![<span class="mw-page-title-main">Histology</span> Study of the microscopic anatomy of cells and tissues of plants and animals](https://upload.wikimedia.org/wikipedia/commons/thumb/9/95/Slide_under_a_microscope.jpg/320px-Slide_under_a_microscope.jpg)
Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures visible without a microscope. Although one may divide microscopic anatomy into organology, the study of organs, histology, the study of tissues, and cytology, the study of cells, modern usage places all of these topics under the field of histology. In medicine, histopathology is the branch of histology that includes the microscopic identification and study of diseased tissue. In the field of paleontology, the term paleohistology refers to the histology of fossil organisms.
![<span class="mw-page-title-main">Haematoxylin</span> Natural stain derived from hearthwood and used in histology](https://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Haematoxylin_powder.jpg/320px-Haematoxylin_powder.jpg)
Haematoxylin or hematoxylin, also called natural black 1 or C.I. 75290, is a compound extracted from heartwood of the logwood tree with a chemical formula of C
16H
14O
6. This naturally derived dye has been used as a histologic stain, as an ink and as a dye in the textile and leather industry. As a dye, haematoxylin has been called palo de Campeche, logwood extract, bluewood and blackwood. In histology, haematoxylin staining is commonly followed by counterstaining with eosin. When paired, this staining procedure is known as H&E staining and is one of the most commonly used combinations in histology. In addition to its use in the H&E stain, haematoxylin is also a component of the Papanicolaou stain which is widely used in the study of cytology specimens.
![<span class="mw-page-title-main">Eosin</span> Group of bromo derivatives of fluorescein used as red dye](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b0/Eosin_Y_Structural_Formulae_V.1.svg/320px-Eosin_Y_Structural_Formulae_V.1.svg.png)
Eosin is the name of several fluorescent acidic compounds which bind to and form salts with basic, or eosinophilic, compounds like proteins containing amino acid residues such as arginine and lysine, and stains them dark red or pink as a result of the actions of bromine on eosin. In addition to staining proteins in the cytoplasm, it can be used to stain collagen and muscle fibers for examination under the microscope. Structures that stain readily with eosin are termed eosinophilic. In the field of histology, Eosin Y is the form of eosin used most often as a histologic stain.
![<span class="mw-page-title-main">Mordant</span> Substance used for binding dyes to fabrics](https://upload.wikimedia.org/wikipedia/commons/thumb/5/54/Mordant_red_19.png/320px-Mordant_red_19.png)
A mordant or dye fixative is a substance used to set dyes on fabrics. It does this by forming a coordination complex with the dye, which then attaches to the fabric. It may be used for dyeing fabrics or for intensifying stains in cell or tissue preparations. Although mordants are still used, especially by small batch dyers, they have been largely displaced in industry by directs.
![<span class="mw-page-title-main">Staining</span> Technique used to enhance visual contrast of specimens observed under a microscope](https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Stained_microscope_slide.jpg/320px-Stained_microscope_slide.jpg)
Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology, in cytology, and in the medical fields of histopathology, hematology, and cytopathology that focus on the study and diagnoses of diseases at the microscopic level. Stains may be used to define biological tissues, cell populations, or organelles within individual cells.
![<span class="mw-page-title-main">Eosinophilic</span> Quality of being colored by eosin](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Eosinophilic%2C_basophilic%2C_chromophobic_and_amphophilic_staining.png/320px-Eosinophilic%2C_basophilic%2C_chromophobic_and_amphophilic_staining.png)
Eosinophilic is the staining of tissues, cells, or organelles after they have been washed with eosin, a dye.
![<span class="mw-page-title-main">Basophilic</span> Microscopic appearance of cells stained with a basic dye](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Eosinophilic%2C_basophilic%2C_chromophobic_and_amphophilic_staining.png/320px-Eosinophilic%2C_basophilic%2C_chromophobic_and_amphophilic_staining.png)
Basophilic is a technical term used by pathologists. It describes the appearance of cells, tissues and cellular structures as seen through the microscope after a histological section has been stained with a basic dye. The most common such dye is haematoxylin.
![<span class="mw-page-title-main">Eosin Y</span> Chemical compound](https://upload.wikimedia.org/wikipedia/commons/thumb/9/95/Eosin_Y.svg/320px-Eosin_Y.svg.png)
Eosin Y, also called C.I. 45380 or C.I. Acid Red 87, is a member of the triarylmethane dyes. It is produced from fluorescein by bromination.
![<span class="mw-page-title-main">Hematein</span> Chemical compound](https://upload.wikimedia.org/wikipedia/commons/thumb/f/f6/Haematein.png/320px-Haematein.png)
Hematein or haematein is an oxidized derivative of haematoxylin, used in staining. Haematein should not be confused with haematin, which is a brown to black iron-containing pigment formed by decomposition of haemoglobin. In the Colour Index, haematein is called haematine.
![<span class="mw-page-title-main">Masson's trichrome stain</span> Biological staining procedure used in study of tissues](https://upload.wikimedia.org/wikipedia/commons/thumb/2/29/Masson%27s_Trichrome_Stain_%28Rat_Airway_Section%29.jpg/320px-Masson%27s_Trichrome_Stain_%28Rat_Airway_Section%29.jpg)
Masson's trichrome is a three-colour staining procedure used in histology. The recipes emerged from Claude L. Pierre Masson's (1880–1959) original formulation have different specific applications, but all are suited for distinguishing cells from surrounding connective tissue.
