中间球海胆体腔细胞损失后的恢复规律及恢复期中轴器观察

本研究通过人工抽离中间球海胆(Strongylocentrotus intermedius)体质量10%的体腔液诱导体腔细胞的修复更新，分组测定6、12、18和24 h后海胆围脏腔内的体腔细胞密度，分析体腔细胞的修复规律；同时，取各时间点海胆的中轴器进行组织学观察，并利用鼠抗人Ki-67(细胞增殖抗原)单克隆抗体检测中轴器内的细胞增殖信号。结果显示，人工抽离体腔液后6 h，体腔细胞密度与初始密度相比明显偏低；12 h后逐步升高，密度略低于初始密度，恢复度为(92.78±29.40)%；18 h后已明显高于初始密度，恢复度为(137.08±32.40)%，显著高于6 h和12 h的恢复度(P<0.05)，随后，体腔细胞密度逐渐降低。海胆损失体腔液后，中轴器表现为内部组织消减、空腔化，外壁上皮细胞层崩解、脱离，凸起结构空泡化等变化，18 h后内部疏松组织略有增加，24 h后中央腔内出现明显的新生组织。利用Ki-67单克隆抗体检测发现，正常海胆中轴器内具有一定的细胞增殖信号，该信号在损失体腔细胞18 h后明显增强。结果表明，损失体腔细胞后，中间球海胆可启动快速恢复机制，而海胆的中轴器发生明显的组织结构变化，组织内的细胞增殖活动也明显增强。研究结果可为海胆体腔细胞的造血组织与发生机制研究提供依据。

Recovery pattern of coelomocytes after loss in Strongylocentrotus intermedius and observation of axial organ during recovery phase

Similar to hemocytes in other species, coelomocytes of sea urchins play an important role in the immune system. A verification of the recovery pattern and origin of coelomocytes would be vital in understanding its immune mechanism. Axial organ is a glandular organ that has been thought to be the hemopoietic tissue of sea urchin. Using monoclonal antibodies against coelomocytes, we demonstrated in a previous study that axial organ could serve as a storage tissue of coelomocytes. We further investigated the recovery pattern of coelomocytes in the sea urchin Strongylocentrotus intermedius and the changes in the axial organ during the recovery phase. Coelomocyte density was examined at 6 h, 12 h, 18 h, and 24 h after manual extraction of 10% body weight of celomic fluid. Histology of the axial organ was observed, and cell proliferation activity was detected with a monoclonal antibody against Ki-67 (cell proliferation antigen). Results showed that the average coelomocyte density at 6 h was significantly lower than that before extraction; it gradually decreased at 12 h, with a density slightly lower than the initial level, with a recovery value of (92.78±29.40)%. Average coelomocyte was significantly higher than the initial level at 18 h, with a recovery value of (137.08±32.40)%, and was significantly higher than that at 6 h and 12 h (P<0.05). Subsequently, the coelomocyte density gradually decreased. The inter-tissue of the axial organ declined and cavitation occurred after coelomocytes were lost. The outer epithelial layer became loose and broke off, and vacuolation was observed in the bulges of the epithelial layer. The inter-tissue increased at 18 h, and newborn tissue appeared clearly at 24 h. Using the Ki-67 antibody, we found a cell production signal in the axial organ from the normal sea urchin and the signal was significantly enhanced after 18 h. Our results indicated that the restoring mechanism of coelomocytes could initiate rapidly after coelomocyte loss, while histological changes and cell production activity enhancement may occur in the axial organ. The present study provides valuable references for further research on the origin and ontogenesis of coelomocytes.