RESIDENT CELLS OF THE CONNECTIVE TISSUE
MAST CELL
The mast cells, also called mastocytes, are large, round or oval-shaped cells that are often found close to blood vessels.
They participate in inflammatory and allergic reactions by releasing several biologically active substances, including histamine and heparin that are stored in numerous cytoplasmic vacuoles called granules.
The nucleus is usually located near the center of the cell, and the cytoplasm contains many clearly defined granules. However, these granules are usually not well stained by routine hematoxylin and eosin (H&E) staining. For this reason, mast cells are often difficult to recognize in routinely stained histological sections. They can be identified with metachromatic dyes, such as toluidine blue, which stain their granules very well and with stains used to visualize elastic fibers, such as Weigert’s stain.
Metachromatic dyes are so called because they stain cellular structures a color slightly different from the original color of the dye. Mast cell granules, for example, stain purple instead of blue by toluidine blue.
The image is of a whole-mount preparation of a small piece of a mesentery that was stained to demonstrate elastic fibers. The mast cell nucleus is not stained, but its cytoplasm is filled with granules.
The thin fibrils are elastic fibers of the extracellular matrix.
They participate in inflammatory and allergic reactions by releasing several biologically active substances, including histamine and heparin that are stored in numerous cytoplasmic vacuoles called granules.
The nucleus is usually located near the center of the cell, and the cytoplasm contains many clearly defined granules. However, these granules are usually not well stained by routine hematoxylin and eosin (H&E) staining. For this reason, mast cells are often difficult to recognize in routinely stained histological sections. They can be identified with metachromatic dyes, such as toluidine blue, which stain their granules very well and with stains used to visualize elastic fibers, such as Weigert’s stain.
Metachromatic dyes are so called because they stain cellular structures a color slightly different from the original color of the dye. Mast cell granules, for example, stain purple instead of blue by toluidine blue.
The image is of a whole-mount preparation of a small piece of a mesentery that was stained to demonstrate elastic fibers. The mast cell nucleus is not stained, but its cytoplasm is filled with granules.
The thin fibrils are elastic fibers of the extracellular matrix.
Whole mount of mesentery. Staining: Weigert. Large magnification.