Acetic orcein staining of prefixed tissue sections

Area of Science:

• Histology
• Cytology
• Staining Techniques

Background:

• Histological stains are crucial for visualizing cellular and tissue structures.
• Acetic orcein is a known stain with specific affinities for certain cellular components.

Purpose of the Study:

• To evaluate the staining properties of acetic orcein on different tissue types and cellular components.
• To assess the compatibility of acetic orcein with other common histological stains and fixatives.

Main Methods:

• Formol- and Carnoy-fixed tissues were stained with acetic orcein.
• Staining intensity was assessed for various components like mast cells, nuclei, cartilage, keratin, erythrocytes, muscle, and collagen.
• Compatibility with fast-green FCF, Prussian blue, and Turnbull's blue reactions was evaluated.
• Mucin staining in Brunner gland and goblet cells was specifically tested.

Main Results:

• Acetic orcein strongly stains mast cells, nuclei, basophilic cytoplasm, cerebral corpora amylacea, and cartilage.
• Keratin and erythrocytes show moderate staining, while muscle and collagen stain weakly.
• Mucins in guinea pig Brunner gland and rat colonic goblet cells were not stained.
• The red nuclear stain provides good contrast with Prussian blue (hemosiderin) and Turnbull's blue (enterochromaffin).
• A 0.01% fast-green FCF counterstain enhances collagen and smooth muscle visualization without affecting nuclear or mast cell staining.
• Picroindigocarmine stains collagen blue, muscle yellow, and elastin/nucleic acids/mast cells red.
• Picro-methyl blue can obscure the red nuclear stain.

Conclusions:

• Acetic orcein is a valuable stain for nuclei, mast cells, and cartilage, offering good contrast with iron and enterochromaffin stains.
• It is not suitable for mucin visualization.
• Combinations with fast-green FCF, picroindigocarmine, and careful use of picro-methyl blue allow for multi-component tissue analysis.