What Is A Trichrome
The pedantic meaning of trichrome is three coloured. Apart from that there is no clear definition of what constitutes this kind of staining technique. A good basis for comparison is Masson's methods, but even this does not clarify the term since in some variants he used three dyes, and in others he used only two. Some people consider the nuclear stain as one of the colours, others do not.
Since counting colours is rather pointless, the term trichrome is used in StainsFile to include any staining technique meeting the following criteria:–
These criteria exclude the picro-fuchsin variants, and those methods incorporating two or more acid dyes at a low pH, but in which the acid present is for pH adjustment. These techniques are grouped under the heading: Picro-fuchsin and related methods.
It does not include methods which apply a large molecular weight yellow dye in an anhydrous solvent. These are grouped under the heading: Yellowsolve Methods.
The criteria does include methods which demonstrate tissue components other than collagen and muscle. This includes methods for fibrin and pituitary cells, and those incorporating the demonstration of elastic with dyes such as orcein. These latter methods are often called tetrachrome or polychrome methods, but for convenience are included with the trichrome methods.