The use of ‘normal’ and ‘transformed’ gynandromorphs in mapping the primordial germ cells and the gonadal mesoderm in Drosophila

Development ◽  
1976 ◽  
Vol 35 (3) ◽  
pp. 607-616
Author(s):  
W. J. Gehring ◽  
E. Wieschaus ◽  
M. Holliger
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Ventral Side ◽  
Drosophila Embryo ◽  
The Real ◽  
Genital Disc ◽  
Stage Of Development ◽  
Data Support ◽  
Blastoderm Stage

The primordial germ cells and the gonadal mesoderm were mapped in the Drosophila embryo by analyzing the patterns of mosaicism in ‘normal’ and ‘transformed’ gynandromorphs. Relative to the adult cuticular markers the germ cells map as the posterior moststructure, which coincides with their known location in the blastoderm embryo. These data support the hypothesis that the gynandromorph map reflects the real position of the pri-mordia in the embryo. Since after the blastoderm stage the primordial germ cells migrateanteriorly these data also indicate that the map in fact corresponds to the blastoderm stageand not to a later stage of development. The genital disc maps as a single median primordium anterior and ventral to the germ cells, the gonadal mesoderm is located anterior to the genital disc and also forms a single median primordium on the ventral side of the embryo. The primordia for the genital disc and the gonadal mesoderm are unusually large in size, which presumably reflects some indeterminacy of the cell lineage leading to an ‘expansion’ of the map.

Dual role of Ovol2 on the germ cell lineage segregation during gastrulation in mouse embryogenesis

Development ◽  
2022 ◽  
Author(s):  
Yuki Naitou ◽  
Go Nagamatsu ◽  
Nobuhiko Hamazaki ◽  
Kenjiro Shirane ◽  
Masafumi Hayashi ◽  
...  
Keyword(s):  
Germ Cells ◽  
Splice Variant ◽  
Epithelial To Mesenchymal Transition ◽  
Functional Relationship ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Animal Kingdom ◽  
Mesenchymal Transition

In mammals, primordial germ cells (PGCs), the origin of the germ line, are specified from the epiblast at the posterior region where gastrulation simultaneously occurs, yet the functional relationship between PGC specification and gastrulation remains unclear. Here, we show that Ovol2, a transcription factor conserved across the animal kingdom, balances these major developmental processes by repressing the epithelial-to-mesenchymal transition (EMT) driving gastrulation and the upregulation of genes associated with PGC specification. Ovol2a, a splice variant encoding a repressor domain, directly regulates EMT-related genes and consequently induces re-acquisition of potential pluripotency during PGC specification, whereas Ovol2b, another splice variant missing the repressor domain, directly upregulates genes associated with PGC specification. Taken together, these results elucidate the molecular mechanism underlying allocation of the germ line among epiblast cells differentiating into somatic cells through gastrulation.

scholarly journals Ligand–Receptor Interactions Elucidate Sex-Specific Pathways in the Trajectory From Primordial Germ Cells to Gonia During Human Development

2021 ◽  
Vol 9 ◽  
Author(s):  
Arend W. Overeem ◽  
Yolanda W. Chang ◽  
Jeroen Spruit ◽  
Celine M. Roelse ◽  
Susana M. Chuva De Sousa Lopes
Keyword(s):  
Germ Cell ◽  
Signaling Pathways ◽  
Germ Cells ◽  
Tyrosine Kinases ◽  
Intracellular Localization ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Systematic Analysis ◽  
Receptor Interactions

The human germ cell lineage originates from primordial germ cells (PGCs), which are specified at approximately the third week of development. Our understanding of the signaling pathways that control this event has significantly increased in recent years and that has enabled the generation of PGC-like cells (PGCLCs) from pluripotent stem cells in vitro. However, the signaling pathways that drive the transition of PGCs into gonia (prospermatogonia in males or premeiotic oogonia in females) remain unclear, and we are presently unable to mimic this step in vitro in the absence of gonadal tissue. Therefore, we have analyzed single-cell transcriptomics data of human fetal gonads to map the molecular interactions during the sex-specific transition from PGCs to gonia. The CellPhoneDB algorithm was used to identify significant ligand–receptor interactions between germ cells and their sex-specific neighboring gonadal somatic cells, focusing on four major signaling pathways WNT, NOTCH, TGFβ/BMP, and receptor tyrosine kinases (RTK). Subsequently, the expression and intracellular localization of key effectors for these pathways were validated in human fetal gonads by immunostaining. This approach provided a systematic analysis of the signaling environment in developing human gonads and revealed sex-specific signaling pathways during human premeiotic germ cell development. This work serves as a foundation to understand the transition from PGCs to premeiotic oogonia or prospermatogonia and identifies sex-specific signaling pathways that are of interest in the step-by-step reconstitution of human gametogenesis in vitro.

Identification of tissues and patterning events required for distinct steps in early migration of zebrafish primordial germ cells

Development ◽  
1999 ◽  
Vol 126 (23) ◽  
pp. 5295-5307 ◽  
Author(s):  
G. Weidinger ◽  
U. Wolke ◽  
M. Koprunner ◽  
M. Klinger ◽  
E. Raz
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Paraxial Mesoderm ◽  
Molecular Characteristics ◽  
Dorsoventral Patterning ◽  
Wild Type ◽  
Migration Process ◽  
Early Migration ◽  
Somatic Tissues

In many organisms, the primordial germ cells have to migrate from the position where they are specified towards the developing gonad where they generate gametes. Extensive studies of the migration of primordial germ cells in Drosophila, mouse, chick and Xenopus have identified somatic tissues important for this process and demonstrated a role for specific molecules in directing the cells towards their target. In zebrafish, a unique situation is found in that the primordial germ cells, as marked by expression of vasa mRNA, are specified in random positions relative to the future embryonic axis. Hence, the migrating cells have to navigate towards their destination from various starting positions that differ among individual embryos. Here, we present a detailed description of the migration of the primordial germ cells during the first 24 hours of wild-type zebrafish embryonic development. We define six distinct steps of migration bringing the primordial germ cells from their random positions before gastrulation to form two cell clusters on either side of the midline by the end of the first day of development. To obtain information on the origin of the positional cues provided to the germ cells by somatic tissues during their migration, we analyzed the migration pattern in mutants, including spadetail, swirl, chordino, floating head, cloche, knypek and no isthmus. In mutants with defects in axial structures, paraxial mesoderm or dorsoventral patterning, we find that certain steps of the migration process are specifically affected. We show that the paraxial mesoderm is important for providing proper anteroposterior information to the migrating primordial germ cells and that these cells can respond to changes in the global dorsoventral coordinates. In certain mutants, we observe accumulation of ectopic cells in different regions of the embryo. These ectopic cells can retain both morphological and molecular characteristics of primordial germ cells, suggesting that, in zebrafish at the early stages tested, the vasa-expressing cells are committed to the germ cell lineage.

140 LOCALIZATION OF PRIMORDIAL GERM CELLS IN DAY 21 BOVINE EMBRYOS

2007 ◽  
Vol 19 (1) ◽  
pp. 188
Author(s):  
N. I. Alexopoulos ◽  
N. T. D'Cruz ