Fine structure of the retrocerebral organ in the rotifer Trichocerca similis (Monogononta)
Fine structure of the retrocerebral organ in the rotifer Trichocerca similis (Monogononta)
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DOI：
10.1111/ivb.12396
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发表时间：
2023-03-10
影响因子：
1.2
通讯作者：
Wallace，Robert L.
中科院分区：
文献类型：
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作者：
Hochberg，Rick;Araujo，Thiago Q.;Wallace，Robert L.
脑后器官（RCO）是一个复杂的腺体系统，广泛分布于轮虫门（狭义）的各个物种。该系统被假设为分泌有助于底栖动物运动、粘附和/或繁殖的粘液。不幸的是，RCO的超微结构大多是未知的，只有一个物种进行了部分研究。我们用透射电镜和激光共聚焦扫描显微镜对淡水轮虫Trichocerca similis的RCO进行了研究。结果显示，RCO是一个单一的合胞体器官，由一个后腺区，一个膨胀的水库，和一个前导管。腺体部分有一个活跃的合成细胞质，有成对的核，丰富的rER，核糖体，高尔基体和线粒体。电子致密的分泌颗粒积聚在腺体的前端，并进行同型融合，以产生更大，更电子透明的颗粒，具有许多网状内容物，逐渐融合成管状分泌物，积聚在储库中。这些分泌物的超微结构表明它们可能是水合糖蛋白。横纹纵肌在储液囊周围形成部分袖套，其功能可能是通过穿透脑神经节的单个胞质导管挤压分泌物。从其他轮虫的RCOs的审查表明，进一步的超微结构分析之前，需要试图辨别其功能和同源性。
The retrocerebral organ (RCO) is a complex glandular system that is widely distributed across species of phylum Rotifera (sensu stricto). This system is hypothesized to secrete mucus that aids in benthic locomotion, adhesion, and/or reproduction. Unfortunately, the ultrastructure of the RCO is mostly unknown, having only been partially examined in one species. We used transmission electron microscopy and confocal laser scanning microscopy to describe the RCO in the planktonic freshwater rotiferTrichocerca similis. Results reveal the RCO to be a singular syncytial organ composed of a posterior glandular region, an expansive reservoir, and an anterior duct. The glandular portion has an active synthetic cytoplasm with paired nuclei, abundant rER, ribosomes, Golgi, and mitochondria. Electron‐dense secretion granules accumulate at the anterior end of the gland and undergo homotypic fusion to create larger, more electron‐lucent granules with numerous mesh‐like contents that gradually fuse into tubular secretions that accumulate in the reservoir. Ultrastructure of these secretions suggests they may be hydrated glycoproteins. Cross‐striated longitudinal muscles form a partial sleeve around the reservoir and may function to squeeze the secretions through the single cytoplasmic duct that penetrates the cerebral ganglion. A review of the RCOs from other rotifers suggests that further ultrastructural analyses are required before attempting to discern their functions and homologies.