Gross anatomy of the Pacific hagfish, Eptatretus burgeri, with special reference to the coelomic viscera
Gross anatomy of the Pacific hagfish, Eptatretus burgeri, with special reference to the coelomic viscera
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DOI：
10.1002/ar.25208
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发表时间：
2023-03-23
影响因子：
2
通讯作者：
Higashiyama，Hiroki
中科院分区：
文献类型：
--
作者：
Muramatsu，Banri;Suzuki，Daichi. G. G.;Higashiyama，Hiroki
盲鳗（Myxinoidea）是圆口目（Cyclostomes）的深海分类群，现存的无颌脊椎动物。许多研究人员研究了盲鳗的解剖学和胚胎学，以阐明脊椎动物的早期进化;然而，盲鳗内部的多样性往往被忽视。盲鳗有三个谱系，Myxininae，Eptatretinae和Rubicundinae。通常，教科书上的盲鳗解剖插图反映了Myxininae谱系的形态，特别是Myxinebuilosa，它有一对外部鳃孔。在这里，我们报告的大体解剖Eptatretinae，Eptatretus burgeri，其中有六对鳃孔，特别是侧重于体腔器官。对固定和未固定标本进行解剖，为进行器官或组织特异性分子实验提供指导。我们的解剖显示腹主动脉在E呈Y型分支。burgeri，不同于Myxine的无分支形态。除此之外，在咽部区域的舌器或心脏的形态没有差异。甲状腺滤泡分散在腹主动脉周围，与成年七鳃鳗的报告相同。与成年七鳃鳗相比，它们的肝胆系统更像有颌脊椎动物的肝胆系统，肝脏有两个叶，一个胆管将胆囊连接到每个叶。总体而言，E. burgeri在大体解剖学水平上与已知的Myxine没有显著差异，尽管与Myxine相比，鳃形态在遗传学上是祖先的。
Hagfish (Myxinoidea) are a deep‐sea taxon of cyclostomes, the extant jawless vertebrates. Many researchers have examined the anatomy and embryology of hagfish to shed light on the early evolution of vertebrates; however, the diversity within hagfish is often overlooked. Hagfish have three lineages, Myxininae, Eptatretinae, and Rubicundinae. Usually, textbook illustrations of hagfish anatomy reflect the morphology of the Myxininae lineage, especiallyMyxine glutinosa, with its single pair of external branchial pores. Here, we instead report the gross anatomy of an Eptatretinae,Eptatretus burgeri, which has six pairs of branchial pores, especially focusing on the coelomic organs. Dissections were performed on fixed and unfixed specimens to provide a guide for those doing organ‐ or tissue‐specific molecular experiments. Our dissections revealed that the ventral aorta is Y‐branched inE. burgeri, which differs from the unbranched morphology ofMyxine. Otherwise, there were no differences in the morphology of the lingual apparatus or heart in the pharyngeal domain. The thyroid follicles were scattered around the ventral aorta, as has been reported for adult lampreys. The hepatobiliary system more closely resembled those of jawed vertebrates than those of adult lampreys, with the liver having two lobes and a bile duct connecting the gallbladder to each lobe. Overall, the visceral morphology ofE. burgeridoes not differ significantly from that of the knownMyxineat the level of gross anatomy, although the branchial morphology is phylogenetically ancestral compared toMyxine.