This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
The ocular basement membrane is stained with 
Select and explain. 
A. Alcaine blue, B. Giemsa stain, C. Methylene blue, D. Periodic acid-Schiff
D: Periodic acid-Schiff
Answer: D: Periodic acid-Schiff 
Explanation: Not only ocular almost all basement membranes are stained with PAS (Periodic acid-Schiff) Because they have mucopolysaccharides.Periodic acid-Schiff reactive (PAS) method is principally used to demonstrate structures rich in polysaccharides (glycogen), mucopolysaccharides (e.g., ground substance of connective tissues, basement membrane, and mucus), glycoproteins (thyroglobulin), and glycolipids.