Entwicklungsgeschichtliche Studien an Paludicolen Tricladen

Seilern-Aspang, F.

doi:10.1007/bf01342567

Cited by 28 publications

(11 citation statements)

References 7 publications

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“…1f). Fusiform yolk cells are distributed throughout the egg capsule and are not restricted to the neighborhood of oocytes, as suggested by previous works (Seilern-Aspang 1958;Koscielski 1966). Fusiform yolk cells ultrastructurally show heterochromatin-rich, round nuclei surrounded by a peculiar corona of electrondense, hyaline material (Fig.…”

Section: Yolk Cells and Syncytium Formationmentioning

confidence: 60%

“…At an early stage, a subset of blastomeres assembles and differentiates into a motile, yolk-feeding organism that resembles in many respects a larval form. The early planarian embryo was indeed called 'larva' by previous authors (Fulinski 1916;Seilern-Aspang 1958;Koscielski 1966); we will use the term "cryptic larva" in the following. The cryptic larva possesses a complete epidermis, a pharynx, and a number of neuron-like cells; it moves freely within the egg capsule and pumps the non-fused, spherical yolk cells into its interior which thereby develops into the gastric cavity.…”

Section: Introductionmentioning

confidence: 98%

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Early embryogenesis of planaria: a cryptic larva feeding on maternal resources

2006

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The early planarian embryo presents a complete ciliated epidermis and a pharynx and feeds on maternal yolk cells. In this paper, we report on all the elements involved in the formation of such an autonomous embryo, which we name cryptic larva. First, we provide a description of the spherical and fusiform yolk cells and their relationship with the blastomeres, from the laying of the egg capsule up to their final fate in mid embryonic stages. Then, we describe the early cleavage and the subsequent development of the tissues of the cryptic larva, namely, the primary epidermis, the embryonic pharynx, and a new cell type, the star cells. Finally, we discuss the possibility that the cryptic larva either constitutes a vestigial larva or, more likely, is the evolutionary result of the competition between multiple embryos for the limited and shared maternal resources in the egg capsule.

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Section: Yolk Cells and Syncytium Formationmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 98%

Early embryogenesis of planaria: a cryptic larva feeding on maternal resources

2006

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“…These aberrant forms might rather be the result of twin embryos (Fig. 2a) that have grown together during embryonic development, than adults that were accidentally incised longitudinally (Sekera 1911; Steinmann and Bresslau 1913; Seilern-Aspang 1958). …”

Section: Why Can Some Flatworm Species Regenerate While Others Cannot?mentioning

confidence: 99%

Free-living flatworms under the knife: past and present

2006

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Traditionally, regeneration research has been closely tied to flatworm research, as flatworms (Plathelminthes) were among the first animals where the phenomenon of regeneration was discovered. Since then, the main focus of flatworm regeneration research was on triclads, for which various phenomena were observed and a number of theories developed. However, free-living flatworms encompass a number of other taxa where regeneration was found to be possible. This review aims to display and to compare regeneration in all major free-living flatworm taxa, with special focus on a new player in the field of regeneration, Macrostomum lignano (Macrostomorpha). Findings on the regeneration capacity of this organism provide clues for links between regeneration and (post-)embryonic development, starvation, and asexual reproduction. The role of the nervous system and especially the brain for regeneration is discussed, and similarities as well as particularities in regeneration among free-living flatworms are pointed out.

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“…Microarray analysis reveals quite different profiles of human glioma cell lines grown in leg vs. brain [361]. Moreover, tumors grow on posterior regions of Triturus less readily than they do on anterior regions [362], and numerous such differences are observed in human tumors as well [363–368]. These studies suggest a link between large-scale axial patterning in adult organisms and the potential for failed perception of morphogenetic cues by cells.…”

Section: Introductionmentioning

confidence: 99%

Endogenous Voltage Potentials and the Microenvironment: Bioelectric Signals that Reveal, Induce and Normalize Cancer

Chernet¹,

Levin²

2014

J Clin Exp Oncol

137

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Cancer may be a disease of geometry: a misregulation of the field of information that orchestrates individual cells’ activities towards normal anatomy. Recent work identified molecular mechanisms underlying a novel system of developmental control: bioelectric gradients. Endogenous spatio-temporal differences in resting potential of non-neural cells provide instructive cues for cell regulation and complex patterning during embryogenesis and regeneration. It is now appreciated that these cues are an important layer of the dysregulation of cell: cell interactions that leads to cancer. Abnormal depolarization of resting potential (Vmem) is a convenient marker for neoplasia and activates a metastatic phenotype in genetically-normal cells in vivo. Moreover, oncogene expression depolarizes cells that form tumor-like structures, but is unable to form tumors if this depolarization is artificially prevented by misexpression of hyperpolarizing ion channels. Vmem triggers metastatic behaviors at considerable distance, mediated by transcriptional and epigenetic effects of electrically-modulated flows of serotonin and butyrate. While in vivo data on voltages in carcinogenesis comes mainly from the amphibian model, unbiased genetic screens and network profiling in rodents and human tissues reveal several ion channel proteins as bona fide oncogene and promising targets for cancer drug development. However, we propose that a focus on specific channel genes is just the tip of the iceberg. Bioelectric state is determined by post-translational gating of ion channels, not only from genetically-specified complements of ion translocators. A better model is a statistical dynamics view of spatial Vmem gradients. Cancer may not originate at the single cell level, since gap junctional coupling results in multi-cellular physiological networks with multiple stable attractors in bioelectrical state space. New medical applications await a detailed understanding of the mechanisms by which organ target morphology stored in real-time patterns of ion flows is perceived or mis-perceived by cells. Mastery of somatic voltage gradients will lead to cancer normalization or rebooting strategies, such as those that occur in regenerating and embryonic organs, resulting in transformative advances in basic biology and oncology.

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Entwicklungsgeschichtliche Studien an Paludicolen Tricladen

Cited by 28 publications

References 7 publications

Early embryogenesis of planaria: a cryptic larva feeding on maternal resources

Early embryogenesis of planaria: a cryptic larva feeding on maternal resources

Free-living flatworms under the knife: past and present

Endogenous Voltage Potentials and the Microenvironment: Bioelectric Signals that Reveal, Induce and Normalize Cancer

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