The division of different stages of aestivation and quantitative analysis of tissue layers thickness of anterior intestine in sea cucumber Apostichopus japonicus
刺参夏眠不同时期划分以及前肠各组织层厚度定量分析

Non-aestivation stage sea cucumber as control group, three time points were selected according to aestivating degree in sea cucumber (Apostichopus japonicus): initial stage of aestivation, deep aestivation, and the arousal stage of aestivation. The diameter, thickness and different tissue layers thickness of anterior intestine at these three points were measured. As for the submucosa thickness, there was no significant difference between control group and any stage (P>0.05). As for mucous epithelium and the adventitia, the thickness of the initial stage of aestivation was significantly smaller than those of control group (P<0.05). At the deep aestivation stage, the thickness of mucous epithelium and muscular layer was significantly smaller than that of control group (P<0.01). The anterior intestine diameter at the deep aestivation stage was significantly smaller than that of control group (P<0.01). Calculating the proportion of each layer of the anterior intestine wall thickness, we found that the proportion of mucous epithelium and adventitia was significantly smaller at the initial stage than that of control group (P<0.05). However, the proportion of submucosa was significantly bigger at the initial stage than that of control group (P<0.01). The proportion of muscular layer was significantly smaller at the deep aestivation stage than any other stages (P<0.05).