Siboglinum fiordicum (Annelida, Siboglinidae) 滋生动物的颈项器官,Journal of Experimental Zoology-B: Molecular and Developmental Evolution

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Siboglinum fiordicum (Annelida, Siboglinidae) 滋生动物的颈项器官
Journal of Experimental Zoology-B: Molecular and Developmental Evolution ( IF 1.8 ) Pub Date : 2023-03-01 , DOI: 10.1002/jez.b.23192
Elena Temereva _{1,

2} , Nadezhda Rimskaya-Korsakova ₁

Affiliation

颈项器官是存在于大多数环节动物中的表皮感觉结构。根据其中一种解释，它们服务于幼虫定居点。Siboglinids 在成虫和幼虫阶段缺乏颈部器官，但是，一些栖息在渗漏和热液喷口中的 siboglinids 的幼虫能够游到远离它们的家庭热液场 100 公里的地方，以在新的热液场定居。剩下的一个问题是，siboglinid 幼虫使用什么器官来搜索和定位合适的底物？为了确定 siboglinid 幼虫中是否存在任何颈部器官，我们研究了 frenulate Siboglinum fiordicum连续幼虫阶段的头部和感觉器官(Webb, 1963)，使用透射电子显微镜和免疫细胞化学。在早期的转子阶段，我们发现一个不成对的背侧器官位于后原转子的近端。该器官由滋养细胞和“覆盖”细胞组成。Trochoblasts 表现出血清素样免疫反应性，可能对应于纤毛支持细胞，其中纤毛和微绒毛投射到嗅觉室中。“覆盖”细胞的特点是存在大细胞核，细胞核有许多孔和突出到嗅觉室的粗突起，形成与滋养细胞突起的接触。我们首次证明早在轮叶动物阶段就在环节动物中存在类似颈项的器官。

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Nuchal organs in the trochophore of Siboglinum fiordicum (Annelida, Siboglinidae)

Nuchal organs are epidermal sensory structures present in most annelids. Based on one of the interpretations, they serve in larval settlement. Siboglinids lack nuchal organs in adult and larval stages, however, larvae of some siboglinids inhabiting seeps and hydrothermal vents are capable of swimming up to 100 km away from their home hydrothermal field to colonize a new one. One question that remains is, what organ are siboglinid larvae using to search and locate suitable substrates? To determine if any nuchal organs are present in siboglinid larvae, we studied the head and sensory apparatus in successive larval stages in a frenulate, Siboglinum fiordicum (Webb, 1963), using transmission electron microscopy and immunocytochemistry. In the early trochophore stage, we found an unpaired dorsal organ lying proximal to the posterior prototroch. This organ consists of trochoblast- and “covering” cells. Trochoblasts exhibited serotonin-like immunoreactivity and likely correspond to ciliated supporting cells, where cilia and microvilli project into the olfactory chamber. The “covering” cells are characterized by the presence of large nuclei with numerous pores and thick processes that project into the olfactory chamber, forming the contacts with the trochoblast projections. We have shown for the first time the presence of a nuchal-like organ in annelids as early as the trochophore stage. The presence of this organ in siboglinid trochophores while they are still in the inside the female tube suggests that this structure might be associated with functions other than settlement, such as communication or initiation of the departure from her tube.

更新日期：2023-03-01

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