Development of the excretory system in the polyplacophoran mollusc,<i>Lepidochitona corrugata</i>: The protonephridium

Baeumler, Natalie; Haszprunar, Gerhard; Ruthensteiner, Bernhard

doi:10.1002/jmor.10964

Cited by 12 publications

(12 citation statements)

References 37 publications

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“…The (developing) metanephridial system resembles the protonephridia [14] of Lepidochitona corrugata in several aspects: (1) Both organ systems start most internally with ultrafiltration sites. These are followed by a transportation duct, then a modification portion, and finally an efferent duct, which opens via a pore to the outside.…”

Section: Discussionmentioning

confidence: 99%

“…However, the overall data are still fragmentary and do not permit a final clarification of that question. For example, it remains unclear if the absorptive portions (kidneys) of protonephridia are homologous throughout the Mollusca [14]. …”

Section: Discussionmentioning

confidence: 99%

“…Entoprocta, Mollusca, Sipuncula, and Annelida; doubtfully also Nemertinea) [4,5,9,47] and thus plesiomorphic for the Mollusca (see also [14]).…”

Section: Discussionmentioning

confidence: 99%

“…During the course of development, molluscs typically exhibit both types of excretory systems, protonephridia and a metanephridial system (Figure 1 of [14]). Polyplacophorans have always played a central role in considerations on molluscan phylogeny.…”

Section: Introductionmentioning

confidence: 99%

“…New data on metanephridial system formation in Polyplacophorans are required, since previous studies were carried out with inadequate methods [17] or are incomplete [13]. In a previous study we have investigated differentiation and organization of the protonephridia of the polyplacophoran Lepidochitona corrugata [14]. In this study we continue with the metanephridial system of this species.…”

Section: Introductionmentioning

confidence: 99%

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Development of the excretory system in a polyplacophoran mollusc: stages in metanephridial system development

2012

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BackgroundTwo types of excretory systems, protonephridia and metanephridial systems are common among bilaterians. The homology of protonephridia of lophotrochozoan taxa has been widely accepted. In contrast, the homology of metanephridial systems – including coelomic cavities as functional units – among taxa as well as the homology between the two excretory systems is a matter of ongoing discussion. This particularly concerns the molluscan kidneys, which are mostly regarded as being derived convergently to the metanephridia of e.g. annelids because of different ontogenetic origin. A reinvestigation of nephrogenesis in polyplacophorans, which carry many primitive traits within molluscs, could shed light on these questions.ResultsThe metanephridial system of Lepidochitona corrugata develops rapidly in the early juvenile phase. It is formed from a coelomic anlage that soon achieves endothelial organization. The pericardium and heart are formed from the central portion of the anlage. The nephridial components are formed by outgrowth from lateral differentiations of the anlage. Simultaneously with formation of the heart, podocytes appear in the atrial wall of the pericardium. In addition, renopericardial ducts, kidneys and efferent nephroducts, all showing downstream ciliation towards the internal lumen, become differentiated (specimen length: 0.62 mm). Further development consists of elongation of the kidney and reinforcement of filtration and reabsorptive structures.ConclusionsDuring development and in fully formed condition the metanephridial system of Lepidochitona corrugata shares many detailed traits (cellular and overall organization) with the protonephridia of the same species. Accordingly, we suggest a serial homology of various cell types and between the two excretory systems and the organs as a whole. The formation of the metanephridial system varies significantly within Mollusca, thus the mode of formation cannot be used as a homology criterion. Because of similarities in overall organization, we conclude that the molluscan metanephridial system is homologous with that of the annelids not only at the cellular but also at the organ level.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…Entoprocta, Mollusca, Sipuncula, and Annelida; doubtfully also Nemertinea) [4,5,9,47] and thus plesiomorphic for the Mollusca (see also [14]).…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Development of the excretory system in a polyplacophoran mollusc: stages in metanephridial system development

2012

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Euopisthobranchs: Excretory System

Bartolomaeus,

Malaquias,

Lobo‐da‐Cunha

2023

Microscopic Anatomy of Animals

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As in other gastropods, in euopisthobranchs the pericardial cavity that surrounds the heart is spatially and functionally connected to the excretory system, forming the renopericardial system. Podocytes or podocyte‐like cells of the auricular epicardium and pericardium wall mediate selective fluid transfer from the circulatory system into the pericardium. Therefore, the fluid inside the pericardium is primary urine. Functionally and structurally, the renopericardial consists of three sections, i.e. (i) podocytes of the atrial and pericardial wall serve in ultrafiltration, (ii) a ciliated renopericardial duct transports the ultrafiltrate into the kidney, and (iii) and unciliated kidney that modifies the ultrafiltrate. The kidney cells are highly vesiculated, unciliated cells with basal infolds indicative for transcytosis across the epithelium. In small euopisthobranch species, the kidney is basically a simple duct, in larger species, like in those of the genus Aplysia , the kidney consists of large, branched, anatomizing, and intertwined ducts. The modified primary urine is released to the exterior via a short ciliated duct that terminates in the nephropore.

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The other gastropod larvae: Larval morphogenesis in a marine neritimorph

Page

Ferguson

2012

Journal of Morphology

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Two of the three major gastropod clades with feeding larvae are sister groups and larval morphogenesis for members of these clades, the Caenogastropoda and Heterobranchia, has been well studied. The third clade, the Neritimorpha, has an unstable phylogenetic position and little is known about development of their planktotrophic larvae. Information about larval morphology of neritimorphs and resolution of their controversial phylogenetic placement is critically important for understanding evolution of larval feeding within the Gastropoda. We describe larval morphogenesis to metamorphic competence for laboratory-reared larvae of Nerita melanotragus (Smith, 1884) (Neritimorpha: Neritidae). Preliminary observations suggest that prehatch larvae are capable of delayed hatching, possibly by entering a diapause state. Our description of larval morphogenesis, as based on tissue sections for light and transmission electron microscopy, scanning electron microscopy, three-dimensional-reconstructions of sectioned tissue, and labeling of muscles with fluorphore-tagged phalloidin, revealed four features that are unprecedented among both feeding and nonfeeding gastropod larvae. Larvae of N. melanotragus have muscles on the left and right side that both meet current criteria of a larval retractor muscle; shell-anchored muscles with oblique striations that project inside the visceral nerve loop to insert mainly on the velar lobes. They also have left and right digestive glands of similar size and a left and right hypobranchial gland. A larval "heart" is absent, but water circulation through the mantle cavity may be facilitated by large circular orifices, lined by patches of motile cilia, leading in and out of the mantle cavity. Comparison of larval traits among all three groups of gastropods with feeding larvae indicates that larvae of N. melanotragus have many unique characteristics, but they show more similarities to caenogastropod than to heterobranch larvae. These results are a significant step toward the goal of identifying primitive versus derived larval traits among feeding gastropod larvae.

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Development of the excretory system in the polyplacophoran mollusc,Lepidochitona corrugata: The protonephridium

Cited by 12 publications

References 37 publications

Development of the excretory system in a polyplacophoran mollusc: stages in metanephridial system development

Development of the excretory system in a polyplacophoran mollusc: stages in metanephridial system development

Euopisthobranchs: Excretory System

The other gastropod larvae: Larval morphogenesis in a marine neritimorph

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