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The mesothelium is a membrane that forms the lining of several body cavities: the pleura (thoracal cavity), peritoneum
Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
 (abdominal cavity including the mesentery) and pericardium
Pericardium

The pericardium is a double-walled sac that contains the heart and the roots of the great vessels....
 (heart sac). Mesothelial tissue also surrounds the male internal reproductive organs (the tunica vaginalis testis) and covers the internal reproductive organs of women (the tunica serosa uteri). Mesothelium that covers the internal organs is called visceral mesothelium, while the layer that covers the body walls is called the parietal
Parietal

Parietal may refer to:*Parietal lobe of the brain*Parietal bone of the skull*Parietal scales of a snake lie in the general region of the parietal bone....
 mesothelium.

thelium derives from the embryo
Embryo

An embryo is a multicellular organism ploidy eukaryote in its earliest stage of development, from the time of first cell division until birth, Egg , or germination....
nic mesoderm
Germ layer

A germ layer is a group of cell s, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sea sponge produce two or three primary tissue layers ....
 cell layer, that lines the coelom
Body cavity

By the broadest definition, a body cavity is any fluid filled space in a multicellular organism. However, the term usually refers to the space, located between an animal?s outer covering and the outer lining of the gut cavity, where internal organs develop....
 (body cavity) in the embryo.






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The mesothelium is a membrane that forms the lining of several body cavities: the pleura (thoracal cavity), peritoneum
Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
 (abdominal cavity including the mesentery) and pericardium
Pericardium

The pericardium is a double-walled sac that contains the heart and the roots of the great vessels....
 (heart sac). Mesothelial tissue also surrounds the male internal reproductive organs (the tunica vaginalis testis) and covers the internal reproductive organs of women (the tunica serosa uteri). Mesothelium that covers the internal organs is called visceral mesothelium, while the layer that covers the body walls is called the parietal
Parietal

Parietal may refer to:*Parietal lobe of the brain*Parietal bone of the skull*Parietal scales of a snake lie in the general region of the parietal bone....
 mesothelium.

Origin

Mesothelium derives from the embryo
Embryo

An embryo is a multicellular organism ploidy eukaryote in its earliest stage of development, from the time of first cell division until birth, Egg , or germination....
nic mesoderm
Germ layer

A germ layer is a group of cell s, formed during animal embryogenesis. Germ layers are particularly pronounced in the vertebrates; however, all animals more complex than sea sponge produce two or three primary tissue layers ....
 cell layer, that lines the coelom
Body cavity

By the broadest definition, a body cavity is any fluid filled space in a multicellular organism. However, the term usually refers to the space, located between an animal?s outer covering and the outer lining of the gut cavity, where internal organs develop....
 (body cavity) in the embryo. It develops into the layer of cells that covers and protects most of the internal organs of the body.

Structure

The mesothelium forms a monolayer of flattened squamous-like epithelial cells resting on a thin basement membrane
Basement membrane

The basement membrane is a sheet of cells and fibers that covers two other kinds of cells -- the epithelium, which lines the cavities and surfaces of organs, and the endothelium, which lines the interior surface of blood vessels....
 supported by connective tissue
Connective tissue

Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
. Cuboidal mesothelial cells may be found at areas of injury, the milky spots of the omentum
Omentum

Omentum can refer to two different components of the peritoneum:* greater omentum* lesser omentum...
, and the peritoneal side of the diaphragm
Thoracic diaphragm

In the anatomy of mammals, the thoracic diaphragm is a sheet of muscle extending across the bottom of the ribcage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in Respiration ....
 overlaying the lymphatic lacunae. The luminal surface is covered with microvilli. The proteins and serosal fluid trapped by the microvilli provide a frictionless surface for internal organs to slide past one another.

Function

The mesothelium is composed of an extensive monolayer of specialized cells (mesothelial cells) that line the body's serous cavities and internal organs. The main purpose of these cells is to produce a lubricating fluid that is released between layers, providing a slippery, non-adhesive and protective surface to facilitate intracoelomic movement.

