Eosin

For the eosin glazing process, see Zsolnay.Eosin is a fluorescent acidic / negative compound that

COO-

O

Br

O- O

Br Br

Br

Eosin Y

Eosin B

binds to and forms salts with basic, or eosinophilic, com-pounds containing positive charges (such as proteins thatare basic / positive due to the presence of amino acidresidues such as Arginine and Lysine) and stains themdark red or pink as a result of the actions of bromineon fluorescein. In addition to staining proteins in thecytoplasm, it can be used to stain collagen and musclefibers for examination under the microscope. Structuresthat stain readily with eosin are termed eosinophilic.

1 Etymology

The name Eosin comes from Eos, the Ancient Greekword for 'dawn' and the name of the Ancient Greek god-dess of the dawn.

2 Variants

There are actually two very closely related compoundscommonly referred to as eosin. Most often used is EosinY (also known as eosin Y ws, eosin yellowish,Acid Red87, C.I. 45380, bromoeosine, bromofluoresceic acid,D&C Red No. 22); it has a very slightly yellowish cast.The other eosin compound is eosin B (eosin bluish,AcidRed 91, C.I. 45400, Saffrosine, Eosin Scarlet, or im-perial red); it has a very faint bluish cast. The two dyesare interchangeable, and the use of one or the other is amatter of preference and tradition.Eosin Y is a tetrabromo derivative of fluorescein.[1] EosinB is a dibromo dinitro derivative of fluorescein.[2]

3 Use in histology

Sample of a trachea coloured with hematoxylin and eosin.

Eosin is most often used as a counterstain to hematoxylinin H&E (haematoxylin and eosin) staining. H&E stain-ing is one of the most commonly used techniques inhistology. Tissue stained with haematoxylin and eosinshows cytoplasm stained pink-orange and nuclei staineddarkly, either blue or purple. Eosin also stains red bloodcells intensely red.

1

2 6 EXTERNAL LINKS

For staining, eosin Y is typically used in concentrationsof 1 to 5 percent weight by volume, dissolved in wateror ethanol.[3] For prevention of mold growth in aqueoussolutions, thymol is sometimes added.[4] A small concen-tration (0.5 percent) of acetic acid usually gives a deeperred stain to the tissue.It is listed as an IARC class 3 carcinogen.

4 See also• Haematoxylin

• H&E stain

• Romanowsky stain

• Merbromin

5 References• Jocelyn H. Bruce-Gregorios, M.D.: HistopathologicTechniques, JMC Press Inc., Quezon City, Philip-pines, 1974.

[1] Its CAS number is 17372-87-1 and its SMILESstructure is O=C5C(Br)=C2O C1=C(Br)C([O-]) =C(Br)C=C1C(C4=C (C([O-])=O)C=CC=C4)=C2C=C3Br.

[2] Its CAS number is 548-28-3 and its SMILES structureis O=C5C(Br)=C2O C1=C(Br)C([O-]) =C([N+]([O-])=O) C=C1C(C4=C(C([O-]) =O)C=CC=C4)=C2C=C3[N+]([O-])=O.

[3] http://protocolsonline.com/histology/dyes-and-stains/haematoxylin-eosin-he-staining/

[4] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC291425/pdf/aem00234-0146.pdf

6 External links• Eosin Y - Applications information

3

7 Text and image sources, contributors, and licenses

7.1 Text• Eosin Source: http://en.wikipedia.org/wiki/Eosin?oldid=634560947 Contributors: Mav, Stan Shebs, Hankwang, Gak, Huddy, Nunh-huh,Arcadian, RJFJR, TenOfAllTrades, Swamp Ig, Ekem, Eleassar777, FlaBot, Eubot, Borgx, Shaddack, DavidConrad, Thallinger, Retiredusername, Chefyingi, GrinBot, SmackBot, Moez, InvictaHOG, EncycloPetey, Radagast83, FrozenMan, Beetstra, Mousda, Dlohcierekim,Alexei Kouprianov, Chrumps, Thijs!bot, Albmont, Adacus12, ChemNerd, AlphaEta, Lchrzan, Lamialestat, DorganBot, VolkovBot, TXiK-iBoT, Lejarrag, The Devil’s Advocate, SieBot, Thelmadatter, Chem-awb, Jekatz, Addbot, Miczilla, Luckas-bot, Yobot, Amirobot, Ober-sachsebot, البط علي ,حسن GrouchoBot, RibotBOT, D'ohBot, LittleWink, Yanglifu90, Netha Hussain, Whoop whoop pull up, ChesterMarkel, TruPepitoM, Gauravjuvekar, Cdepgh and Anonymous: 30

7.2 Images• File:Eosin_B.png Source: http://upload.wikimedia.org/wikipedia/commons/e/e9/Eosin_B.png License: Public domain Contributors: ?Original artist: ?

• File:Eosin_Y.svg Source: http://upload.wikimedia.org/wikipedia/commons/9/95/Eosin_Y.svg License: Public domain Contributors:Roland1952 Original artist: Roland Mattern

• File:Histological_sample_of_Trachea_obtained_at_\char"0022\relax{}Instituto_Nacional_de_Cardiología_Ignacio_A._Chávez”.JPG Source: http://upload.wikimedia.org/wikipedia/commons/c/ce/Histological_sample_of_Trachea_obtained_at_%22Instituto_Nacional_de_Cardiolog%C3%ADa_Ignacio_A._Ch%C3%A1vez%22.JPG License: CC-BY-SA-3.0 Contributors: Ownwork Original artist: Dr.TorresValencia

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