The formation of the gonadal ridge in Xenopus laevis

Development ◽  
1976 ◽  
Vol 35 (1) ◽  
pp. 149-157
Author(s):  
C. C. Wylie ◽  
T. B. Roos
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Time Lapse ◽  
Active Movement ◽  
Surface Phenomena ◽  
Cytoplasmic Processes

Previous studies have described the morphology, including the ultrastructure, of primordial germ cells (PGCs), and the cells with which they associate to form the gonadal ridge, in Xenopus laevis. In order to test their capacity for active movement we have studied single, isolated PGCs in vitro. Time-lapse studies of these cells reveal that they are motile, using broad cytoplasmic processes. The fact that these cells are very large and easy to manipulate in vitro makes them an attractive subject of study, particularly with respect to the mechanism of their movement and the surface phenomena which guide them to the site of the gonadal ridge.

Electron microscopic studies on the structure of motile primordial germ cells of Xenopus laevis in vitro

Development ◽  
1978 ◽  
Vol 46 (1) ◽  
pp. 119-133
Author(s):  
Janet Heasman ◽  
C. C. Wylie
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Structural Features ◽  
Culture Conditions ◽  
Structural Basis ◽  
Electron Microscopic ◽  
Microscopic Studies

Primordial germ cells (PGCs) of Xenopus laevis have been isolated from early embryos and kept alive in vitro, in order to study the structural basis of their motility, using the transmission and scanning electron microscope. The culture conditions used mimicked as closely as possible the in vivo environment of migrating PGCs, in that isolated PGCs were seeded onto monolayers of amphibian mesentery cells. In these conditions we have demonstrated that: (a) No significant differences were found between the morphology of PGCs in vitro and in vivo. (b) Structural features involved in PGC movement in vitro include (i) the presence of a filamentous substructure, (ii) filopodial and blunt cell processes, (iii) cell surface specializations. These features are also characteristic of migratory PGCs studied in vivo. (c) PGCs in vitro have powers of invasion similar to those of migrating PGCs in vivo. They occasionally become completely surrounded by cells of the monolayer and, in this situation, bear striking resemblance to PGCs moving between mesentery cells to the site of the developing gonad in stage-44 tadpoles. We conclude that as far as it is possible to assess, the behaviour of isolated PGCs in these in vitro conditions mimics their activities in vivo. This allows us to study the ultrastructural basis of their migration.

The migration of presumptive primordial germ cells through the endodermal cell mass in Xenopus laevis: A light and electron microscopic study

Development ◽  
1980 ◽  
Vol 59 (1) ◽  
pp. 1-17
Author(s):  
Michiko Kamimura ◽  
Minoru Kotani ◽  
Kenzo Yamagata
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Intercellular Space ◽  
Primordial Germ Cells ◽  
Cell Mass ◽  
Light And Electron Microscopy ◽  
Morphological Characteristics ◽  
Light Microscope Level ◽  
Cytoplasmic Processes ◽  
Germinal Plasm

Presumptive primordial germ cells (pPGCs) were examined during migration from their deep endodermal position to the endodermal crest in Xenopus laevis, using light and electron microscopy with Epon sections, and several morphological characteristics of pPGCs, associated with their migration, were revealed. pPGCs displayed polymorphism, with smooth contours. The intercellular space around the pPGCs was large and variable in width and cytoplasmic processes from pPGCs were occasionally observed in it. It was shown quantitatively that pPGCs at the migratory stage had a tendency to move with the leading end, towards which the nucleus was localized, dragging the germinal plasm behind. These polarized pPGCs were frequently associated with large intercellular spaces, both at their leading and trailing ends. Cytoplasmic processes of polarizing pPGCs found in the large intercellular space at the leading end were conspicuous. Ultrastructurally, the nuclei of pPGCs were euchromatic, and the nucleolus was prominent. The germinal plasm at the light microscope level corresponded to the cytoplasmic area near the nucleus where a large number of mitochondria with well-developed cristae and most of the other organelles were aggregated. Centrioles and centriole-associated microtubules observed in the aggregate were thought to be important structures responsible for the cell polarization mentioned above. It was demonstrated quantitatively that the size of mitochondria in pPGCs was larger on average than that of mitochondria in neighbouring somatic endodermal cells. Numerous irregularly shaped small yolk platelets characterized pPGCs. These ultrastructural features suggested that pPGCs were in an activated metabolic state. It was concluded that the migration of pPGCs was attributable to active movement with high cell metabolism, causing the formation of cell processes and intracellular polarization.

scholarly journals Migratory and adhesive properties of Xenopus laevis primordial germ cells in vitro