The mesothelium is also implicated in the transport and movement of fluid and particulate matter across the serosal cavities, leukocyte migration in response to inflammatory mediators, synthesis of pro-inflammatory cytokines, growth factors and extracellular matrix
Extracellular matrix

In biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal Cell in addition to performing various other important functions....
 proteins to aid in serosal repair, and the release of factors to promote the disposition and clearance of fibrin
Fibrin

Fibrin is a fibrous protein involved in the clotting of blood, and is non globular. It is a fibrillar protein that is Polymerization to form a "mesh" that forms a hemostasis plug or clot over a wound site....
 (such as plasminogen). It is an antigen presenting cell. Furthermore, the secretion of glycosaminoglycans and lubricants may protect the body against infection and tumor dissemination.

Role in disease

  • Mesothelioma
    Mesothelioma

    Mesothelioma is a form of cancer that is almost always caused by previous exposure to asbestos. In this disease, malignant Cell develop in the mesothelium, a protective lining that covers most of the body's internal organs....
    :     (cancer
    Cancer

    Cancer is a class of diseases in which a group of cell display uncontrolled growth , invasion , and sometimes metastasis . These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, do not invade or metastasize....
     of the mesothelium) is a disease in which cells of the mesothelium become abnormal and divide without control or order. They can invade and damage nearby tissues and organs. Cancer cells can also metastasize (spread) from their original site to other parts of the body. Most cases of mesothelioma begin in the pleura or peritoneum. More than 90% of mesothelioma cases are linked to asbestos
    Asbestos

    Asbestos is a naturally occurring silicate mineral with long, thin fibrous crystals. The word asbestos is derived from a Greek language adjective meaning inextinguishable....
     exposure.


  • Intra-abdominal adhesions: Normally, the mesothelium secretes plasminogen, which removes fibrin
    Fibrin

    Fibrin is a fibrous protein involved in the clotting of blood, and is non globular. It is a fibrillar protein that is Polymerization to form a "mesh" that forms a hemostasis plug or clot over a wound site....
     deposits. During surgical procedures, the mesothelium may be damaged. Its fibrinolytic capacity becomes insufficient and fibrin accumulates, causing fibrous adhesions between opposing surfaces. These adhesions cause intestinal obstruction and female infertility if it occurs in the abdomen, and may impair cardiac and lung function in the thorax.


  • Ultrafiltration failure: The peritoneal mesothelium is implicated in the long-term development of ultrafiltration failure in peritoneal dialysis
    Peritoneal dialysis

    Introduction Current treatment options for patients with severe chronic kidney failure are dialysis and kidney transplantation. Dialysis is a treatment that removes substances such as water, salts, and waste products , which build up in patients with failing kidneys....
     patients. The presence of supra-physiological glucose concentrations, acidity, and glucose degradation products in peritoneal dialysis fluids contribute to the fibrosis
    Fibrosis

    Fibrosis is the formation or development of excess fibrous connective tissue in an organ or tissue as a reparative or reactive process, as opposed to a formation of fibrous tissue as a normal constituent of an organ or tissue....
     of the peritoneal mesothelium, either by epithelial-mesenchymal transition
    Epithelial-mesenchymal transition

    Epithelial-mesenchymal transition is a program of development of biological cell characterized by loss of cell adhesion, repression of cadherin expression, and increased cell mobility....
     or increased proliferation of existing fibroblasts. A fibrosed peritoneum results in the increased passage of solutes across the peritoneum and ultrafiltration failure.


Sources

  • (National Cancer Institute
    National Cancer Institute

    The National Cancer Institute is part of the United States Federal government's National Institutes of Health. The NCI is a federally funded research and development center, one of eight agencies that compose the United States Public Health Service in the United States Department of Health and Human Services....
    ).
"Mesothelium" - "Tissues, Layers, and Organs: transverse section of rat gut"
  • Mutsaers SE. "Mesothelial cells: Their structure, function, and role in serosal repair." Respirology 2002; 7:171-191