Thomas G, Stender-Seidel S
Zoologisches Institut, Arbeitsgruppe Parasitologie, Kiel, Germany.
Parasitol Res. 1996;82(5):459-67. doi: 10.1007/s004360050145.
The foregut of Raillietiella sp. was investigated ultrastructurally in different ontogenetic stages: the embryo prior to hatching, the first-stage larva, the infective fourth-stage larva from the intermediate host, and juveniles and adults from the definitive host. As early as at the embryo stage the chitinous mouth armature is highly specialized. During postembryogenesis this structure is modified until it reaches its final shape in the juvenile. The most important changes occur during the period of development from the infective larva to the juvenile, which is related to the change from the intermediate to the definitive host; only stages inhabiting the definitive host can use their mouth as a suction pump. Therefore, only juveniles and adults are capable of sucking blood, whereas larvae are dependent on accessible liquid food. The remaining foregut represents a conveyor tube, growing in width toward the midgut. From the juvenile stage onward the transition to the midgut is formed as a cardiac valve.
对雷氏绦虫属（Raillietiella sp.）前肠在不同发育阶段进行了超微结构研究：孵化前的胚胎、第一期幼虫、来自中间宿主的感染性第四期幼虫以及来自终末宿主的幼虫和成虫。早在胚胎阶段，几丁质化的口器就高度特化。在胚胎后期发育过程中，这种结构不断变化，直至在幼虫阶段达到最终形态。最重要的变化发生在从感染性幼虫发育到幼虫的阶段，这与从中间宿主转变为终末宿主有关；只有栖息在终末宿主中的阶段才能将口用作抽吸泵。因此，只有幼虫和成虫能够吸血，而幼虫则依赖于可获取的液体食物。其余的前肠是一个输送管，朝着中肠方向变宽。从幼虫阶段开始，向中肠的过渡形成了一个贲门瓣。
