Staining of the extracellular matrix
The extracellular matrix of the spaces between the cells becomes also stained by the usual histological stains.
Its chemical composition varies in the different tissues and regions of the body. In places where the matrix is composed mainly of proteins, it will be stained mainly with eosin. This was already shown on last page 1-24, where collagen fibers were stained by eosin.
The image on this page is of a hyaline cartilage.
Observe that instead of being acidophilic (pink, stained by eosin) as the collagen-rich matrix, the cartilage extracellular matrix is stained blue-purple by hematoxylin and is, therefore, basophilic.
This happens because this matrix contains many molecules with acidic groups (mainly sulfate groups), that have affinity for hematoxylin.
After moving the mouse or clicking over the image: the nuclei of the cartilage cells (chondrocytes) are seen in dark blue and the extracellular matrix in turquoise blue.
The cartilage of the image is surrounded at its left and right borders by connective tissue composed of cells surrounded by a collagen-rich extracellular matrix. Collagen stains red or pink by eosin and is acidophilic. The connective tissue will be seen in pink after moving the mouse.
Hyaline cartilage. Staining: hematoxylin and eosin. Medium magnification.
