Mesothelium

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Mesothelium
Cytology of normal mesothelium.jpg
Cytology of normal mesothelial cells, with typical features. [1] Wright's stain
Histology of the mesothelial lining of a hernia sac.jpg
Histology of the peritoneal mesothelial lining, and underlying fibrous tissue. H&E stain.
Details
Precursor Somatopleuric mesenchyme
Identifiers
Latin mesothelium
TH H2.00.02.0.02017, H3.04.08.0.00003
FMA 14074
Anatomical terminology

The mesothelium is a membrane composed of simple squamous epithelial cells of mesodermal origin, [2] which forms the lining of several body cavities: the pleura (pleural cavity around the lungs), peritoneum (abdominopelvic cavity including the mesentery, omenta, falciform ligament and the perimetrium) and pericardium (around the heart).

Contents

Mesothelial tissue also surrounds the male testis (as the tunica vaginalis) and occasionally the spermatic cord (in a patent processus vaginalis). Mesothelium that covers the internal organs is called visceral mesothelium, while one that covers the surrounding body walls is called the parietal mesothelium. The mesothelium that secretes serous fluid as a main function is also known as a serosa.

Origin

Mesothelium derives from the embryonic mesoderm cell layer, that lines the coelom (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 supported by dense irregular connective tissue. Cuboidal mesothelial cells may be found at areas of injury, the milky spots of the omentum, and the peritoneal side of the diaphragm overlaying the lymphatic lacunae. The luminal surface is covered with microvilli. The proteins and serosal fluid trapped by the microvilli provide a slippery surface for internal organs to slide past one another.

Function

Micrograph of benign mesothelial cells. Peritoneal wash. Pap stain. Mesothelium peritoneal wash high mag.jpg
Micrograph of benign mesothelial cells. Peritoneal wash. Pap stain.
Cytology of reactive mesothelium, with typical features. The main causes of reactive mesothelium are infection, trauma and cancer. Wright's stain. Cytology of reactive mesothelium.jpg
Cytology of reactive mesothelium, with typical features. The main causes of reactive mesothelium are infection, trauma and cancer. Wright's stain.

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, [4] providing a slippery, non-adhesive, and protective surface to facilitate intracoelomic movement.

A layer of mesothelial cells grown in cell culture, featuring the typical "cobblestone" appearance. L12 IL-1 48hr 0ng.jpg
A layer of mesothelial cells grown in cell culture, featuring the typical "cobblestone" appearance.

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 proteins to aid in serosal repair, and the release of factors to promote the disposition and clearance of fibrin (such as plasminogen). Mesothelial cells are capable of phagocytosis and are antigen-presenting cells. The secretion of glycosaminoglycans and lubricants may protect the body against infection and tumor dissemination.

Role in disease

See also

Related Research Articles

<span class="mw-page-title-main">Peritoneum</span> Serous membrane that forms lining of abdominal cavity or coelom

The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal organs, and is composed of a layer of mesothelium supported by a thin layer of connective tissue. This peritoneal lining of the cavity supports many of the abdominal organs and serves as a conduit for their blood vessels, lymphatic vessels, and nerves.

<span class="mw-page-title-main">Abdominal cavity</span> Body cavity in the abdominal area

The abdominal cavity is a large body cavity in humans and many other animals that contain organs. It is a part of the abdominopelvic cavity. It is located below the thoracic cavity, and above the pelvic cavity. Its dome-shaped roof is the thoracic diaphragm, a thin sheet of muscle under the lungs, and its floor is the pelvic inlet, opening into the pelvis.

<span class="mw-page-title-main">Body cavity</span> Internal space within a multicellular organism

A body cavity is any space or compartment, or potential space, in an animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid.

<span class="mw-page-title-main">Pleural cavity</span> Thin fluid-filled space between the two pulmonary pleurae (visceral and parietal) of each lung

The pleural cavity, pleural space, or interpleural space is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication between the membranes, and also to create a pressure gradient.

<span class="mw-page-title-main">Pericardium</span> Double-walled sac containing the heart and roots of the great vessels

The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong inelastic connective tissue, and an inner layer made of serous membrane. It encloses the pericardial cavity, which contains pericardial fluid, and defines the middle mediastinum. It separates the heart from interference of other structures, protects it against infection and blunt trauma, and lubricates the heart's movements.

<span class="mw-page-title-main">Epithelium</span> Tissue lining the surfaces of organs in animals

Epithelium or epithelial tissue is a thin, continuous, protective layer of compactly packed cells with a little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. Epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. These tissues also lack blood or lymph supply. The tissue is supplied by nerves.

<span class="mw-page-title-main">Mesothelioma</span> Cancer associated with asbestos

Mesothelioma is a type of cancer that develops from the thin layer of tissue that covers many of the internal organs. The area most commonly affected is the lining of the lungs and chest wall. Less commonly the lining of the abdomen and rarely the sac surrounding the heart, or the sac surrounding the testis may be affected. Signs and symptoms of mesothelioma may include shortness of breath due to fluid around the lung, a swollen abdomen, chest wall pain, cough, feeling tired, and weight loss. These symptoms typically come on slowly.

