Adaptation of the Mallory-Azan Staining Method to the Anterior Pituitary of the Rat

A staining procedure by modification of the “Mallory-azan” method, as adapted to the anterior pituitary of the rat, is described. No claim is made that the fundamental principle of the procedure is new; but because it invariably differentiates sharply the three classical cell types it is felt that the technic should be published. Pituitaries are fixed in Zenker-formol solution, embedded in nitrocellulose and cut at 3-4 μ. Sections are affixed to the slides, prior to the staining procedure, with the aid of albumin-glycerin, and nitrocellulose is removed with oil of cloves. After the sections are properly stained with azocarmine and treated with 5% phosphotungstic acid, as a separate step, they are stained with Mallory's anilinblue-orange-G mixture.1 It was, however, found advantageous not to omit oxalic acid and to decrease considerably the amount of phosphotungstic acid given in the formula. After the staining in this solution is completed, sections are again treated with 5% phosphotungstic acid, followed by acidulated and distilled water (to eliminate the excess of anilin blue in the cytoplasm). Finally sections are dehydrated in absolute alcohol and mounted in euparal.