Table 2.

Intestinal histological variation of heat stressed O. stewarti juvenile with different acclimation histories.

Acclimation temperature (°C)	10	15	20
Heat stress for 0 h	The structure of intestinal mucosa was intact and no obvious pathological changes, such as inflammation, were found	The structure of intestinal mucosa was intact and no obvious pathological changes, such as inflammation, were found	The structure of intestinal mucosa was intact and no obvious pathological changes, such as inflammation, were found
Heat stress for 2 h	Some blood vessel lumen dilation can be seen in the muscular layer of intestinal tissue. Diffuse infiltration of lymphocytes was observed in the intestinal mucosa.	Diffuse infiltration of lymphocytes was observed in the intestinal mucosa.	Diffuse infiltration of lymphocytes was observed in the intestinal mucosa.
Heat stress for 6 h	Focal infiltration of lymphocytes can be seen in the mucosal layer of intestinal tissue. Local intestinal villi show epithelial cells necrosis and abscission. Some intestinal villi epithelial cells displayed edema, cell swelling, and cytoplasmic light staining.	Diffuse infiltration of lymphocytes was observed in the intestinal mucosa. Some intestinal villi epithelial cells displayed edema, cell swelling, and cytoplasmic light staining.	Local intestinal villi show epithelial cells necrosis and abscission. Some intestinal villi epithelial cells displayed edema, cell swelling, and cytoplasmic light staining.
Heat stress for 12 h		Local diffuse infiltration of lymphocytes can be seen in the mucosal layer of the tissue. Local intestinal villi show epithelial cells necrosis and abscission. Some intestinal villi epithelial cells display edema, cell swelling, and cytoplasmic light staining.	Local diffuse infiltration of lymphocytes can be seen in the mucosal layer of the tissue. Local intestinal villi show epithelial cells necrosis and abscission. Some intestinal villi epithelial cells display edema, cell swelling, and cytoplasmic light staining.