Pathological tissue embedding technology (Part II)

In the previous article, we introduced what tissue embedding is and the selection and use of various embedding agents, and then we will take you through special embedding methods and how to achieve the best results
of paraffin embedding.
Our normal pathological specimens can obtain more satisfactory sections by paraffin embedding, but some specimens require special methods to make, and ordinary embedding methods cannot meet the requirements, such as specimens that need to be expedited, and body fluid specimens, such specimens need to have special embedding methods
.
01 The rapid paraffin embedding method is mainly used for the rapid diagnosis of expedited specimens, and the tissue block is too small or too broken to be prepared by freezing sectioning, and the material should be thin
.
The thin tissue block was put into a mixed fixation and dehydration solution of 40% formaldehyde 10ml, 95% ethanol 85ml, glacial cu acid 5ml for 2 minutes, pure acetone I for 3 minutes, pure acetone II for 3 minutes, benzene for 2 minutes, immersion wax for 5 minutes, and the tissue was quickly embedded for cooling sectioning, baking tablets, dewaxing to water, dyeing and sealing
.
02 Paraffin embedding method can also be used
for biopsy of body fluid specimens, such as sputum, gastric juice, urine, ascites and pleural fluid.
If it is sputum, the part containing blood or the suspicious solid part of the sputum should be selected, wrapped in a double layer of gauze, first fixed with 10% neutral formaldehyde, then dehydrated, transparent and impregnated with wax, and finally embedded
.
The turbid liquid was put into a centrifuge tube and precipitated by centrifugation at a speed of 2000~3000 times/min for 15 seconds
.
All liquid specimens such as fresh gastric juice, urine, ascites and pleural fluid should first pour the clear liquid above, put the more turbid liquid below into the centrifuge tube, and centrifuge and precipitate at a speed of 2000~3000 times/min for 5~10 minutes
.
The supernatant is then poured out and the underlying pellet is fixed with 10% formaldehyde, then dehydrated, clear, waxed impregnated, and embedding
.
How to make paraffin embedding achieve the best effect We can do some work to improve the effect of paraffin embedding and improve the toughness and viscosity of paraffin wax with human force: this method is to add some other substances
to paraffin.
01 Beeswax beeswax, also known as yellow wax, is a light yellow wax used by bees to make nests, the melting point of beeswax is about 54 °C, soft texture, smooth and tough
.
In order to make the paraffin with low melting point harder, 10%~20% beeswax
can be added.
It increases the melting point of the wax without immersing the tissue in high temperatures, facilitating sectioning
.
At the same time, it should also vary according to the type of tissue, and the general conventional dosage does not exceed 5%.

Generally, if we cut 4~5μm slices, 56~58 °C paraffin wax basically meets the standard, but if you want to cut 1~3μm sections, its toughness and viscosity are not enough, there will be paraffin wax can not support the phenomenon, because the light hardness paraffin wax will be very brittle, easy to break, if beeswax is added, so that its toughness and viscosity are strengthened, you can make better slices
.
02 Stearic acid If you want to strengthen the hardness of paraffin, you can add stearic acid, rosin, etc
.
Stearic acid is a glossy white flake crystal, insoluble in water, but soluble in ethanol, ether and chlorofang
.
Melting point 64~71 °C, adding a small amount of stearic acid to the wax can increase the permeability of paraffin.

03 Rosin is a brown-yellow translucent solid, hard and brittle, melted by heat, colloidal, mixed with paraffin, can increase the hardness of paraffin, because rosin is brittle, after mixing can increase the hardness but the toughness is insufficient
.
Of course, the use of good quality paraffin is also important, can not save money, and buy paraffin wax with a lot of impurities, the cut out piece is not much better
.
Because it contains too many impurities, it not only affects the soaking of paraffin wax to the tissue, but also scratches the sheet due to excessive impurities and large particles when
sectioning 。 Leica offers a variety of paraffin waxes to choose from, including 39601006 (Paraplast Regular paraffin, commonly used, granulated, 8*1kg/carton, 56°C, dehydrated/embedding general) and 39601095 (Paraplast High Melt paraffin, high melting point type, granule, 8 kg, 56-58°C, dehydrated/embedding general) Guangzhou Dongrui standing stock
.
If you need to purchase products, you can contact Guangzhou Dongrui Technology Co.
, Ltd.