Dudley Patricia L
Department of Biological Sciences, Barnard College, Columbia University, New York, New York 10027.
J Morphol. 1972 Dec;138(4):407-431. doi: 10.1002/jmor.1051380403.
A cephalic organ of presumed sensory function is described in nauplii and copepodids of the ascidicolous copepod Doropygus seclusus Illg. The receptor, located bilaterally in the anterodorsal head region, is composed of dendrites of extra optic protocerebral origin which have ciliary protrusions with basal bodies, no rootlets, and a basal infrastructure of the 9 + 0 type. The cilia do not branch and their distal terminations contain only one to four microtubules. In nauplii and free-living copepodids, a large epidermal supporting cell encapsulates the end of one dendrite and its cilia in a sac. Other dendrites and their cilia pass through the supporting cell and, terminally, the cilia escape to form a whorled fascicle which contacts the anterolateral cephalic cuticle. The latter end organ reaches its greatest development in the second copepodid stage - the stage which infects the ascidian. All of the symbiotic stages of the copepod have only a proportionately smaller end organ of the saccular type and apparently lack the end organ consisting of whorls of ciliary ends. The function of the receptor is unknown, but it is suggested that the end organ which disappears in the symbiotic stages functions in second copepodids in host recognition.
在寄生性桡足类动物隐居多肋桡足虫（Doropygus seclusus Illg）的无节幼体和桡足幼体中，描述了一个推测具有感觉功能的头部器官。该感受器双侧位于头部前背区域，由视外原脑起源的树突组成，这些树突具有带基体的纤毛突起，无小根，且基部结构为9 + 0型。纤毛不分枝，其远端仅含有一至四根微管。在无节幼体和自由生活的桡足幼体中，一个大的表皮支持细胞将一个树突及其纤毛的末端包裹在一个囊中。其他树突及其纤毛穿过支持细胞，最终，纤毛伸出形成一个轮状束，与头部前外侧角质层接触。后一种终末器官在桡足幼体的第二个阶段——即感染海鞘的阶段——发育到最大程度。桡足类动物的所有共生阶段都只有比例上较小的囊状终末器官，显然缺乏由纤毛末端的轮状物组成的终末器官。该感受器的功能尚不清楚，但有人认为在共生阶段消失的终末器官在桡足幼体的第二个阶段在宿主识别中起作用。
