梭子蟹肌孢虫的组织分布与形式特点

The tissue distribution and formal features of the Ameson sp. infecting Portunus trituberculatus

利用透射电镜技术研究了梭子蟹肌孢虫在三疣梭子蟹体内的组织分布和形式特点,结果显示,梭子蟹肌孢虫主要寄生在骨骼肌、血淋巴、鳃、胃和肠,而在心脏、肝胰腺、性腺和神经等部位未发现。在胃和肠的结缔组织以及骨骼肌中发现梭子蟹肌孢虫的分裂体,表明其可以在这些组织的细胞中增殖,尤其是在骨骼肌细胞中,大量不同发育时期的虫体显示了该虫对骨骼肌的亲嗜性。梭子蟹肌孢虫的分裂体以及其他增殖期的细胞仅寄生于宿主细胞内,而成熟的孢子可存在于宿主细胞内和细胞外基质中。梭子蟹肌孢虫的孢子有6种存在形式,在宿主细胞内和宿主细胞外基质中各有3种。孢子在宿主细胞内的存在形式:1孢子直接寄生于宿主细胞质中,自由游离,无膜包围;2孢子被单层膜包围,类微绒毛样突起物部分溶解,这种情况见于专业性吞噬细胞——无颗粒细胞内;3孢子被层状环形膜结构包围,类微绒毛样突起物清晰,这种情况见于非专业性吞噬细胞内。孢子在宿主细胞外基质中的存在形式:1孢子自由游离,无膜包围,类微绒毛样突起物清晰;2多个孢子被体液性被囊包围,类微绒毛样突起物清晰;3孢子无膜包围,孢外壁与类微绒毛样突起物消失。本研究阐明了梭子蟹肌孢虫在三疣梭子蟹体内的组织分布和孢子的存在形式,为进一步研究微孢子虫在宿主蟹体内的迁移规律提供了重要的基础数据。

The method of transmission electron microscope was used to study the tissue distribution and formal characteristics of the microsporidian, Ameson sp. in the host Portunus trituberculatus. The results showed that the microsporidians were distributed mainly in the skeletal muscle, hemolymph, stomach and gut, no found in the heart, hepatopancreas, gonad and nervous tissues. Some meronts were found in the host skeletal muscle,connective tissue of the stomach and gut, indicating that the microsporidian was able to multiply in these tissues,especially in the skeletal muscle cells.A large number of microsporidians of different periods implied the tissue tropism of this microsporidian. The meronts and other multiplicative cells of the microsporidian were observed only in host cells, and the mature spores could exist within host cells and extracelluar matrix. A total of six existing forms of mature spores were found. The three within host cells： 1 The free spore without a membrane surrounding directly parasitized within the host cytoplasm. 2 The spore was surrounded by a single membrane with the microvilli-like projections partly dissolved. This form was generally observed within an agranular cell（i.e.the professional phagocyte）. 3 The spore was surrounded by lamellar membranous whorls and the microvilli-like projections was clearly visible. This form was found in nonprofessional phagocytes. The three within the host extracelluar matrix： 1 The spore was free without a membrane surrounding. The microvilli-like projections were clearly visible. 2 Several spores were surrounded by a humoral encapsulation. The microvilli-like projections were clearly visible. 3 The spore was free without a membrane surrounding. The exospore and microvilli-like projections both disappeared. The present study sheds light on the tissue distribution of microsporidian and existing form of the spore, and provides important data for the further study on the migration of microsporidia in the crab.