Why histology

This type of research may take place in a hospital laboratory but it is more often carried out in universities, research institutes and pharmaceutical companies. The conventional view of a histopathologist is someone looking down a microscope.

Most histological work does indeed involve the preparation of tissues for microscopy, observation of sections and reporting of the findings. However, a pathologist can often tell a great deal about a tissue without using a microscope.

For example, the brain of a person affected by multiple sclerosis has distinct lesions areas of damage or injury that are a few millimetres across. These are called plaques, and can readily be seen in a tissue sample with the human eye see the darker areas highlighted with arrows in Figure 1 below.

Such large specimens that can be examined macroscopically by eye are usually only available post-mortem after death or following surgical removal of tissue. In contrast, biopsy specimens, which consist of just a needleful of cells or a flake of tissue, can be extracted at any time, but can only be examined microscopically. In this course we will first teach you how to use a basic light microscope and then show some sections of various human tissues, presented via a virtual microscope, which mirrors the functions of a real microscope.

Once you are familiar with the normal appearance of different tissues, we will start to introduce sections from diseased tissues, and relate their appearance to the normal physiology of the tissue and pathological changes that have occurred. Note that the virtual microscope tool will work in all modern browsers on desktop computers, laptops and tablet devices. However, we recommend completing the course on a desktop computer or laptop for better viewing of the sections and to enable integration of microscopy with the course text, images and video in separate windows.

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Not ready for formal University study? Then browse over free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released. Every year, thousands of students decide to study with The Open University. Request an Open University prospectus Measure content performance. Develop and improve products. List of Partners vendors. The National Cancer Institute defines histopathology as "the study of diseased cells and tissues using a microscope.

So taken together, histopathology literally means the study of tissues as relates to disease. A histopathology report describes the tissue that has been sent for examination and the features of what the cancer looks like under the microscope. A histopathology report is sometimes called a biopsy report or a pathology report. The specialist doctor who does the examination under the microscope is called a pathologist.

The tissue that is studied comes from a biopsy or surgical procedure whereby a sample of the suspect tissue is selected and sent to the laboratory. It is then processed and cut into very thin layers called sections , stained, and examined under microscopes to characterize the details of the cells in the tissue. For some diseases, the surgeon can get a sample of the tissue interpreted very quickly through the use of frozen sections.

Frozen sections or slices are used sparingly in lymphoma, however, due to problems in interpretation and sampling. In lymphomas, lymph nodes are the tissue most commonly examined in histopathology. For many types of blood cancers, a bone marrow biopsy may also be required for a definitive diagnosis. Histopathology reports on surgical cancer specimens are getting more and more complex. They may include:. Molecular techniques refer to the ability to analyze cells and tissues at the molecular level, which is at the level of proteins, receptors , and the genes that code for these things.

Many of the findings from such examination of the tissues are linked to prognosis. Prognostic indicators may include tumor grade and extent of spread, and whether or not the cancer was removed with a margin of healthy cells surrounding it, or if there is evidence the cancer has spread beyond what was removed. Grading systems differ depending on the kind of cancer being graded, but generally, the cells are scored based on how abnormal they appear under the microscope, with Grade 1 tumors being more normal looking and Grade 4 tumors reflecting more abnormalities.

A high-grade tumor, then, is generally one in which the cells have more abnormalities. Grading is not the same as staging. Staging has more to do with where the cancer is found in the body and how far it has spread. In addition to the histopathology, other techniques may be used to assess the presence of cancer in the tissues, including fine needle aspiration cytology, and some of these techniques may be used more extensively in healthcare settings around the world.

Leukemias and lymphomas are diagnosed using a combination of their appearance:. Oftentimes in lymphomas and other cancers , a technique called immunohistochemistry is used to help assess the tumor type, prognosis, and treatment. Immunohistochemistry involves using antibodies to stick to particular tags or markers on the outside of the cancer cells. These markers that the antibodies stick to often have "CD" in their name, which stands for cluster of differentiation.

The results indicated that when comparing Hematoxylin and Eosin stain with S they? In addition, the use of the several staining methods aided in confirming results of earlier stain diagnosis. The literature review on staining techniques indicates that there has been great improvement in the histopathology and histotechnology. These staining techniques are still in use although several modifications have been made to improve their efficiency.

In other cases, some stain methods used earlier have been abandoned as they were toxic. Several staining techniques have been established to improve the staining methods. The histopathology lab today is laden with a great work load and different types of histological assignments Musumeci, In the history of histology, a great shift and development in histologic stains were shaped by improved technologic development of microscopes and the establishment of the histologic stains factory aniline dye in in Germany which manufactured variety of new-histological stains Godwin, It is during this time that the paraffin infiltration staining technique was devised Titford, While these changes have taken place, there are old stain procedures that are still in use today and many others have been replaced with new immunal or staining techniques.

