Serous membrane

Serous membrane

Infobox Anatomy
Latin = tunica serosa
GraySubject =
GrayPage =

Caption = Layers of the enteric nervous system. (Serosa at top, in red.)

Caption2 = Stomach. (Serosa is labeled at far right, and is colored yellow.)
Precursor = mesoderm
System =
MeshName = Serous+membrane
MeshNumber = A10.615.789
DorlandsPre = t_22
DorlandsSuf = 12832289

In anatomy, a serous membrane (or serosa) is a smooth membrane consisting of a thin layer of cells which excrete serous fluid. Serous membranes line and enclose several body cavities, known as serous cavities, where they secrete a lubricating fluid which reduces friction from muscle movement. Serosa is not to be confused with adventitia, a connective tissue layer which binds together structures rather than reducing friction between them.


Each serous membrane is composed of a secretory epithelial layer and a connective tissue layer underneath.
* The "epithelial layer", known as mesothelium, consists of a single layer of avascular flat nucleated cells (simple squamous epithelium) which produce the lubricating serous fluid. This fluid has a consistency similar to thin mucus. These cells are bound tightly to the underlying connective tissue.
* The "connective tissue layer" provides the blood vessels and nerves for the overlying secretory cells, and also serves as the binding layer which allows the whole serous membrane to adhere to organs and other structures.

For the heart, the surrounding serous membranes include:

Other parts of the body may also have specific names for these structures. For example, the serosa of the uterus is called the perimetrium.

The pericardial cavity (surrounding the heart), pleural cavity (surrounding the lungs) and peritoneal cavity (surrounding most organs of the abdomen) are the three serous cavities within the human body. It should be noted that while serous membranes have a lubricative role to play in all three cavities, in the pleural cavity it has a greater role to play in the function of breathing.

The serous cavities are formed from the intraembryonic coelom and are basically an empty space within the body surrounded by serous membrane. Early in embryonic life visceral organs develop adjacent to a cavity and invaginate into the bag-like coelom. Therefore each organ becomes surrounded by serous membrane - they "do not" lie within the serous cavity. The layer in contact with the organ is known as the visceral layer, while the parietal layer is in contact with the body wall.

Embryological origins

All serous membranes found in the human body formed ultimately from the mesoderm of the trilaminar embryo. The trilaminar embryo consists of three relatively flat layers of ectoderm, endoderm (also known as "entoderm") and mesoderm.

As the embryo develops, the mesoderm starts to segment into three main regions: the paraxial mesoderm, the intermediate mesoderm and the lateral plate mesoderm.

The lateral plate mesoderm later splits in half to form two layers bounding a cavity known as the intraembryonic coelom. Collectively, both layers are known as splanchnopleure. Individually, each are known as visceropleure and somatopleure.
* The "visceropleure" is associated with the underlying endoderm which it is in contact with, and later becomes the serous membrane in contact with visceral organs within the body.
* The "somatopleure" is associated with the overlying ectoderm and later becomes the serous membrane in contact with the body wall.

The intraembronic coelom can now be seen as a cavity within the body which is covered with serous membrane derived from the splanchnopleure. This cavity is divided and demarcated by the folding and development of the embryo, ultimately forming the serous cavities which house many different organs within the thorax and abdomen.



External links

* - "Tissues, Layers, and Organs: transverse section of rat gut"
* - "Uterus"
* - "Jejunum"

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Look at other dictionaries:

  • serous membrane — n any of various thin membranes (as the peritoneum, pericardium, or pleurae) that consist of a single layer of thin flat mesothelial cells resting on a connective tissue stroma, secrete a serous fluid, and usu. line bodily cavities or enclose the …   Medical dictionary

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  • serous membrane — n. the thin membrane lining most of the closed cavities of the body and folded back over the enclosed organs, as the peritoneum or pericardium …   English World dictionary

  • serous membrane — serosa a smooth transparent membrane, consisting of mesothelium and underlying elastic fibrous connective tissue, lining certain large cavities of the body. The peritoneum of the abdomen, pleura of the chest, and pericardium of the heart are all… …   The new mediacal dictionary

  • serous membrane — noun a thin membrane lining the closed cavities of the body; has two layers with a space between that is filled with serous fluid • Syn: ↑serosa • Hypernyms: ↑membrane, ↑tissue layer • Hyponyms: ↑pleura, ↑peritoneum …   Useful english dictionary

  • serous membrane — noun Date: 1813 a thin membrane (as the peritoneum) with cells that secrete a serous fluid; especially serosa …   New Collegiate Dictionary

  • serous membrane — noun A thin membrane that secretes serum lining an internal body cavity, such as the peritoneum, the pericardium, and the pleura. Syn: serosa, serous tunic …   Wiktionary

  • serous membrane — Anat., Zool. any of various thin membranes, as the peritoneum, that line certain cavities of the body and exude a serous fluid. Also called serosa. [1865 70] * * * …   Universalium

  • serous membrane — se′rous mem′brane n. anat. zool. zool. any of various thin membranes, as the peritoneum, that line certain cavities of the body and exude a serous fluid Also called serosa • Etymology: 1865–70 …   From formal English to slang

  • serous membrane — /sɪərəs ˈmɛmbreɪn/ (say searruhs membrayn) noun any of various thin membranes, as the peritoneum, which line certain cavities of the body and exude a serous fluid …  

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