Mesothelial cells are a specialized type of cell that form a protective lining throughout the body. These cells play a fundamental role in maintaining the smooth operation and health of various internal structures. They contribute significantly to the body’s internal environment, enabling organs to function without friction and providing a barrier against external threats.
What Are Mesothelial Cells?
Mesothelial cells are specialized epithelial cells that collectively form a membrane known as the mesothelium. This protective layer lines the body’s internal cavities and covers the organs within them, acting as a crucial interface. Specifically, mesothelial cells are found in the pleura (which surrounds the lungs), the peritoneum (lining the abdominal cavity and its organs), the pericardium (which encloses the heart), and the tunica vaginalis (a lining around the testes).
These cells appear as a single layer of flattened, plate-like structures. Their surface is covered with numerous finger-like projections called microvilli. These microvilli contribute to the cell’s surface area and help trap serous fluid, a lubricating substance. Below this single layer of cells is a thin basement membrane, supported by connective tissue.
How Mesothelial Cells Function
Mesothelial cells perform several functions that protect internal organs. Their primary role involves lubrication, which is achieved by secreting serous fluid. This fluid, known as serous fluid, creates a slippery surface, allowing organs like the lungs, heart, and abdominal organs to glide against each other during movements such as breathing or digestion. The microvilli on the cell surface help to retain this fluid, reducing friction.
Mesothelial cells also regulate fluid transport and regulation within body cavities. They act as a semi-permeable membrane, controlling fluid in spaces like the pleural cavity around the lungs or the peritoneal cavity in the abdomen, maintaining appropriate fluid levels. This regulation is important for both lubrication and nutrient exchange.
These cells contribute to the body’s immune response and tissue repair. They can trigger inflammatory responses to pathogens by recognizing microbial components. They release inflammatory mediators and chemokines, which help recruit immune cells to the site of injury or infection. These cells participate in tissue repair following inflammation, aiding in coagulation and preventing adhesions between organs.
Mesothelial Cells and Health Concerns
Mesothelial cells can react to various forms of irritation or inflammation, leading to changes in their appearance and function. Such reactive changes are often a normal response to underlying issues like infection or trauma. While these cells can generally repair damaged tissue, prolonged irritation can sometimes lead to more serious conditions.
The most significant health concern directly linked to mesothelial cells is malignant mesothelioma, a rare and aggressive cancer. This cancer originates from these cells, most commonly in the pleura surrounding the lungs, but it can also occur in the peritoneum of the abdomen or, less frequently, around the heart or testes. The primary cause of malignant mesothelioma is prolonged exposure to asbestos fibers, which can damage the DNA of mesothelial cells and lead to uncontrolled growth.
When mesothelial cells become cancerous, they can produce an excessive amount of fluid, leading to fluid accumulation in the affected body cavity. For instance, in pleural mesothelioma, this can result in a pleural effusion, where fluid builds up around the lungs, making breathing difficult and causing chest pain. Similarly, in peritoneal mesothelioma, fluid buildup is known as ascites or peritoneal effusion. The presence of an abnormally high number of mesothelial cells, particularly those showing malignant changes, in fluid samples can indicate a serious underlying problem, including mesothelioma.