1. A grainlike particle; a granulation; a minute discrete mass. 2. A very small pill, usually gelatin or sugar coated, containing a drug to be given in a small dose. 3. A colony of the bacterium or fungus causing a disease or simply colonizing the tissues of the patient. In immunocompromised patients the differentiation is difficult. 4. A small particle that can be seen by electron microscopy; contains stored material. [L. granulum, dim. of granum, grain]
- α granules large, rodlike, or filamentous granules found in several types of cells, especially platelets where they are the most numerous type of g.; contain secretory proteins, including fibrinogen, fibronectin, fibrospondin, von Willebrand factor (collectively known as adhesive proteins) and other proteins (platelet factor 4, platelet-derived growth factor, coagulation factor V, etc.).
- acrosomal g. the single glycoprotein rich g. within an acrosomal vesicle, which results from the coalescence of proacrosomal granules.
- alpha g. a g. of an alpha cell that was named as the first of several kinds or because it was acidophilic.
- argentaffin granules granules that reduce silver ions from an ammoniac silver nitrate staining solution.
- azurophil g. a g. that stains a reddish purple color with an azure dye; such granules are seen in dry smears of certain mature and developing blood cells, and are membrane-bound primary lysosomes containing enzymes. SYN: kappa g..
- basophil g. a g. that stains readily with a basic dye.
- Birbeck g. SYN: Langerhans g..
- Bollinger granules 1. relatively small, but frequently microscopically visible, pale yellow or yellow-white granules observed in the granulomatous lesion, or the exudate, in botryomycosis; the granules consist of irregular aggregates or colonizations of Gram-positive cocci, usually staphylococci; 2. term sometimes incorrectly used synonymously with Bollinger bodies.
- chromatic g. SYN: chromophil g. (2).
- chromophil g. 1. any readily stainable g.; 2. a g. of chromophil (Nissl) substance. SYN: chromatic g..
- chromophobe granules granules that do not stain or stain poorly with the ordinary dyes; such granules are present in some cells in the anterior lobe of the pituitary.
- Crooke granules lumpy masses of basophilic material in the basophil cells of the anterior lobe of the pituitary, associated with Cushing disease, or following the administration of ACTH.
- eosinophil g. a g. that stains with eosin.
- glycogen g. glycogen occurring in cells as beta granules which average about 300 Å in diameter, or as alpha granules which are aggregates measuring 900 Å of smaller particles.
- iodophil g. a g. that stains brown with iodine; found in many of the polymorphonuclear leukocytes in pneumonia, erysipelas, scarlet fever, and various other acute diseases.
- juxtaglomerular granules osmophilic secretory granules present in the juxtaglomerular cells, thought to contain renin.
- kappa g. SYN: azurophil g..
- keratohyalin granules irregularly shaped basophilic granules in the cells of the stratum granulosum of the epidermis.
- lamellar g. SYN: keratinosome.
- Langerhans g. a small tennis racket-shaped membrane-bound g. with characteristic cross-striated internal ultrastructure; first reported in Langerhans cells of the epidermis. SYN: Birbeck g..
- membrane-coating g. SYN: keratinosome.
- metachromatic granules 1. granules that stain a color different from that of the dye used; SEE ALSO: metachromasia. 2. term sometimes used as a synonym for volutin.
- mucinogen granules granules that produce mucin, as in cells of the salivary glands and in the gastric and intestinal mucosae.
- Neusser granules tiny basophilic granules sometimes observed in an indistinct zone about the nucleus of a leukocyte.
- neutrophil g. a g. stainable with the neutral component of stains, e.g., the Romanovsky-type blood stains.
- oxyphil g. SYN: acidophil g..
- proacrosomal granules small carbohydrate-rich granules appearing in vesicles of the Golgi apparatus of spermatids; they coalesce into a single acrosomal g. contained within an acrosomal vesicle.
- prosecretion granules granules in the cytoplasm of a cell indicative of a preliminary step in the formation of a secretory product.
- Schüffner granules SYN: Schüffner dots, under dot.
- secretory g. a membrane-bound particle, usually protein, formed in the granular endoplasmic reticulum and the Golgi complex.
- specific granules the distinctive granules of basophilic, eosinophilic, and neutrophilic leukocytes, as opposed to their nonspecific azurophilic granules.
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gran·ule 'gran-(.)yü(ə)l n
1 a) a little grain or small particle esp one of a number of particles forming a larger unit
b) a small sugar-coated pill
2) a clump of actinomycetes in a lesion
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gran·ule (granґūl) [L. granulum] 1. a small particle or grain, as the small beadlike masses of tissue formed on the surface of wounds, or the insoluble nonmembranous particles found in cytoplasm. 2. a small pill made from sucrose.Medical dictionary. 2011.