Granulation tissue
1994785
213008681
2008-05-17T09:20:46Z
Snellios
111569
Added {{[[Template:refimprove|refimprove]]}} tag to article. using [[WP:FRIENDLY|Friendly]]
{{refimprove|date=May 2008}}
'''Granulation tissue''' is the [[perfusion|perfused]], fibrous connective tissue that replaces a [[fibrin]] clot in [[wound healing|healing wounds]]. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size it heals.
==Appearance==
[[Image:DSC07406.JPG|thumb|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:
* [[extracellular matrix]],
* [[immune system]], or
* [[angiogenesis|vascularisation]].
An excess of granulation tissue is informally referred to as "proud flesh."<ref>[http://compepid.tuskegee.edu/syllabi/pathobiology/pathology/genpath/chapter9.html Healing and Repair] Chapter 9 from an "Introduction to Pathology" on a [[Tuskegee University]] website</ref>
===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 insult. 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 defence.
===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. [[Fibroblast]]s, 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 vessel]]s. These branch out in a systematic way, forming [[anastomosis|anastomoses]] with other vessels.
==References==
<References/>
[[Category:Anatomical pathology]]
[[pl:Ziarnina]]