Percentage of formalin used for histopathological preservative?: (A) 5%, (B) 10%, (C) 20%, (D) 40%
Answer is B. 2Ans. (b) 10%Ref: Handbook of Histopathological and Histochemical Techniques 3rd ed. / 40-45* Formalin is generally the preferred fluid for fixation and is widely used. Formalin is often sold as 37-40% aqueous Formaldehyde.* To make a solution of 10% Formalin, nine parts of water are added to one part of 40% (aqueous) Formaldehyde.* Therefore, a 10% solution of Formalin is the equivalent of a 4% solution of Formaldehyde.* Formaldehyde is a gas produced by the oxidation of methyl alcohol, whereas 100% Formalin is a saturated solution of this gas in water.Other Histopathological Preservatives:* Glutaraldehyde: 25%-for electron microscopy (with osmium tetra-chloride)* Acetaldehyde acrolein* Mercuric chloride* Potassium dichromate