The ultrastructure of the protonephridial flame cell of the freshwater planarian Bdellocephala brunnea

Ishii, Saburo

doi:10.1007/bf00237973

Cited by 12 publications

(15 citation statements)

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“…Further studies are needed to clarify these complex threedimensional relationships between cyrtocyte and adjacent canal cells. This is also true for the cyrtocytes of the Tricladida, which appear, at first, quite different in their organization from the forms discussed above (see especially McKanna 1968;Ishii 1980a).…”

Section: Protonephridiamentioning

confidence: 87%

Morphology of the Turbellaria at the ultrastructural level

Rieger

1981

Hydrobiologia

112

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The paper reviews the following systems: body wall, nervous system, protonephridia, parenchyma, digestive system, reproductive system, and includes a summary of the literature. New information is presented for the catenulid and neoophoran body wall-construction, the kalyptorhynch proboscis, the catenulid and haplopharyngid protonephridial construction, and the prolecithophoran spermatozoon and female germ cell. Examples of new features, as well as examples of how electron microscopy has clarified the relative position of structures and their substructures are given from the subcellular level to the organization of whole organs. Fine structural features linking different turbellarian orders are summarized. They apparently support Karling's (1974) latest assessment of the affinities between the turbellarian orders which is based primarily on light histological data, they add the recognition of a special link between the Macrostomida and Haplopharyngida and they suggest the existence of three main evolutionary lines within the Turbellaria.

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Section: Protonephridiamentioning

confidence: 87%

Morphology of the Turbellaria at the ultrastructural level

Rieger

1981

Hydrobiologia

112

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“…The collapse of proximal arborizations concomitant with the loss of flame cells in intact EGFR-5(RNAi) animals (see Fig. S4 in the supplementary material) indicates a persisting tip cell function, which might reflect the anchoring of tubule ends to the muscular layer via the prominent flame cell filopodia that are visible in electron micrographs (McKanna, 1968a;Ishii, 1980a).…”

Section: Research Articlementioning

confidence: 99%

“…The suggested loose organization is consistent with the almost instantaneous dissociation of the planarian mesenchyme upon removal of the epithelium (not shown). Readily identifiable ciliation and other criteria previously established in chemically fixed material (McKanna, 1968b;McKanna, 1968a;Ishii, 1980b;Ishii, 1980a) provided a set of morphological features for the identification of protonephridial structures. Flame cells were defined by the 'filtration weir', which consists of closely apposed strands of cytoplasm surrounding a central cilia bundle, and by numerous microvilli between weir and cilia ( Fig.…”

Section: Research Articlementioning

confidence: 99%

“…However, substantial disagreements in the underlying light microscopic observations from the late 19th and early 20th century reveal considerable uncertainty regarding this view (Chichkoff, 1892;Wilhelmi, 1906). On the ultrastructural level, electron microscopy studies described protonephridia as having the following components: (1) cylindrical cells located at the tip of the ciliated side branches, with narrowly apposed strands of cytoplasm forming a fenestrated barrel around a central bundle of cilia, the flickering movements of which gave rise to the term 'flame cell' (McKanna, 1968a;Ishii, 1980a); (2) an initial ciliated tubule segment connected to the lumen of the flame cell barrel and purportedly composed of squamous epithelial cells; and (3) nonciliated 'main tubules' composed of a cuboidal epithelium (Pedersen, 1961;McKanna, 1968b;Ishii, 1980b).…”

Section: Introductionmentioning

confidence: 99%

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The maintenance and regeneration of the planarian excretory system are regulated by EGFR signaling

2011

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SUMMARYThe maintenance of organs and their regeneration in case of injury are crucial to the survival of all animals. High rates of tissue turnover and nearly unlimited regenerative capabilities make planarian flatworms an ideal system with which to investigate these important processes, yet little is known about the cell biology and anatomy of their organs. Here we focus on the planarian excretory system, which consists of internal protonephridial tubules. We find that these assemble into complex branching patterns with a stereotyped succession of cell types along their length. Organ regeneration is likely to originate from a precursor structure arising in the blastema, which undergoes extensive branching morphogenesis. In an RNAi screen of signaling molecules, we identified an EGF receptor (Smed-EGFR-5) as a crucial regulator of branching morphogenesis and maintenance. Overall, our characterization of the planarian protonephridial system establishes a new paradigm for regenerative organogenesis and provides a platform for exploring its functional and evolutionary homologies with vertebrate excretory systems.

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“…We here hypothesize a single meandering filtration cleft in the ground pattern of Gastrotricha. Such meandering clefts formed by interdigitated cytoplasmic processes of the terminal organ have a wide distribution among different phyla of the Bilateria [e.g., Plathelminthes (Ishii, 1980;Rhode and Watson, 1994), Kamptozoa (Kü mmel, 1962;Franke, 1993) Priapulida (Kü mmel, 1964)]. A recent study on the protonephridial system of different species of the Loricifera (Neuhaus and Kristensen, in press) may provide another taxon with meandering filtration clefts.…”

Section: Gastrotricha and The Stem Species Of Bilateriamentioning

confidence: 94%

Ultrastructure of the protonephridial system in Neodasys chaetonotoideus (Gastrotricha: Chaetonotida) and in the ground pattern of Gastrotricha

Kieneke

Arbizu

Ahlrichs

2007

Journal of Morphology

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The taxon Neodasys has a basal position within Gastrotricha. This makes it very interesting for phylogenetic considerations in this group. To complete the reconstruction of the nephridial system in the stem species of Gastrotricha started earlier, we have studied the whole protonephridial system of Neodasys chaetonotoideus by means of complete sets of ultrathin sections and TEM. In many characters, protonephridia of N. chaetonotoideus resemble those of macrodasyidan gastrotrich species. For example, each of the six protonephridia, arranged in three pairs, consists of three distinct cells that constitute the continuous protonephridial lumen. Especially, the terminal cell of the protonephridia of N. chaetonotoideus shows a striking pattern: The perforation of the filter region is a meandering cleft that is continuous with the seam of the enfolded lumen of that cell. With the results presented here and that of former TEM studies, we give a comprehensive idea of the excretory organs in the ground pattern of Gastrotricha. Moreover, we can elaborate on the hypothesized protonephridial system in the stem species of Bilateria. We suggest that a meandering filtration cleft is a feature of the ground pattern of the Bilateria.

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The ultrastructure of the protonephridial flame cell of the freshwater planarian Bdellocephala brunnea

Cited by 12 publications

References 0 publications

Morphology of the Turbellaria at the ultrastructural level

Morphology of the Turbellaria at the ultrastructural level

The maintenance and regeneration of the planarian excretory system are regulated by EGFR signaling

Ultrastructure of the protonephridial system in Neodasys chaetonotoideus (Gastrotricha: Chaetonotida) and in the ground pattern of Gastrotricha

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