The Importance of Tissue Orientation

By: Sheila Criswell

Recently, I selected some immunohistochemistry cases from file to photograph, and I realized that some histotechnologists do not pay much attention to orientation of tissue on the slide. Each of the 20 slides seen in Figure 1 represents a serial section in a tumor-identification case. Note how the tissues are sometimes placed at the top, middle, or bottom of slide. Note also how the tissue has no standard orientation. It is placed sometimes horizontally, vertically, or diagonally. While there is nothing inherently unacceptable in inconsistent tissue placement, there are 3 reasons to avoid this practice.

The first reason is that it might not stain appropriately if the tissue section is placed too close to the label end, or too close to the edge, particularly if automated methods are used.

The second reason is that all sections will be examined under a microscope. A pathologist does not order special stains or immunohistochemistry for no reason. He/she is trying to identify something in a particular area of the tissue. When the tissue is randomly placed on the slide, it takes more time for the pathologist to find the appropriate area. Granted the pathologist should be bright enough to win this game of hide-and-seek, but why make it more difficult? Putting the section in the same location consistently is thoughtful, akin to holding the door open for someone.

In Figure 2a, the tissue is placed more centrally on the slide and initially appears more orderly. However, there was an isolated area of tumor which is shown by the curved black lines seen in Figure 2b. Note how varied the location of the black line is. A couple of the sections represent mirror images of the original H&E, suggesting that the tissue was placed face-down on the water bath before being picked up on a slide. That practice is considered unacceptable in all labs in which I have worked, and it calls into question the skill level of the tech performing the work.

The third reason to place tissue in a similar orientation on each slide is to demonstrate a higher level of skill and a true care for the field of histotechnology. When a technologist places the tissue on the slide the same way on multiple slides, it is clear that the orientation was done on purpose. Note in Figure 3 how not only is each section positioned centrally on the slide, but is also oriented similarly. In this case, it was very easy to find the exact area of interest microscopically on each slide.

Consistent orientation of tissues is a big plus for the person doing the microscopic interpretation, and is little inconvenience for the histotechnologist who cares about the appearance of his/her work.

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