about 30–70 nanometers in thickness, and consists of an underlying network of reticular collagen (type IV) fibrils (fibroblast precursors) which average 30 nanometers in diameter and 0.1–2 micrometers in thickness.

• Muscle Development

  • In the early development of an embryo, these myoblasts will proliferate if enough fibroblast growth factor (FGF) is present.