Additionally, the complexity of stains has been enhanced for the purpose of efficient and consistent staining processes that show fine and differentiated tissues Ntziachristos, Histological staining is a commonly used medical process in pathological diagnosis and forensic studies.

The process of histological staining takes five key stages, and they include fixation, processing, embedding, sectioning and staining. Early histologists used the readily available chemicals to prepare tissues for microscopic studies; these laboratory chemicals were potassium dichromate, alcohol and the mercuric chloride to hard cellular tissues.

These fixatives and staining agents were ingenious and after a period colored staining agents were developed which are still applicable in the laboratory staining techniques today. Staining techniques used were; carmine, silver nitrate, Giemsa, Trichrome Stains, Gram Stain and Hematoxylin among others. There have been great changes in the techniques used for histological staining through chemical, molecular biology assays and immunological techniques collectively referred to us histochemistry and have facilitated greatly in the study of organs and tissues.

Hematoxylin is a basic dye that is commonly used in this process and stains the nuclei giving it a bluish color while eosin another stain dye used in histology stains the cell's nucleus giving it a pinkish stain Victor, While these changes have taken place, there are old stain procedures that are still in use today and many others have been replaced with new immunalstaining or staining techniques Sine, Similarly, there have been great changes in workload requiring more advanced technics of staining.

The case studies indicate that, in the modern histology a combination of different stain techniques are used to enhance the effectiveness of the staining process. In the modern histologic as a way of improving histological stains, several stains have been modified and combined with other stains to improve their effectiveness. National Center for Biotechnology Information , U. Glob J Health Sci. Published online Jun Author information Article notes Copyright and License information Disclaimer.

E-mail: moc. Received May 7; Accepted May This article has been cited by other articles in PMC. Abstract The history of histology indicates that there have been significant changes in the techniques used for histological staining through chemical, molecular biology assays and immunological techniques, collectively referred to as histochemistry. Keywords: histological staining, histology, histopathology, histochemistry. Introduction Histology is the microscopic study of animal and plant cell and tissues through staining and sectioning and examining them under a microscope electron or light microscope.

Specific Aspects of Histopathology 2. Methodology The research used an extensive exploration and review of historical, recent and current medical research studies and case studies in order to collect quantitative and qualitative data in regard to histological stains used in the past and recent cases Silverman, Literature Review 4.

Hematin and Hematoxylin These are naturally occurring substances that have been in use in the history of histopathology Titford, Silver Nitrate Silver Nitrate has had a long usage in historical staining techniques and is still used in modern pathology. Romanowsky Stains—Giemsa Stains They were developed in the by Dimitri Romanowsky and popular for its multicolor in identifying blood parasites. Gram Stain The Gram staining method was named after a Danish inventor Hans Christian Gram, who invented it as an approach to differentiating bacteria species in Musumeci, Trichrome Stains Historical assessment on the use of various stains in histology indicates that most pathologists were attracted by stains that gave multicolored results on the tissue specimens.

Case Study 2 The aim was to investigate the difference in capacity among different stains: Hematoxylin and Eosin, toluidine blue Stain, neuron-specific enolase NSE immunostaining and the S protein. Results and Discussion The literature review on staining techniques indicates that there has been great improvement in the histopathology and histotechnology.

Summary Histological staining is a commonly used medical process in pathological diagnosis and forensic studies. References Anderson J. An introduction to Routine and special staining. Bancroft J. D, Layton C. The Hematoxylin and eosin.

In: Suvarna S. K, Layton C, Bancroft J. D, editors. Theory Practice of histological techniques. Philadelphia: Churchill Livingstone of El Sevier; Microbiology: Principles and exploration.

John Wiley Sons; L, Prescott J. March Veterinary Pathology. X, Brito K. O, Gomes M. A, Caliari M. Histopathological and immunohistochemical study of the hepatic lesions experimentally induced by Entamoeba. Histochemical uses of haematoxylin-a review. From www. Harris T. J, McCormick F. The molecular pathology of cancer. Nat Rev Clin Oncol. Alum haematoxylin stain for the demonstration of nuclear and extra nuclear substances. Journal of Pharmacy and Clinical Sciences. In SK.

Suvarna, C. Layton JD. Bancroft Eds. Immunohistochemical techniques; pp. An ex vivo study on immunohistochemical localization of MMP-7 and MMP-9 in temporomandibular joint discs with internal derangement. Eur J Histochem. O, Horobin R. Analysis of errors in histology by root cause analysis: a pilot study.