凡纳滨对虾白便综合征的组织病理学观察

本文比较观察了不同规格的健康和患白便综合征凡纳滨对虾Litopenaeus vannamei肝胰腺、中肠、后肠、后盲囊等的组织结构。组织病理显示:白便综合征凡纳滨对虾肠道严重病变,肠腔空,环肌两侧增生大量成纤维细胞,这些增生细胞取代了肠上皮,而不见正常柱状上皮细胞;肝胰腺有不同程度和性质的病变,如腺管萎缩、崩解、坏死等。凡纳滨对虾患白便综合征的组织病变演变过程为:最初肠上皮基膜下出现一圈增生细胞,肠上皮柱状细胞脱离基膜;增生细胞持续增生增多,肠上皮崩解脱落至肠腔,增生细胞完全取代肠上皮;增生细胞不断增生,增生细胞层逐渐变厚,随着时间的推移,增生细胞层近腔端的一圈增生细胞坏死,出现一圈棕黄色物质,最终坏死细胞连同棕黄色物质脱落至肠腔。脱落至肠腔的腺管细胞、上皮细胞、增生细胞排出体外即为肉眼可见的白便。

Histopathological Observation of Tissues in Pacific White Leg Shrimp Litopenaeus vannamei with White Feces Syndrome

Comparative histopathological observation of hepatopancreas,intestine and posterior caecus was conducted between healthy and sick Pacific white leg shrimp Litopenaeus vannamei with white feces syndrome and different sizes.It was found that great damage was observed in the diseased shrimp including heavy proliferation of fibroblasts in both sides of circular muscle,and intestinal epithelia replaced by the fibroblasts,and devoid of intestinal cavity,without columnar epithelial cells in the intestine of Pacific white leg shrimp with white feces syndrome.There were also different pathological changes in hepatopancreas,such as atrophy,disintegration and necrosis.Comparative observation at different developmental stages of white feces syndrome revealed that the white feces syndrome was developed as follows:first proliferative cells appeared under the basement membrane of intestinal epithelium separated from the basement membrane;proliferative cells continued to be increased in quantity,and intestinal epithelium collapsed and completely replaced by the proliferative cells and shed into the intestinal lumen;proliferative cells continued to be increased and then cell layer became thicker,necrosis and brownish yellow substances near the lumen appeared,eventually necrotic cells together with the brownish yellow substances shed into the intestinal lumen,until no proliferative cells were found.The white feces observed by the naked eyes were shown to be composed of pancreatic epithelial cells,intestinal epithelial cells and proliferative cells,which were discharged into the intestinal lumen.