Mehlhorn H, Eckert J, Thompson R C
Z Parasitenkd. 1983;69(6):749-63. doi: 10.1007/BF00927424.
The larval stage (metacestode) of Echinococcus multilocularis was studied by means of electron microscopy (SEM, TEM) before and after subcutaneous transplantation to jirds (Meriones unguiculatus) and in their lymph nodes and lungs with parasite metastases. It was found that the metacestode consists of a network of solid, cellular protrusions (buds) of the germinal layer which transform to tube-like and cystic structures devoid or with a laminated layer. Proliferation of the metacestode apparently occurs by protruding filamentous solid cell columns (buds) from the germinal layer. Their tips have diameters of only one cell: they are covered with a smooth syncytial tegument without microtriches and are filled with undifferentiated cells which contain a nucleus with a large nucleolus. The tegument is constantly enlarged by fusion with the underlying undifferentiated cells that divide repeatedly. At some distance from the tip a cavity develops inside the protrusion, thus finally giving rise to a tube-like structure which may transform to a cystic expansion. Simultaneously, the surface of the protrusion changes by the formation of microtriches and the occurrence of an amorphous laminated layer. The latter is concentrically covered by connective tissue cells and large amounts of collagen. Within cyst-brood capsules, finally protoscoleces are formed from accumulations of undifferentiated cells beneath the tegument. The study has unequivocally proven the cestode nature of the cellular protrusions, and it is assumed that detachment of cells from these structures and their subsequent distribution via the circulation may play a role in the formation of metastases. The origin of the laminated layer is discussed.
利用电子显微镜（扫描电子显微镜、透射电子显微镜）对多房棘球绦虫的幼虫期（原头蚴）进行了研究，观察对象包括皮下移植到沙鼠（长爪沙鼠）体内前后的情况，以及有寄生虫转移灶的沙鼠淋巴结和肺组织。研究发现，原头蚴由生发层的实体细胞突起（芽体）网络组成，这些突起会转变为无分层或有分层的管状和囊状结构。原头蚴的增殖显然是通过生发层伸出丝状实体细胞柱（芽体）来实现的。它们的顶端直径仅为一个细胞大小：覆盖着一层光滑的合体皮层，没有微毛，内部充满未分化细胞，这些细胞含有一个有大核仁的细胞核。皮层通过与不断重复分裂的下层未分化细胞融合而持续扩大。在离顶端一定距离处，突起内部会形成一个腔，最终形成管状结构，该结构可能转变为囊状扩张。同时，突起表面会通过形成微毛和出现无定形分层而发生变化。后者被结缔组织细胞和大量胶原蛋白同心覆盖。在囊内育囊内，最终在皮层下方由未分化细胞聚集形成原头节。该研究明确证实了细胞突起的绦虫性质，并推测这些结构中的细胞脱离及其随后通过循环系统的分布可能在转移灶的形成中起作用。文中还讨论了分层的起源。
