Nowadays, a substance called ponceau S is often used as a substitute for acid fuchsin, as it is slightly more efficient. This causes collagen to be stained differently from muscle and red blood cells, allowing differentiation. Acid fuchsin has larger molecules, which penetrate collagen, displacing the picric acid molecules. However, they are only fully retained in red blood cells and muscle, as these have a fine, close texture. Picric acid molecules are very small, and therefore penetrate all types of tissues. Surrounding muscle tissues and blood cells are stained yellow. The stain uses a mixture of picric acid and acid fuchsin to penetrate the tissue sample, causing collagen to become red. It is often used to identify the characteristic arrangement of fibers in different types of tumours. The van Gieson stain is a very common stain used to highlight the difference between collagen and other connective tissue such as muscle tissues.

There are variety of special stains, a brief detail of some of them is given below. Special stains stain are used to identify and demonstrate particular structures and tissues which are not visualized by H&E stains.

The section is dehydrated with ethanol, and mounted using a resinous medium.

The excess stain is rinsed off with tap water.

The section is rinsed in tap water and then submerged in an acid-alcohol solution.

Progressive involves using a less concentrated dye, and checking it at intervals until the section is sufficiently stained Regressive involves over staining the section, and then rinsing away the excess.

Here there are 2 potential options - progressive or regressive.

It is then submerged in haematoxylin, the time in the stain varies according to the type, age of stain and on personal preferences.

The section is rehydrated and then cleared using xylene.

The general procedure of the H & E stain is as follows: Haematoxylin & Eosin stain of the loose connective tissue (histological slide) The most common stains used in histology are outlined in this article. They are rehydrated and then made translucent (cleared) using a clearing substance such as xylene, before being stained. For staining, paraffin sections of tissue are normally used. Certain stains change the coloration of cells and tissues significantly, different from the color of the original dye complex, a phenomenon known as metachromasia. A huge range of stains is used in histology, from dyes and metals to labeled antibodies.

Staining is widely used in histopathology and diagnosis, as it allows for the identification of abnormalities in cell count and structure under the microscope. Therefore staining is used to create differential coloration, allowing clearer observation and analysis of cells. When observing a tissue sample under the light microscope, it is often difficult to distinguish between different cells and tissue, as they are almost colorless. With the various staining methods we can visualise the different parts of the cells

Black light for stains