Laboratory Procedures and Management
Jeremy R. Jass in Understanding Pathology, 2020
The solution into which tissue samples are placed usually includes formaldehyde. First introduced in 1893 (Bracegirdle, 1993), formaldehyde penetrates tissues rapidly and alters the structure of molecules so that all biological activity is destroyed. In particular, enzymes are denatured. This is important, because dying tissues would normally release their own enzymes and digest themselves, a process called autolysis. Dying tissues are also colonised by bacteria, but these are also destroyed by formaldehyde. Formaldehyde thereby preserves normal cellular structure and acts as a mordant, i.e. it facilitates the subsequent staining of the tissues with dyes. The entire process is called tissue fixation (since it attempts to ‘fix’ tissue in a lifelike state) and takes a few hours to a day or two, depending on the size of the specimen. Fixation can be speeded up by microwaving the tissue.
Symptom flowcharts and testing guidelines
Sarah Bekaert, Alison White in Integrated Contraceptive and Sexual Healthcare, 2018
Staining bottles containing:– crystal violet (the primary stain)– iodine solution (the mordant by forming a crystal violet-iodine complex)– decolouriser (ethanol is a good choice)– safranin (the counterstain)– water (preferably in a squirt bottle or from a specified tap).
Ethnobotany of Useful Plants in Indo-Gangetic Plain and Central India
T. Pullaiah, K. V. Krishnamurthy, Bir Bahadur in Ethnobotany of India, 2017
The making of natural dye is one of the oldest known to man and dates back to the dawn of human civilization. Color on clothing has been extensively used since 5000 years back (Kar and Borthakur, 2008). It was practice during the Indus river valley civilization at Mohenjodaro and Harappa (3500 BC), former Egyptian and China period (Siva, 2007). Moldenke and Moldenke (1983) reports that an orange or yellow impermanent dye is made from corolla tubes of Nyctanthes arbortristis Linn. for Buddhist robes in Sri Lanka (Panigrahi and Murti, 1989-1999). In the making of natural dyes the uses of mordant to hold fast the dye and to prevent them from touching the cloth were printed bales of soft textile. In India there are more than 450 plants out of 17,000 plants have been recorded that can produce dye. In 19th century the discovery of synthetic dyes has been dealt a massive blow to Indian textile industry. Research has been shown that the vast uses of synthetic dyes associated with hazards effecting human body system; it causes skin cancer, temporary or permanent blindness and also the respiratory system, etc. (Dubey, 2007; Singh, 2001).
Evaluation of different haematoxylin stain subtypes for the optimal microscopic interpretation of cutaneous malignancy in Mohs frozen section histological procedure
Published in British Journal of Biomedical Science, 2021
JA Gabriel, M Shams, GE Orchard
As a part of the Mohs procedure, H&E staining remains the staple method for microscopic evaluation for pathological diagnosis and interpretation of these tumour types. In most cases, the haematoxylin nuclear staining plays an essential role in determining neoplastic disease. The presence of basophilic, hyperchromatic nuclei, apoptotic bodies, mitotic figures and pleomorphism all rely on clear staining to allow the generation of unequivocal diagnoses. The haematoxylin dye is extracted from the bark of the logwood tree Haematoxylin Campechianum, originally located in the Mexican state Campeche [6]. The conversion of haematoxylin to haematin, vital for its ability to bind to nuclear components, is aided by the use of mordants. There are a broad range of mordants which can impact the tissue components stained and colour of staining, which is visualised. The mordants are usually a metal cation such as iron, aluminium, molybdenum, lead and tungsten [7].
Haematoxylin – the story of the blues
Published in British Journal of Biomedical Science, 2018
Prior to this time, during the Elizabethan era, early fabric dyers in England found the colours of haematoxylin to be ‘fugitive’. Even colourisation of hands and shirt collars was readily removed from those working with the dye. As a result and due to the dye’s lack of permanency, an Elizabethan prohibition followed which lasted nearly a century. This paved the way for the introduction of the mordant, which imparted a long-lasting permanency for the dye. The extracted haematoxylin was extracted and subsequently oxidised in boiling water to form hematein. The hematein is a complex phenolic compound similar to flavonoid pigments of flowers. There are two basic procedures which convert the haematoxylin to hematein, natural oxidation (‘ripening’) by exposure to light and air or alternatively chemical oxidation employing either sodium iodate or mercuric oxide and potassium permanganate. The chemical method is much faster and results in instantaneous oxidation.