<prompt> Which of the following is homogenously pink staining extracellular fibrillar protein on congo red staining?ElastinAmyloidCollagenActin  <response>: Ans. is b i.e., Amyloid Congo red is most specific and most commonly used stain stain used for amyloidosis. Appearance of amyloid fibrillary extracellular protein are:-a Congo red stain on light microscopy: Pink or red color to tissue deposits.b Congo red stain on polarized microscopy: Apple green birefringence. 