Granulation tissue


Granulation tissue

Granulation tissue is the perfused, fibrous connective tissue that replaces a fibrin clot in healing wounds. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size it heals. In addition, it is also found in ulcers like oesophageal ulcer.

Contents

Appearance

Example of granulation tissue from a cut on a finger with "proud flesh".

During the proliferative phase of wound healing, granulation tissue is:

  • light red or dark pink in color, being perfused (permeated) with new capillary loops or "buds";
  • soft to the touch;
  • moist; and
  • bumpy (granular) in appearance.

Structure

Granulation tissue is composed of tissue matrix supporting a variety of cell types, most of which can be associated with one of the following functions:

An excess of granulation tissue (caro luxurians) is informally referred to as "proud flesh."[1]

Extracellular matrix

The extracellular matrix of granulation tissue is created and modified by fibroblasts. Initially, it consists of a network of Type III collagen, a weaker form of the structural protein that can be produced rapidly. This is later replaced by the stronger, long-stranded Type I collagen, as evidenced in scar tissue.

Immunity

The main immune cells active in the tissue are macrophages and neutrophils, although other leukocytes are also present. These work to phagocytize old or damaged tissue, and protect the healing tissue from pathogenic infection. This is necessary both to aid the healing process and to protect against invading pathogens, as the wound often does not have an effective skin barrier to act as a first line of defense.

Vascularization

It is necessary for a network of blood vessels to be established as soon as possible to provide the growing tissue with nutrients, to take away cellular wastes, and transport new leukocytes to the area. Fibroblasts, the main cells that deposit granulation tissue, depend on oxygen to proliferate and lay down the new extracellular matrix.

In vascularisation, also called angiogenesis, endothelial cells quickly grow into the tissue from older, intact blood vessels. These branch out in a systematic way, forming anastomoses with other vessels.

Approximate times of the different phases of wound healing,[2] with substantial variation depending on wound size and healing conditions. Granulation tissue formation is seen in green box at days to weeks.

References

  1. ^ Healing and Repair Chapter 9 from an "Introduction to Pathology" on a Tuskegee University website
  2. ^ Reference list is found on image main page.

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • granulation tissue — n tissue made up of granulations that temporarily replaces lost tissue in a wound * * * the newly formed vascular tissue normally produced in the healing of wounds of soft tissue and ultimately forming the cicatrix; it consists of small,… …   Medical dictionary

  • granulation tissue — noun new connective tissue and tiny blood vessels that form on the surfaces of a wound during the healing process • Syn: ↑granulation • Derivationally related forms: ↑granulate (for: ↑granulation) • Hypernyms: ↑connect …   Useful english dictionary

  • granulation tissue — Highly vascularized tissue that replaces the initial fibrin clot in a wound. Vascularization is by ingrowth of capillary endothelium from the surrounding vasculature. The tissue is also rich in fibroblasts (that will eventually produce the… …   Dictionary of molecular biology

  • granulation tissue — noun Date: 1873 tissue made up of granulations that temporarily replaces lost tissue in a wound …   New Collegiate Dictionary

  • granulation tissue — Pathol. tissue formed in ulcers and in early wound healing and repair, composed largely of newly growing capillaries and so called from its irregular surface in open wounds; proud flesh. [1870 75] * * * …   Universalium

  • granulation tissue — /grænjəˈleɪʃən tɪʃu/ (say granyuh layshuhn tishooh) noun tissue composed largely of newly growing capillaries which forms on the surface of healing wounds and ulcers; proud flesh. {so called from its irregular surface} …   Australian English dictionary

  • tuberculous granulation tissue — the tissue that forms the characteristic tubercle in tuberculosis, composed of epithelioid cells in concentric masses, lymphocytes, and often Langhans giant cells …   Medical dictionary

  • Granulation — can refer to:*Granulation tissue, a product of healing in major wounds; *Granular synthesis, a sound synthesis method; *Solar granulation, a sign of turbulent convection on the Sun; or *a process used by goldsmiths or silversmiths to decorate… …   Wikipedia

  • Granulation — That part of the healing process in which rough, pink tissue containing new connective tissue and capillaries forms around the edges of a wound. Granulation of a wound is normal and desirable. * * * 1. Formation into grains or granules; the state …   Medical dictionary

  • granulation — /gran yeuh lay sheuhn/, n. 1. the act or process of granulating. 2. a granulated condition. 3. any of the grains of a granulated surface. 4. Pathol. a. the formation of granulation tissue, esp. in healing. b. See granulation tissue. 5. Astron.… …   Universalium