Paraldehyde fuchsin (aldehyde fuchsin stock solution) is a special staining solution in concentrated form used in histology and cytology. This stock solution is used to prepare the actual working solution, which is used for staining and identification of elastic fibers, basement membranes, mast cells and nerve cells.

The stock solution consists of aqua dist./VE water, basic fuchsin, hydrochloric acid, paraldehyde and ethanol. Basic fuchsin is the primary dye that, in combination with hydrochloric acid, promotes its binding to target structures in tissue. Paraldehyde reacts with basic fuchsin to form aldehyde fuchsin, which binds specifically to certain tissue structures. Ethanol and aqua dist./VE water serve as solvents and assist the penetration of the dye into the tissue.

Overall, the paraldehyde fuchsin stock solution enables effective and reliable staining in histological and cytological specimens after transfer to the appropriate working solution.