Digestive system of the sacoglossan Plakobranchus ocellatus (Gastropoda: Opisthobranchia):: Light- and electron-microscopic observations with remarks on chloroplast retention
Digestive system of the sacoglossan Plakobranchus ocellatus (Gastropoda: Opisthobranchia):: Light- and electron-microscopic observations with remarks on chloroplast retention
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DOI：
10.2108/zsj.22.905
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发表时间：
2005-08-01
影响因子：
0.9
通讯作者：
Hirose, Euichi
中科院分区：
文献类型：
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作者：
Hirose, Euichi
草鱼通过从藻类中吸取细胞质内容物来取食，并将完整的藻类叶绿体保留在消化腺的细胞内。首次用组织学和电子显微镜(扫描电子显微镜和电子显微镜)相结合的方法描述了该物种整个消化系统的形态。较短的消化道局限于头部，而肛门在心包肿胀的右前角开口，就像许多无壳的舌癌一样。被检查的标本的消化道中很少含有Instera，这表明保留的叶绿体为Socoglossan宿主提供了足够的营养，空腹的海参在野外生存得很好。消化腺具有保留的叶绿体，从胃开始分支，稀疏地分布于全身，包括头部，但主要聚集在背板。在从胃壁到消化腺的过渡区的上皮细胞中偶见叶绿体，这可能是叶绿体通过内吞作用进入动物细胞的部位。大量的微绒毛填充在消化腺的管腔中，表明分子在腺体内活跃地转移。因此，海参显然为叶绿体的长期保留和功能提供了有利的环境。
The sacoglossan Plakobranchus ocellatus feeds by sucking the cytoplasmic contents from algae and retains intact algal chloroplasts within the cells of the digestive gland. Morphology of the entire digestive system of this species was firstly described by means of a combination of histology and electron microscopy (both SEM and TEM). The short alimentary canal is confined to the head, and the anus opens at the anterior right corner of the pericardial swelling, as is the case in many non-shelled sacoglossans. The alimentary canal of the specimens examined rarely contained ingesta, suggesting that the retained chloroplasts provide sufficient nourishment to the sacoglossan hosts and that sea slugs with empty stomachs survive well in the field. The digestive gland, with the retained chloroplasts, branches from the stomach and is sparsely distributed throughout the body, including the head region, but is aggregated mainly in the dorsal lamellae. Chloroplasts were occasionally found in the epithelial cells in the transitional region from the stomach wall to the digestive gland, which may be a site at which chloroplasts are incorporated into the animal cells by endocytosis. Numerous microvilli filling the lumen of the digestive gland suggest that molecules are actively transferred within the gland. The sea slug thus apparently provides a favorable environment to support the long-term retention and function of chloroplasts.