Tzetlin Alexander B
Department of Invertebrate Zoology, Biological Faculty, Moscow State University, Moscow, Russia.
J Morphol. 1998 Oct;238(1):93-107. doi: 10.1002/(SICI)1097-4687(199810)238:1<93::AID-JMOR8>3.0.CO;2-O.
The microscopic anatomy of giant pelagic larvae of Phyllodocidae was studied using routine histological, SEM, and TEM techniques. The larvae consist of two distinct regions: a large spherical trochophore measuring up to 2 mm in diameter and a posterior, long (up to 10 mm length), narrow rudiment of the adult body with up to 120 segments. The larvae have an unusual mixture of larval and adult features, including a very complex, well-developed brain and ganglia in the ventral nerve cord, and only a single pair of protonephridia located in the hyposphere of the trochophore. A muscular pharynx is not developed. The intestinal wall, especially in the trochophore region, consists of endodermal cells containing considerable nutritive material in the form of yolk-like globular inclusions. The digestive tract of all larvae was empty. The position of the frontal sensory organ and the prototroch, the structure of the parapodia and setae, and the three pairs of tentacular cirri dictate inclusion of the larvae in the family Phyllodocidae. The relatively enormous size and unusual pattern of development of the adult body may be adaptations for a long pelagic life and rapid settlement of the species, which inhabits slopes of islands and underwater mounts located far apart. J. Morphol. 238:93-107, 1998. © 1998 Wiley-Liss, Inc.
利用常规组织学、扫描电子显微镜和透射电子显微镜技术，对叶须虫科巨型浮游幼虫的微观解剖结构进行了研究。幼虫由两个不同的区域组成：一个直径达2毫米的大型球形担轮幼虫，以及一个后部的、长（长达10毫米）且窄的成体雏形，其具有多达120个体节。幼虫具有幼虫和成体特征的异常混合，包括腹神经索中非常复杂且发育良好的脑和神经节，并且在担轮幼虫的下球体中仅存在一对原肾管。肌肉质咽未发育。肠壁，特别是在担轮幼虫区域，由含有以卵黄样球状内含物形式存在的大量营养物质的内胚层细胞组成。所有幼虫的消化道都是空的。额感觉器官和原轮的位置、疣足和刚毛的结构以及三对触手状触须决定了这些幼虫属于叶须虫科。成体相对巨大的体型和不寻常的发育模式可能是对该物种漫长浮游生活和快速沉降的适应，该物种栖息于相距遥远的岛屿斜坡和水下海山。《形态学杂志》238:93 - 107，1998年。© 1998威利 - 利斯公司。
