Fixation on Histology

4 Seasons in One Laboratory

We, histology Laboratory professionals, have our own language that we use when we meet that no one knows how to communicate with except us. Our communication  is simple and closely tightened by the chain known as NSH. That is why we feel a sense of humor when someone in the group posts “things only a Histology laboratory professional understands” and we either smile or laugh.

Have you ever thought about how climate impacts a histology laboratory? You have two distinct “seasons” at one piece of equipment, the embedding machine. It contains summer (heat) and winter (snow) at the same time. The hot plate reaches 55 to 60 degrees celsius and the cold plate reaches the snow season. After completion of the staining, the slides at the table look like attractive flowers in the fall .

Have you ever thought about how season has an effect on the change of morphological, histo-cytological, and hormonal parameters of the thyroid gland in cattle? A study in Algeria concluded that; microscopic examination of histological sections of the thyroid glands of cattle consists of a capsule and parenchyma. Septae submerge in the parenchyma, dividing it into compartments. Analytical biochemistry has proven that the concentration of thyroid hormones was high in cows during the summer period.

Figure 1 shows the Histological section of cow thyroid gland hematoxylin and eosin staining magnification X40. 

  • Histological section of the bovine thyroid gland from the summer season.
  • Histological section of the bovine thyroid gland from the winter season

(Flc=follicles, E=Interfollicular area, Cl=colloid, thyrocytes presented by arrows)

There is also another factor that negatively affects the capability of diagnosing the tissue due to freezing artifact.  When fixed tissues freeze, it causes ice crystals to form in the tissues and “crack” the tissues. The ice expands and pulls apart the tissues, then when they thaw, the gap in the tissue remains. This artifact makes it difficult to impossible for the anatomic pathologist to provide a diagnosis for your patient.  See image below.

What are your experiences or any evidence on the effect of climate at your lab?! Does season affect your turnaround time (TAT) ? Quality? Activity? Do you adjust your laboratory room temperature accordingly? What are the guidelines for the adjustment of your room?

As you experience the “seasons”, think about how the climate may impact your work and make the adjustments accordingly.


Rahmoun DE, Fares MA, Gherissi DE, Lieshchova M (2020) Effect of the Seasons on the Change of Morphological, Histo-Cytological and Hormonal Parameters of the Thyroid Gland in Cattle in Algeria. J Vet Sci Ani Husb 8(2): 203

Dr. Sasha T, Protecting Biopsy Samples from the Winter Freeze During Shipment, Kansas State Veterinary Diagnostic Laboratory, 2021, URL []

Written by: Giorgis Yeabyo , BS, MS, HTL (ASCP)