4th week

hello! i've been posted to Histopathology. Honestly, i feel that it has been an intriguing month. i feel blessed to be embarking on this mirthful journey with Ernest and Ying Chee. Being part of the Histopathology Lab has helped paint a picture of what Histopathology is all about. Htech finally makes more sense now. Since i am in a routine lab, i shall focus more about embedding for this week. However these are the events in Histopathology Lab:

1. Specimens from a surgery are sent to the Specimens Receiving room. These specimens are kept in containers filled with formalin. Each specimen is allocated a biopsy number.

2. Specimens are transported into the trimming room. The larger specimens such as breast, colon, liver, lungs are trimmed by pathologists. On the other hand, the smaller specimens are handled by the medical technologists as they do not require trimming of any sort. The medical technologists have to solely place the small tissues into filter papers and subsequently into cassettes. This is to ensure that they are not lost when placed into the tissue processor. The area of interest of the larger specimens are trimmed and placed into cassettes. For example, for a breast specimen, one of the most important area is the lymph nodes. Hence the lymph nodes are extremely sort after by the pathologists. The pathologists will practically be frisking for the lymph nodes as they are rather minute. The cassettes are then shut and placed into a container of formalin. This is done by the medical technologist assisting the pathologist. Also, biopsy number is written on each cassette containing any tissue by the med tech. The med tech must also record the name of the pathologist performing the trim and the number of cassettes used for the case.

3. The container of formalin filled with cassettes will be placed into the tissue processor for 9.5 hours.

4. The tissues are then ready for embedding. This is the part which i would like to discuss in my entry. This is because i have been observing how embedding is done for about a week and ulteriorly i was given the chance to embed the specimens myself. With close supervision, for sure.

a) Depending on the size of the tissue, a suitable mold is chosen.Retrieved July 19, 2008, from,

http://www.leitzmicro.com/website/products.nsf?open&language=english&path=/website/products.nsf/(allids)/77de5e12c4f02672c1256a72004c1348

b) The mold is partially filled with wax. The mold is placed on the cold plate and the tissue is orientated in the mold. This has to be done simultaneously to ensure that the wax does not cool down completely before the tissues are properly orientated. If that happens, the position of tissue in the cooled wax will be uneven and this will hinder smooth-sailing sectioning during microtomy later. The mold is placed on the cold plate to provide a "third hand". When the wax is partially cooled, the tissue will not be floating around. By the way, the tissue is picked up from the cassette and into the mold using an electrically heated forceps. As it is hot, the chances of tiny tissues getting stuck on the forceps are arguably zilch. Henceforth, using those forceps hinders contamination.

Retrieved July 19, 2008, from,

http://www.leitzmicro.com/website/products.nsf?open&language=english&path=/website/products.nsf/(allids)/0215b39eb7698a5641256ab60036fc0f


Even the way tissues are orientated is crucial. Take cyst for example, the cyst wall is the part of interest. Therefore, when embedding, the cyst wall must be at the base of the mold. The senior med tech termed is as "block standing". When embedding, i believe the most important reminder to note is, to ensure that the tissues are pressed flat down. Of course, this has to be performed gently to prevent any smashed tissues as a result. The cover of the cassette is discarded while the base of the cassette is placed on top on the mold. Wax is dispensed for the second time above the cassette.

c) The mold is then placed on the cold plate until the wax is fully cooled. When the wax has wholly cooled down, the tissue block can be removed from the mold easily.




5) The tissue block is sectioned using the microtome.

6) The tissue is placed in the waterbath for fishing.

7) The slide is dried on the hot plate.

8) The slide is loaded into the H&E autostainer.

9) Slides are sent for sorting to be sent to the various pathologists for examination.



Nurathirah
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