Fahrner A, Haszprunar G
Institute of Zoology, Ludwig-Maximilians University, Munich, Germany.
J Submicrosc Cytol Pathol. 2000 Apr;32(2):185-94.
The microanatomy and ultrastructure of the excretory system of Pneumoderma sp. (Gymnosomata) and Creseis virgula Rang, 1828 (Thecosomata) have been investigated by means of semithin serial sections, reconstructions and transmission electron microscopy. The studies revealed a functional metanephridial system consisting of a heart with a single ventricle and auricle in a pericardial cavity and a single kidney in both species. Podocytes in the atrial wall of the pericardial epithelium are the site of ultrafiltration, whereas the flat epithelium of the kidney with numerous basal infoldings and a dense microvillous border on the luminal surface suggests modification of the ultrafiltrate. In Pneumoderma sp., additional loci of ultrafiltration with identical fine structure (meandering slits with diaphragms covered by extracellular matrix) occur in the solitary rhogocytes (pore cells). The presence of podocytes situated on the atrial wall in representatives of two higher opisthobranch taxa contradicts former ideas on the loss of the primary site of ultrafiltration in the ancestors of the Opisthobranchia.
通过半薄连续切片、重建和透射电子显微镜对裸鳃目动物肺皮虫属（Gymnosomata）和1828年的克里西斯·维尔古拉·朗（Thecosomata）排泄系统的微观解剖结构和超微结构进行了研究。研究发现，这两个物种都有一个功能性的后肾系统，包括位于心包腔内的一个单心室和心耳的心脏以及一个单一的肾脏。心包上皮心房壁中的足细胞是超滤的部位，而肾脏的扁平上皮具有许多基底褶皱和管腔表面密集的微绒毛边界，表明超滤液发生了改变。在肺皮虫属中，具有相同精细结构（有隔膜的曲折缝隙被细胞外基质覆盖）的额外超滤位点出现在单个的菱形细胞（孔细胞）中。在两个较高等的后鳃类群的代表中，心房壁上存在足细胞，这与以前关于后鳃类祖先中超滤主要部位丧失的观点相矛盾。