Biology Open ◽  
2013 ◽  
Vol 2 (12) ◽  
pp. 1279-1287 ◽  
Author(s):  
A. Dzementsei ◽  
D. Schneider ◽  
A. Janshoff ◽  
T. Pieler
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Adhesive Properties

scholarly journals Invasive behaviour of mouse primordial germ cells in vitro

1986 ◽  
Vol 86 (1) ◽  
pp. 133-144
Author(s):  
D. Stott ◽  
C.C. Wylie
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Time Lapse ◽  
Cell Types ◽  
Fluorescent Labelling ◽  
Mouse Embryo Fibroblast ◽  
Substrate Interaction ◽  
Close Contacts

We have isolated migrating primordial germ cells (PGCs) from 10.5-day mouse embryos and studied their behaviour when cultured on a mouse embryo fibroblast (STO) cell line. Living and fixed PGCs were identified by fluorescent labelling with a monoclonal antibody specific for PGCs in the culture system used. The behaviour of the cells was studied using interference reflexion microscopy (IRM) and time-lapse video cinematography. The IRM pattern displayed by PGCs is typical of highly motile cell types, the cells lack focal contacts and possess large areas of close contacts indicative of weak membrane to substrate interaction. The PGCs exhibit relatively high rates of translocation and lack contact inhibition. They were observed to underlap STO cells in subconfluent monolayers and to penetrate between the cells of confluent monolayers, becoming located between the monolayer and its substrate. These observations support the hypothesis that migrating mouse PGCs are inherently motile and are able transiently to disrupt the adhesion of surrounding cells. These results suggest that PGCs actively migrate to the developing gonad in vivo.

Studies on the locomotion of primordial germ cells from Xenopus laevis in vitro

Development ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 149-161
Author(s):  
Janet Heasman ◽  
Tim Mohun ◽  
C. C. Wylie
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Cell Movement ◽  
Embryonic Cell ◽  
Artificial Substrates ◽  
Embryonic Cells ◽  
Adult Kidney

The mechanism of embryonic cell movement is poorly understood. Primordial germ cells (PGCs) of the anuran amphibian Xenopus laevis migrate individually from their site of determination in the embryonic endoderm to their site of differentiation, in the developing gonad. PGCs have been isolated during their migratory phase from tadpoles, and their movement studied in vitro on a variety of natural and artificial substrates. On all artificial substrates used, including acid-washed glass, tissue-culture plastics, poly-L-Iysine-coated glass, and collagen, the PGCs move by amoeboid extrusion of hemispherical lobopodia. Several considerations make it unlikely that this is the mechanism employed in vivo. On living cellular substrates, e.g. monolayers of Xenopus laevis embryonic cells, adult kidney cells, and adult mesentery cells, PGCs become firmly attached and undergo phases of elongation and contraction. They move by elongation, coupled with the extrusion of filopodia, followed by waves of contraction, and ultimately by retraction of the trailing end of the cell. Evidence is presented that this is the mode of locomotion normally employed by PGCs in vivo.

scholarly journals Formative pluripotent stem cells show features of epiblast cells poised for gastrulation

Cell Research ◽  
2021 ◽  
Author(s):  
Xiaoxiao Wang ◽  
Yunlong Xiang ◽  
Yang Yu ◽  
Ran Wang ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Germ Cells ◽  
Pluripotent Stem Cells ◽  
Primordial Germ Cells ◽  
Embryonic Stem ◽  
Large Set ◽  
Mouse Escs ◽  
Epiblast Stem Cells ◽  
Early Gastrula

AbstractThe pluripotency of mammalian early and late epiblast could be recapitulated by naïve embryonic stem cells (ESCs) and primed epiblast stem cells (EpiSCs), respectively. However, these two states of pluripotency may not be sufficient to reflect the full complexity and developmental potency of the epiblast during mammalian early development. Here we report the establishment of self-renewing formative pluripotent stem cells (fPSCs) which manifest features of epiblast cells poised for gastrulation. fPSCs can be established from different mouse ESCs, pre-/early-gastrula epiblasts and induced PSCs. Similar to pre-/early-gastrula epiblasts, fPSCs show the transcriptomic features of formative pluripotency, which are distinct from naïve ESCs and primed EpiSCs. fPSCs show the unique epigenetic states of E6.5 epiblast, including the super-bivalency of a large set of developmental genes. Just like epiblast cells immediately before gastrulation, fPSCs can efficiently differentiate into three germ layers and primordial germ cells (PGCs) in vitro. Thus, fPSCs highlight the feasibility of using PSCs to explore the development of mammalian epiblast.

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