POCD Scientific specialises in the manufacture of state-of-the-art preformulated stains, made with certified powders, reliable liquid solutions & fixatives.
We offer a comprehensive range of formulations as well as our custom manufacturing service for your individual requirements - we are committed to providing custom formulations for the same price as preformulated products. Please contact POCDS on 1800 640 075 (free call) to discuss how we can help you make a difference in your laboratory.
All our stains are precisely formulated with rigorous quality assurance testing, performing optimally and predictability with both manual and automated staining procedures.
Pap staining is used to differentiate cells in smear preparations of various bodily secretions; the specimens can be gynecological smears (Pap smears), sputum, brushings, washings, urine, cerebrospinal fluid, abdominal fluid, pleural fluid, synovial fluid, seminal fluid, fine needle aspiration material, tumor touch samples, or other materials containing cells.
Pap staining is a very reliable technique. As such, it is used for cervical cancer screening in gynecology. The entire procedure is known as Pap smear.
The classic form of Pap stain involves five dyes in three solutions:
A nuclear stain, haematoxylin, is used to stain cell nuclei. The unmordanted haematein may be responsible for the yellow color imparted to glycogen.
First OG-6 counterstain (-6 denotes the used concentration of phosphotungstic acid; other variants are OG-5 and OG-8). Orange G is used. It stains keratin. Its original role was to stain the small cells of keratinizing squamous cell carcinoma present in sputum.
Second EA (Eosin Azure) counterstain, comprising three dyes; the number denotes the proportion of the dyes, eg. EA-36, EA-50, EA-65.
Eosin Y stains the superficial epithelial squamous cells, nucleoli, cilia, and red blood cells.
Light Green SF yellowish stains the cytoplasm of all other cells. This dye is now quite expensive and difficult to obtain, therefore some manufacturers are switching to Fast Green FCF, however it produces visually different results and is not considered satisfactory by some.
Bismarck brown Y stains nothing and in contemporary formulations it is often omitted.
When performed properly, the stained specimen should display hues from the entire spectrum: red, orange, yellow, green, blue, and violet. The chromatin patterns are well visible, the cells from borderline lesions are easier to interpret and the photomicrographs are better. The staining results in very transparent cells, so even thicker specimens with overlapping cells can be interpreted.
On a well prepared specimen, the cell nuclei are crisp blue to black. Cells with high content of keratin are yellow, glycogen stains yellow as well. Superficial cells are orange to pink, and intermediate and parabasal cells are turquoise green to blue. Metaplastic cells often stain both green and pink at once.
Pap stain is not fully standardized; it comes in several versions, subtly differing in the exact dyes used, their ratios, and timing of the process.
The EA stain contains two mutually incompatible chemicals, Bismarck brown and phosphotungstic acid, which precipitate each other, impairing the useful life of the mixture and compromising the differential staining of eosin and light green. The descriptions of the compositions of the staining solutions vary by source and differ even in Papanicolaou's own publications. Mixtures of the same name from different vendors therefore can differ in composition, occasionally producing different or poor results.
Cytology Supplies ~ Fixation
Cyto Wax Spray Fixative – a spray fixative containing carbowax
Carnoys Fixative - a coagulative fixative which changes the shape or structure of protein molecules without binding to them.
Cytology Supplies ~ Mountants
Slidemount # 1 through 9 : Refractive index 1.515. This is acrylate/methacrylate based with Xylene as the solvent. Fast drying [touch dry in 3-4mins] and permanent [coverslips are difficult to remove]. The numbers relate to viscosity. No 1 is very thick and No 9 thin. Please note the most common viscosity is No 4, which is equivalent to Eukitt. However Ultramount No 9 has now been released, which is especially formulated for automatic cover-slipping machines.
Aquamount – This is a water based mountant and is used for special staining techniques where the use of solvents removes the component being stained. This is not a permanent mountant. Otherwise known as Apathy's mountant.
Citramount – No 4 and 7 : Is again Perspex based but with Citrolene as the solvent. If one is clearing with Histolene [our Xylene replacement solvent] then this mountant is better suited. Also available in our popular Safe-T-Mount squeeze tubes.