弓形革囊星虫组织结构和超微结构观察

弓形革囊星虫(Phascolosoma arcuatum)是近年兴起的水产养殖品种,目前已形成一定养殖规模,但是其生物学特性相关的研究只有零星报道。本文主要采用石蜡切片苏木精-伊红(H.E)染色和扫描电镜方法对弓形革囊星虫的整体形态和各主要器官的结构进行研究。结果表明,弓形革囊星虫主要由吻部和躯干部构成,躯干部有乳突分布;吻部由触手和项器构成,伸长可达躯干部的两倍,具有感光性。其消化系统由口、食道、肠、肛门四个部分构成,不同部分的肌肉组织存在明显差异;收吻肌一端与吻相连,另一端分成4支,分别连于背部两侧(背收吻肌)和腹部两侧(腹收吻肌);食道贴于收吻肌,后连接肠。肠分为肠下回环与肠上回环,肠上回环与肠下回环缠绕盘旋,肠上回环后接直肠。直肠具有盲囊,后连接肛门;两条肾管分布在腹侧。

The Morphological Structure and Ultrastructure of Sipunculan Worm (Phascolosoma arcuatum)

Sipunculan worm (Phascolosoma arcuatum) is an emerging cultural species in recent years. Even though its artificial culture has been expanded, little is known about its biological characteristics. In this paper, the morphological structure and ultrastructure of Sipunculan worm were elucidated by hematoxylin-eosin staining method and scanning electron microscopy, respectively. The results showed that Sipunculan worm was mainly divided into introvert part and trunk parts. The trunk was armed with mastoid, while the introvert was flexible and could be elongated to the length about twice of that of the trunk. The introvert consisted of tentacles and nuchal organ (Fig. 1a). The digestive system of the Sipunculan worm was composed of four parts: mouth, esophagus, intestine and anus (Fig. 4), and the morphology of muscle tissues in the latter three parts was significantly different (Fig. 6). One terminal of the muscle was connected to the introvert (named introvert muscle), while the other terminal of the muscle was divided into 4 branches. Two of the branches were connected to the ventral part (named ventral retractor muscle), while the other two of the branches were connected to the dorsal part (named dorsal retractor muscle). The esophagus was attached to the introvert muscle and it was connected to the intestine. The intestine was divided into ascending loop and descending loop. The ascending loop and descending loop were winding and circling, the terminal of descending loop was linked to the rectum with a rectal blind sac, and eventually it was connected to the anus. There were two nephridium tubes existing in the ventral part (Fig.1b).