RESIDENT CELLS OF THE CONNECTIVE TISSUE
MACROPHAGE-1
Macrophages are cells derived from the monocytes, a type of blood leukocyte produced in the hematopoietic bone marrow.
Circulating monocytes can leave the blood by crossing the walls of blood vessels. After entering the tissues they develop into macrophages. They are often present in the connective tissue all over the body (not including the central nervous system). They become specially concentrated in various organs such as the liver, spleen, and lymph nodes.
Macrophages are specialized for phagocytosis and play an important role in the body’s defense. Together with the neutrophils they are considered “professional phagocytes” as compared to other cells that phagocyte occasionally or infrequently.
Furthermore, the macrophages contains many lysosomes which are important for digesting the material they engulf. They secrete several molecules that play important roles in the inflammatory process and the immune response
Macrophages are spherical or flattened, depending on the place where the are settled. They are relatively large cells when compared to red blood cells or lymphocytes
The cytoplasm of the macrophages stains pink with eosin and its spherical nucleus may be sometimes eccentric (meaning it is placed ouside of the cell center).
Recognizing a macrophage is not always easy in routine H&E-stained preparations. Immunocytochemical techniques can better identify them using specific antibodies or protein markers.
Another useful clue for identifying macrophages in tissue sections is to look for phagocytosed material within their cytoplasm. This is particularly helpful when examining isolated cells in connective tissue or in organs where macrophages are commonly found.
The image shows sections of the liver of a laboratory animal that had been injected intravenously with a solution containing the dye carmine. Macrophages in the liver, also known as Kupffer cells, phagocytosed particles of the dye. These particles can be seen within the cytoplasm of the cells, indicated by arrows.
Notice that macrophages that had engulfed large amounts of dye have their nuclei displaced toward the cell periphery. The accumulation of phagocytosed material occupies much of the cytoplasm and appears to “push” the nucleus toward the edge of the cell.
Circulating monocytes can leave the blood by crossing the walls of blood vessels. After entering the tissues they develop into macrophages. They are often present in the connective tissue all over the body (not including the central nervous system). They become specially concentrated in various organs such as the liver, spleen, and lymph nodes.
Macrophages are specialized for phagocytosis and play an important role in the body’s defense. Together with the neutrophils they are considered “professional phagocytes” as compared to other cells that phagocyte occasionally or infrequently.
Furthermore, the macrophages contains many lysosomes which are important for digesting the material they engulf. They secrete several molecules that play important roles in the inflammatory process and the immune response
Macrophages are spherical or flattened, depending on the place where the are settled. They are relatively large cells when compared to red blood cells or lymphocytes
The cytoplasm of the macrophages stains pink with eosin and its spherical nucleus may be sometimes eccentric (meaning it is placed ouside of the cell center).
Recognizing a macrophage is not always easy in routine H&E-stained preparations. Immunocytochemical techniques can better identify them using specific antibodies or protein markers.
Another useful clue for identifying macrophages in tissue sections is to look for phagocytosed material within their cytoplasm. This is particularly helpful when examining isolated cells in connective tissue or in organs where macrophages are commonly found.
The image shows sections of the liver of a laboratory animal that had been injected intravenously with a solution containing the dye carmine. Macrophages in the liver, also known as Kupffer cells, phagocytosed particles of the dye. These particles can be seen within the cytoplasm of the cells, indicated by arrows.
Notice that macrophages that had engulfed large amounts of dye have their nuclei displaced toward the cell periphery. The accumulation of phagocytosed material occupies much of the cytoplasm and appears to “push” the nucleus toward the edge of the cell.
Macrophages in the liver. Staining: hematoxylin. Large magnification.