Rate of autolytic changes in different unfixed tissues at different time interval

Abstract

Aim and Background: Fixation hardens tissues and stabilizes the protein skeleton of the cell by giving the cell some structural support to resist deformation or crushing which may occur in the tissue processing sequence. Since fixation is essential for optimum tissue preparation for sectioning, it is worthwhile to study the autolytic changes in tissues which may affect this stage of specimen handling.

Method: A healthy six-month old Wister rat was anaesthetized with chloroform, killed and dissected to aseptically harvest the brain, lung and liver. These organs were cut into 10 sections, each of 2×2×3mm, transferred into sterile universal containers from where sections were removed and fixed in 10% formal saline at a two hour intervals from 0 hours to 18 hours. Haematoxylin and Eosin and Gram’s Iodine stain were used to stain all the sections obtained from tissue blocks, Periodic acid Schiff’s (PAS) for the section of liver tissue, Verhoff elastic fibre stain for lungs section and Bielschowsky’s stain for brain tissue section.

Results: Putrefaction in the brain was noticeable within 8 hours, in the liver it started at the 14th hour while putrefaction was absent in the lungs.

Conclusion: Optimal staining reaction in brain and liver tissues would be unrewarding if the tissue is not fixed within 4 hours while the lung biopsy must be fixed within 6 hours.

Keywords: Putrefaction; Autolysis; Fixation; Tissue