<span class="mw-page-title-main">Mesentery</span> Contiguous fold of tissues that supports the intestines

The mesentery is an organ that attaches the intestines to the posterior abdominal wall and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines, among other functions.

The peritoneal cavity is a potential space between the parietal peritoneum and visceral peritoneum. The parietal and visceral peritonea are layers of the peritoneum named depending on their function/location. It is one of the spaces derived from the coelomic cavity of the embryo, the others being the pleural cavities around the lungs and the pericardial cavity around the heart.

<span class="mw-page-title-main">Serous membrane</span> Smooth coating lining contents & inner walls of body cavities

The serous membrane is a smooth tissue membrane of mesothelium lining the contents and inner walls of body cavities, which secrete serous fluid to allow lubricated sliding movements between opposing surfaces. The serous membrane that covers internal organs is called visceral, while the one that covers the cavity wall is called parietal. For instance the parietal peritoneum is attached to the abdominal wall and the pelvic walls. The visceral peritoneum is wrapped around the visceral organs. For the heart, the layers of the serous membrane are called parietal and visceral pericardium. For the lungs they are called parietal and visceral pleura. The visceral serosa of the uterus is called the perimetrium. The potential space between two opposing serosal surfaces is mostly empty except for the small amount of serous fluid.

<span class="mw-page-title-main">Adventitia</span> Outer layer of fibrous tissue surrounding a bodily organ

The adventitia is the outer layer of fibrous connective tissue surrounding an organ.

In physiology, serous fluid or serosal fluid is any of various body fluids resembling serum, that are typically pale yellow or transparent and of a benign nature. The fluid fills the inside of body cavities. Serous fluid originates from serous glands, with secretions enriched with proteins and water. Serous fluid may also originate from mixed glands, which contain both mucous and serous cells. A common trait of serous fluids is their role in assisting digestion, excretion, and respiration.

<span class="mw-page-title-main">Tunica vaginalis</span> Pouch of serous membrane that covers the testes

The tunica vaginalis is a pouch of serous membrane within the scrotum that lines the testis and epididymis, and the inner surface of the scrotum. It is the outermost of the three layers that constitute the capsule of the testis, with the tunica albuginea of penis situated beneath it.

<span class="mw-page-title-main">Adhesion (medicine)</span> Medical condition

Adhesions are fibrous bands that form between tissues and organs, often as a result of injury during surgery. They may be thought of as internal scar tissue that connects tissues not normally connected.

<span class="mw-page-title-main">Perimetrium</span>

The perimetrium is the outer serosal layer of the uterus, derived from the peritoneum overlying the uterine fundus, and can be considered a visceral peritoneum. It consists of a superficial layer of mesothelium, and a thin layer of loose connective tissue beneath it.

The development of the gonads is part of the prenatal development of the reproductive system and ultimately forms the testicles in males and the ovaries in females. The gonads initially develop from the mesothelial layer of the peritoneum.

Coelomic epithelium refers to the epithelium that lines the surface of the body wall and abdominal organs. It constitutes the outermost layer of the male and female gonads, thus forming the germinal epithelium of the female or of the male. It is also called the germinal epithelium of Waldeyer or sometimes the superficial epithelial cells in embryology. It is often encountered in the medical setting as an important source of various types of ovarian cancer, primary peritoneal serous cancer and endometriosis. ,

<span class="mw-page-title-main">Peritoneal mesothelioma</span> Medical condition

Peritoneal mesothelioma is the name given to the cancer that attacks the lining of the abdomen. This type of cancer affects the lining that protects the contents of the abdomen and which also provides a lubricating fluid to enable the organs to move and work properly.

<span class="mw-page-title-main">Pulmonary pleurae</span> Serous membrane that lines the wall of the thoracic cavity and the surface of the lung

The pulmonary pleurae are the two opposing layers of serous membrane overlying the lungs, mediastinum and the inside surfaces of the surrounding chest walls.

A tissue membrane is a thin layer or sheet of cells that covers the outside of the body, the organs, internal passageways that lead to the exterior of the body, and the lining of the moveable joint cavities. There are two basic types of tissue membranes: connective tissue and epithelial membranes.

References

  1. Image by Mikael Häggström, MD. Sources for mentioned features:
    - "Mesothelial cytopathology". Libre Pathology. Retrieved 2022-10-18.
    - Shidham VB, Layfield LJ (2021). "Introduction to the second edition of 'Diagnostic Cytopathology of Serous Fluids' as CytoJournal Monograph (CMAS) in Open Access". CytoJournal. 18: 30. doi:10.25259/CMAS_02_01_2021. PMC   8813611 . PMID   35126608.
  2. Victor P. Eroschenko (2008). Di Fiore's atlas of histology with functional correlations. Lippincott Williams & Wilkins. pp. 31–. ISBN   978-0-7817-7057-6 . Retrieved 28 May 2011.
  3. Image by Mikael Häggström. MD.
    Reference for findings and causes: "Reactive Mesothelial Cells". LabCE.
  4. Leopold G. Koss; Myron R. Melamed (2006). Koss' diagnostic cytology and its histopathologic bases. Lippincott Williams & Wilkins. pp. 124–. ISBN   978-0-7817-1928-5 . Retrieved 28 May 2011.