TABLE 1.

Common stains used in assessing osteogenesis and angiogenesis.

Stain	Target	Description
Haematoxylin	Stains nuclei blue	Stains the chromatin in cell nuclei dark blue. Also stains rough endoplasmic reticulum, ribosomes, collagen, myelin, elastic fibers, and mucins.
Eosin	Stains cytoplasm pink	Often used as a counterstain with haematoxylin, together known as H&E. Stains cytoplasm pink.
Masson’s trichrome	Stains collagen blue/green	Variable three color staining depending on the specific application of the stain. Usually produces: blue/green collagen; red keratin and muscle fibers; pink cytoplasm and black nuclei.
Toluidine blue	Stains proteoglycans and glycosaminoglycans purple	Stain color is produced by metachromasia. High affinity for DNA and RNA which are stained blue. Stains proteoglycans and glycosaminoglycans purple.
Van Gieson	Stains collagen red	Combination of piric acid and acid fuchsin. Differentiates collagen from other connective tissue. Known as HvG when combined with haematoxylin and collagen will appear pink.
Alizarin Red S	Stains calcium orange/red	Used to locate tissues with high calcium content such as bone
Calcein	Binds to calcium ions	Fluoresces green with excitation/emission wavelengths 488 nm/520 nm, respectively.
Tetracycline	Binds to calcium	Fluoresces yellow with excitation/emission wavelengths 450–490 nm/529 nm. Localizes to sites of active mineralization.