ULTRASTRUCTURE OF ADULT GONADS AND DEVELOPMENT AND STRUCTURE OF THE LARVA OF RHABDOPLEURA-NORMANI (HEMICHORDATA, PTEROBRANCHIA)
ULTRASTRUCTURE OF ADULT GONADS AND DEVELOPMENT AND STRUCTURE OF THE LARVA OF RHABDOPLEURA-NORMANI (HEMICHORDATA, PTEROBRANCHIA)
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DOI：
10.1111/j.1463-6395.1988.tb00906.x
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发表时间：
1988-01-01
期刊：
影响因子：
1.2
通讯作者：
LESTER, SM
中科院分区：
文献类型：
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作者：
LESTER, SM
对采自百慕大群岛的横纹鳍鳃金龟（Rhabdopleura normani）性成熟成虫、胚胎和幼虫进行了光镜和电镜观察。在一个群体的动物体内，两性是分开的，但一个给定的群体可能包含雌性和雄性。在任一性别的动物体中，单一的性腺与躯干囊中的大血窦相关联，并且侧向移位（向右或向左）。生殖腺壁由三层组成：外层的代谢体腹膜、内层的生殖腺上皮和中间的生殖血窦。成熟的配子位于生殖腺内腔中。精子的特征是核细长，无明显的顶体，中段附件中有一条长的线粒体丝，单个鞭毛，轴丝为9 + 2。雌性在其独特的基部卷曲管中孵育200 μ m的卵和胚胎。卵黄卵经历放射状卵裂并发育成纤毛的、卵营养的、椭圆形的幼虫（长400 μ m），其特征在于：（1）黄色着色，点缀着黑色色素点;（2）深腹凹陷;（3）后部粘附器官;（4）前部顶端感觉器官;（5）均匀纤毛的表皮。腹凹不是内陷的内胚层，而是腺上皮，明显分泌幼虫茧和成虫管。在内部，体腔的腹膜开始从一个大的，中央的卵黄间充质细胞群的外围分裂。幼虫利用纤毛游泳，但也经历收缩，显然是由构成肌上皮的腹膜细胞提供动力。讨论认为，与其他后口动物和lophophorates翼鳃类的亲和力。
Sexually mature adults, embryos and larvae of the pterobranch Rhabdopleura normani from Bermuda were studied with light and electron microscopy. The sexes are separate among the zooids of a colony, but a given colony may contain females and males. In zooids of either sex the single gonad is associated with a large haemal sinus in the trunk sac and is displaced laterally (to the right or to the left). The wall of the gonad is composed of three layers: an outer metasomal peritoneum, an internal linning of germinal epithelium and an intervening genital haemal sinus. The mature gametes lie in the lumen within the gonad. The spermatozoon is characterized by an elongate nucleus, no obvious acrosome, a long mitochondrial filament in a midpiece appendix and a single flagellum with a 9 + 2 axoneme. Females brood 200 .mu.m eggs and embryos in their distinctive, basally coiled tubes. The yolky eggs undergo radial cleavage and develop into ciliated, lecithotrophic, oblong larvae (400 .mu.m in length) that are characterized by: (1) yellow coloration peppered with black pigment spots; (2) a deep ventral depression: (3) a posterior adhesive organs; (4) an anterior apical sensory organ; (5) an evenly ciliated epidermis. The ventral depression is not invaginating endoderm, but is instead a glandular epithelium that evidently secretes the larval cocoon and the adult tube. Internally, the peritoneum of the coelomic cavities begins to split from the periphery of a large, central mass of yolky mesenchyme cells. The larva swims using cilia, but also undergoes contractions, evidently powered by the peritoneal cells, which constitute a myoepithelium. The discussion considers pterobranch affinities with other deuterostomes and with lophophorates.