The page below is a sample from the LabCE course Histology Special Stains: Carbohydrates. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about Histology Special Stains: Carbohydrates (online CE course) »
How to Subscribe
Histology CE Package$65 Add to cart
Individual course$20 Add to cart

PAS fungal stain; fast green counterstain

Periodic Acid-Schiff (PAS): Counterstaining with Fast Green

Fast green should be used as a counterstain when using PAS staining procedures to demonstrate the presence of fungal organisms in tissue sections. 

For a fast green counterstain, continue any of the PAS staining protocols with the following step:
  • Fast green (0.02% solution) for 30 seconds

Expected result: The PAS-negative background elements will stain green.

Post staining procedure:
  • After counterstain, tissue sections should be rinsed quickly in distilled water, as fast green is easily rinsed out of tissue sections.
  • Following the quick water rinse, sections should be dehydrated with 95% alcohol, followed by 100% alcohols, cleared with xylene (or xylene substitute), and cover-slipped.