The pathology attending usually gives instructions to the technician regarding embedding. We do that with written instructions and on the laboratory computer. .
As you know, all specimens must be accompanied by a routing slip which indicates where the specimen should be sent (cytology, immunohistochemistry, etc.). Instructions for embedment must be written on the routing slip or if no directions for embedment are given to the technologist, the tissue will be embedded on the flat surface rather than any edge. Thus, if any other method of embedment for sectioning is desired (on edge, on end, etc.), the edge or end must be marked with an orange dye (mercurochrome works well) which will remain after dehydration and paraffin infiltration to guide the technologist during embedment (see next page). An example of this would be the cornea, which must be sectioned perpendicular to the surface in order to study all layers at a given level and in a given section. Complicated specimens require diagrams and verbal communication with the technologist. Very complicated specimens should be embedded by with the aid of the technologist. Do not underestimate the importance of proper orientation of the specimen.
KEY ELEMENTS OF PROPER EMBEDDING (click on Figure 1 to ENLARGE in a new window!)
1. As stated above, the surface to be cut can be marked with mercurochrome.
2. Skin or mucosa also may be oriented by putting India ink on the epithelial surface and let the technologist know (by written instructions or tag) that the specimen is "skin". The specimen will then be cut perpendicular to the mark.
3. A flat piece of tissue may also be cut on the edge by instructing "cut on edge" (either orally or by instructions on the routing slip).
4. Surgical margins of all specimens with, or suspected of having neoplasms, must be marked with ink (India ink, Mrs. Stewart's Bluing, green, and yellow). Both will go through processing, be visible in stained sections, and be helpful in the assessment of surgical margins for tumor. Methods of blocking tissue for assessment of tumor in the surgical margins are shown in the following Figure. Please call the attending pathologist for questions.
5. Extremely small specimens (e.g. trabeculectomies and epiretinal membranes) should be marked with tissue dye (to permit visualization by technologist) and then placed carefully in an embedding bag.
6. Finally, one can instruct the technologist to "call me when embedding" and thereby control the embedment and sectioning.
NOTE: ALWAYS KEEP THE PAPER WORK, (routing form) WITH THE SPECIMEN. IF THE PAPER WORK IS SUBMITTED FOR TYPING, MAKE SURE A COPY STAYS WITH THE SPECIMEN. Your sections will return with the routing form. Keep slides and paperwork together until after sign out.