2.3. Observation of frozen slices
Every eighth day, tilapia slices were obtained using a freezing
microtome (Model CM 1900, Leica Co. Ltd., USA). The blocks was
fixed with optimum cutting temperature embedding agent and cut
into slices with a thickness of 20 mm. Then, the slices were transferred
to a glass slide and stained according to H&E method (Ma,
Wu, Gao, Wang, Zhan, & Li, 2014; Supiwong et al., 2013). The
stained slices were observed using an optical microscope (BX51;
Olympus, USA) at a magnification of 50x