Introduction to Pathology vol.2


Hello! I’m Naoko from recruitment / public relations team at Medmain.

In this blog “Medmain Speaks”, you will find interviews with members at Medmain, as well as a series of articles on pathology.

I would be happy if this post would be an opportunity for more of you to deepen understanding of the importance of “pathology,” which plays an important role in the area of medicine.

Today, I would like to introduce how the prepared glass used in pathological diagnosis is made.

Pathologists use a microscope to observe cells and other objects taken from the body, but for the microscope, “transmitted light” is used. That means they can only see translucent objects because the specimen

is lit up from bottom of the microscope but they look into the microscope from the top. If the specimen is too thick, the light is blocked and it becomes like a shadow picture, and the cells or tissues cannot be seen at all.

For this reason, it is required to make the harvested organ “translucent” before observing them.

How do they make it translucent…? The answer is, that they make a thin layer like a film of the area they want to observe.

In order to make this extremely thin layer from the surface of organ, a thin slicing device called “Microtome” like the one shown below is used. The layer is very thin, with a thickness of 3 μm to 5 μm.

However, this is meaningless unless the extremely thin film contains the part that they actually want to observe.

When they take a lump of an organ and want to observe something inside ,it takes them forever until they get to the spot by grinding the canner 3 μm at a time.

Therefore, an important process is called “Grossing” also known as “cut up”, which should be done before the thin-cutting process.

Before using the thin-slice device, they cut an organ about 5 mm from a specimen (called a macro specimen) that has been hardened by formalin, as shown in the photo below.

They observe the lesion with the naked eye first and decide which part should be observed with microscope, the next step is to “cut out” the necessary lesions.

Of course, they carry out this process with careful observation, lots of photography and recording of the location of the lesion.

This is an extremely important process in histopathology which is done in collaboration with the pathologist and laboratory technologist.

This “cut up” process requires a lot of skill.

After this process, the cut out lesion is hardened with paraffin wax, then becomes a thin layer, and is attached to the glass slide with a heat of about 50 degrees Celsius.

The final process is “Staining”. They are usually dyed pink or purple by an automatic dyeing device or by hand using a method called “hematoxylin and eosin staining (HE staining) “ to make it easier to judge when observed under a microscope.

Then, the glass specimen will be passed to the pathologist.

pathologist’s view of the world under the microscope is like this below

Specimen Preparation steps

Treatment/Surgery>>Fixation>>Grossing>>Processing/Sectioning>>Staining