Changes

==Introduction==

==Introduction==

<p>''Also called aggregated nodules''</p>

<p>''Also called aggregated nodules''</p>

<p>Peyer’s patches are lymphoid tissues found in the wall of the [[Small Intestine - Anatomy & Physiology|small intestine]]. They are part of the [[Regional Lymphoid Tissue - Anatomy & Physiology|mucosal-associated lymphoid tissues (MALT)]] and more specifically the gut-associated lymphoid tissue (GALT). Although nodules of lymphatic tissue are found throughout the intestines in the [[Small Intestine - Anatomy & Physiology|small intestine]] larger collections of nodules exist and these are referred to as Peyer’s patches. In many species they act as a [[:Category:Primary Lymphoid Tissue|primary lymphoid tissue]] (cattle, sheep , pigs, horses, dogs and rabbits).</p>

<p>Peyer’s patches are lymphoid tissues found in the wall of the [[Small Intestine Overview - Anatomy & Physiology|small intestine]]. They are part of the [[Regional Lymphoid Tissue - Anatomy & Physiology|mucosal-associated lymphoid tissues (MALT)]] and more specifically the gut-associated lymphoid tissue (GALT). Although nodules of lymphatic tissue are found throughout the intestines in the [[Small Intestine Overview - Anatomy & Physiology|small intestine]] larger collections of nodules exist and these are referred to as Peyer’s patches. In many species they act as a [[:Category:Primary Lymphoid Tissue|primary lymphoid tissue]] (cattle, sheep , pigs, horses, dogs and rabbits).</p>

==Development ==

==Development ==

<p>In cattle, sheep , pigs, horses and dogs over eighty percent of the patches are found in the [[Ileum - Anatomy & Physiology|ileum]] where they form a continuous structure which is most developed before birth and regresses to the point that in the adult they cannot be detected. The rest of the patches are found in the [[jejunum - Anatomy & Physiology|jejunum]] and are isolated from each other, however these patches last throughout adult life.</p><p> In rabbits and rodents the patches are randomly located along both the [[Ileum - Anatomy & Physiology|ileum]] and [[jejunum - Anatomy & Physiology|jejunum]] and persist throughout life.</p>

<p>In cattle, sheep , pigs, horses and dogs over eighty percent of the patches are found in the [[Ileum - Anatomy & Physiology|ileum]] where they form a continuous structure which is most developed before birth and regresses to the point that in the adult they cannot be detected. The rest of the patches are found in the [[jejunum - Anatomy & Physiology|jejunum]] and are isolated from each other, however these patches last throughout adult life.</p><p> In rabbits and rodents the patches are randomly located along both the [[Ileum - Anatomy & Physiology|ileum]] and [[jejunum - Anatomy & Physiology|jejunum]] and persist throughout life.</p>

==Structure==

==Structure==

Peyer’s patches are located in the lamina propria and submucosa of [[Small Intestine - Anatomy & Physiology|small intestine]] and may be distinguishable by the lack of villi covering them. The patches are regions of concentrated [[Lymphocytes#B cells|B lymphocyte]] follicles covered in a ‘dome’ of a specialised follicle associated epithelium (FAE) which consists of follicle associated enterocytes and M (microfold or multifold) cells.  

Peyer’s patches are located in the lamina propria and submucosa of [[Small Intestine Overview - Anatomy & Physiology|small intestine]] and may be distinguishable by the lack of villi covering them. The patches are regions of concentrated [[Lymphocytes#B cells|B lymphocyte]] follicles covered in a ‘dome’ of a specialised follicle associated epithelium (FAE) which consists of follicle associated enterocytes and M (microfold or multifold) cells.  

===M cells===

===M cells===

M cells transport antigens from the intestinal lumen to the lymphocytes. Their luminal surface is folded and takes up antigens from the intestine via endocytosis and transports them to the extracellular space on their basal surface where the antigen is processed by antigen presenting cells.

M cells transport antigens from the intestinal lumen to the lymphocytes. Their luminal surface is folded and takes up antigens from the intestine via endocytosis and transports them to the extracellular space on their basal surface where the antigen is processed by antigen presenting cells.