![<span class="mw-page-title-main">Papanicolaou stain</span> Histological staining method](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Low_grade_squamous_intraepithelial_lesion.jpg/320px-Low_grade_squamous_intraepithelial_lesion.jpg)
Papanicolaou stain is a multichromatic (multicolored) cytological staining technique developed by George Papanicolaou in 1942. The Papanicolaou stain is one of the most widely used stains in cytology, where it is used to aid pathologists in making a diagnosis. Although most notable for its use in the detection of cervical cancer in the Pap test or Pap smear, it is also used to stain non-gynecological specimen preparations from a variety of bodily secretions and from small needle biopsies of organs and tissues. Papanicolaou published three formulations of this stain in 1942, 1954, and 1960.
![<span class="mw-page-title-main">Phosphotungstic acid-haematoxylin stain</span> Biological stain used for staining of tissues](https://upload.wikimedia.org/wikipedia/commons/thumb/0/06/Acute_myocardial_infarction_with_contraction_band_necrosis_%281%29_PTAH.JPG/320px-Acute_myocardial_infarction_with_contraction_band_necrosis_%281%29_PTAH.JPG)
Phosphotungstic acid haematoxylin (PTAH) is a mix of haematoxylin with phosphotungstic acid, used in histology for staining.
![<span class="mw-page-title-main">Phosphotungstic acid</span> Chemical compound](https://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Phosphotungstate-3D-polyhedra.png/320px-Phosphotungstate-3D-polyhedra.png)
Phosphotungstic acid (PTA) or tungstophosphoric acid (TPA), is a heteropoly acid with the chemical formula H3PW12O40]. It forms hydrates H3[PW12O40]·nH2O. It is normally isolated as the n = 24 hydrate but can be desiccated to the hexahydrate (n = 6). EPTA is the name of ethanolic phosphotungstic acid, its alcohol solution used in biology. It has the appearance of small, colorless-grayish or slightly yellow-green crystals, with melting point 89 °C (24 H2O hydrate). It is odorless and soluble in water (200 g/100 ml). It is not especially toxic, but is a mild acidic irritant. The compound is known by a variety of names and acronyms (see 'other names' section of infobox).
![<span class="mw-page-title-main">Acidophile (histology)</span>](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Eosinophilic%2C_basophilic%2C_chromophobic_and_amphophilic_staining.png/320px-Eosinophilic%2C_basophilic%2C_chromophobic_and_amphophilic_staining.png)
Acidophile is a term used by histologists to describe a particular staining pattern of cells and tissues when using haematoxylin and eosin stains. Specifically, the name refers to structures which "love" acid, and take it up readily. More specifically, acidophilia can be described by cationic groups of most often proteins in the cell readily reacting with acidic stains.
![<span class="mw-page-title-main">Brazilin</span> Chemical compound](https://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Brazilin.svg/320px-Brazilin.svg.png)
Brazilin is a naturally occurring, a homoisoflavonoid, red dye obtained from the wood of Paubrasilia echinata, Biancaea sappan, Caesalpinia violacea, and Haematoxylum brasiletto. Brazilin has been used since at least the Middle Ages to dye fabric, and has been used to make paints and inks as well. The specific color produced by the pigment depends on its manner of preparation: in an acidic solution brazilin will appear yellow, but in an alkaline preparation it will appear red. Brazilin is closely related to the blue-black dye precursor hematoxylin, having one fewer hydroxyl group. Brazilein, the active dye agent, is an oxidized form of brazilin.
Infantile digital fibromatosis (IDF), also termed inclusion body fibromatosis, Reye tumor, or Reye's tumor, usually occurs as a single, small, asymptomatic, nodule in the dermis on a finger or toe of infants and young children. IMF is a rare disorder with approximately 200 cases reported in the medical literature as of 2021. The World Health Organization in 2020 classified these nodules as a specific benign tumor type in the category of fibroblastic and myofibroblastic tumors. IDF was first described by the Australian pathologist, Douglas Reye, in 1965.
![<span class="mw-page-title-main">Perls Prussian blue</span> Histologic method to stain for iron](https://upload.wikimedia.org/wikipedia/commons/thumb/8/82/Siderophage_iron_stain_CSF.jpg/320px-Siderophage_iron_stain_CSF.jpg)
In histology, histopathology, and clinical pathology, Perls Prussian blue is a commonly used method to detect the presence of iron in tissue or cell samples. Perls Prussian Blue derives its name from the German pathologist Max Perls (1843–1881), who described the technique in 1867. The method does not involve the application of a dye, but rather causes the pigment Prussian blue to form directly within the tissue. The method stains mostly iron in the ferric state which includes ferritin and hemosiderin, rather than iron in the ferrous state.
![<span class="mw-page-title-main">Luxol fast blue stain</span>](https://upload.wikimedia.org/wikipedia/commons/thumb/1/17/Pons_-_very_high_mag.jpg/320px-Pons_-_very_high_mag.jpg)
Luxol fast blue stain, abbreviated LFB stain or simply LFB, is a commonly used stain to observe myelin under light microscopy, created by Heinrich Klüver and Elizabeth Barrera in 1953. LFB is commonly used to detect demyelination in the central nervous system (CNS), but cannot discern myelination in the peripheral nervous system.
Verhoeff's stain, also known as Verhoeff's elastic stain (VEG) or Verhoeff–Van Gieson stain (VVG), is a staining protocol used in histology, developed by American ophthalmic surgeon and pathologist Frederick Herman Verhoeff (1874–1968) in 1908. The formulation is used to demonstrate normal or pathologic elastic fibers.
![<span class="mw-page-title-main">Dmitri Leonidovich Romanowsky</span> Russian physician](https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Romanovsky.jpg/320px-Romanovsky.jpg)
Dmitri Leonidovich Romanowsky was a Russian physician who is best known for his invention of an eponymous histological stain called Romanowsky stain. It paved the way for the discovery and diagnosis of microscopic pathogens, such as malarial parasites, and later developments of new histological stains that became fundamental to microbiology and physiology.