The effect of prolonged fixation time on haematoxylin & eosin staining quality of rats colon and placenta tissue

• Main Authors: Mohd Radzuan, Hazulin, Saharudin, Shahida, Wan Omar, Wan Fatein Nabeila, Abd. Rahim, Nour El Huda, Halim, Mohd Dhiyaulhaq
• Format: Conference or Workshop Item
• Language: English; English
• Published: 2021
• Subjects: Q Science (General); QD Chemistry; QM Human anatomy; R Medicine (General)
• Online Access: http://irep.iium.edu.my/94042/1/IRD2021.pdf; http://irep.iium.edu.my/94042/2/ird2021%20ppt.pdf; http://irep.iium.edu.my/94042/
• Institution: Universiti Islam Antarabangsa Malaysia

The use of formalin in histopathological sample preparation is intended to preserve protein and cellular organelles. It is argued that prolonged formalin fixation may lead to tissue shrinkage and hardening. Reports on immunohistochemical studies showed that this does not cause reduction in antigen detection. However, it is not known if prolonged formalin fixation can affect hematoxylin and eosin (H&E) staining quality. Our aim is to evaluate the effect of formalin in two different fixation time towards the quality of H&E staining adequacy in paraffin-embedded tissue blocks. Samples from Sprague-Dawley female rats, which include colon and placenta tissues were harvested and processed to form formalin-fixed paraffin embedded blocks. They were assessed in two durations: standard duration (SD) fixation up to 72 hours and prolonged duration (PD) up to 7 months in 10% neutral-buffered formalin (NBF). Thirty tissue sections from each study group were stained in modified Gill’s haematoxylin, and counter-stained in eosin, before cover slipped with DPX. The slides were viewed with light microscope (Olympus BX51, Japan). We found that the staining quality was better among SD of placenta tissue as evidenced by basophilic appearance of basal spongiotrophoblast, and eosinophilic labyrinthine trophoblast. There was not much difference in term of staining quality for colon, only that more artifacts can be observed among PD histological sections. In conclusion, prolonged fixation of colon and placental tissues in 10% NBF caused low quality H&E staining. This could be attributed to diminished cellular organization and protein structure. The difference between solid tissue and hollow organ sample also may contribute to the result. As much as we need to optimize sustainable resources, it should not compromise the quality of the outcome. We recommend preserving histopathological samples by adhering to the standard 72 hours duration of formalin-fixation, and archiving samples as paraffin-embedded tissue block for future studies.