br Conflict of interest br Introduction Histopathology invol
Conflict of interest
Introduction Histopathology involves the use of dyes for microscopic examination of tissues in part to spot signs and characteristic features of diseases. Recently, computer assisted diagnosis (CAD) has been widely used in developed countries. In general, it is well-recognised that the importance of quantitative analysis in histopathology cannot be overemphasized, particularly because most pathology diagnoses are based on the subjective opinion of pathologists. The utilization of CAD has the potential to improve the practice of histopathology and other related discipline in different ways. With the influx of different imaging technologies, histological images of diverse staining techniques including immunehistochistry are produced for either manual or automated analysis. Generally, such images are better obtained at low magnification. ImageJ, which is a public domain, Java-based image processing program developed at the National Institute of Health, is used in quantitative analysis of histological stains on tissues, among other functions. Although the human eye is sensitive to a number of factors, including luminosity and variation in harpagoside and brightness, critical visual analysis is open to subjective interpretation. The essence of morphometry is to eliminate subjectivity and increase the reproducibility of measurements. The quantification of percentage area covered by different stains on different tissues as well as the intensity measurement have not been given due attention, a situation that has resulted in the lack of improvement in routine staining procedures. Advances in computer image analysis techniques allow more accurate quantification of histopathological analysis. The mechanisms of tissue staining are histochemical in nature, which is the application of chemical substances onto a tissue in order to produce a visible outcome. To achieve this reaction, the tissue takes up the stain either through a chemical or physical method (adsorption, absorption, solubility, osmotic pressure or capillary attraction). The type and nature of this uptake may differ from one tissue to another, as well as by the technique employed. There are two groups of dyes commonly used: 1) the natural group of dyes, which are derived from plants and insects, 2) the synthetic dyes, which are derived from coal tar. These groups of dyes can be applied regressively (differentiation), progressively (without differentiation) or directly (without the use of mordant). The importance of histopathological staining cannot be overemphasized, especially as the process allows for adequate and reliable histological results to be obtained. Hence, in this study, we investigated the use of morphometric quantitative image analysis as a tool to aid in the diagnosis of stained lesions using seven staining techniques.
Materials and methods
Discussion The % area of the tissue covered by stain as well as the intensity is dependent on the type of stain and tissue. Stain uptake is often due to dye-tissue or reagent-tissue affinities, permeability and pore size. MT covered a greater % area with a high intensity measurement for most tissues compared to other type of staining methods used in our study. This was reflected in the outcome of the flow chart (Fig. 3), where it was observed that VVG, PTAH and MT occupied a larger surface area than SGM, PAS and H&E. MT was originally used for the demonstration of connective and mesenchymal tissues, with the ability to impact up to three colours to tissue and bind with collagen fibres. Suvarna et al. stated that smaller molecule dyes will stain any of the basic type of tissues. This is similar to the rule of trichrome staining, which states that a smaller dye molecule will penetrate and stain tissue element, but whenever a larger dye molecule can penetrate the same element, the smaller molecule will be displaced by it. Other factors that contribute to dye-tissue affinity include Coulombic attraction, which is also referred to as salt links or electrostatic bonds. Also, Van der Waals forces including intermolecular attractions, hydrogen bonding, covalent bonding, and the hydrophobic effect are among other contributing factors.