Modified staining techniques for the study of Nongeniculate coralline red algae (Rhodophyta)

Abstract

Different staining techniques of histological slides were tested and modified in order to improve and facilitate the observation of vegetative and reproductive structures that are taxonomically important for genus and species determinations of nongeniculate coralline algae (Corallinaceae, Rhodophyta). Four groups of staining techniques were differentiated from the results: a) dyes with a low affinity for the thallus: mercuric bromophenol blue, toluidine blue “O” and naphthol blue black; b) dyes with a greater affinity for the thallus: ruthenium red and red “O” oil; c) combined dyes which allowed a better staining of the thallus: naphthol blue black combined with PAS test (Periodic Acid Schiffs reagent) and toluidine blue “O” combined with sodium tetraborate; d) the dyes that gave the best staining results were: Harris’ hematoxylin, Mallory’s phosphotungstic hematoxylin, potassium permanganate (KMnO₄). PAS test and safranine-fast green.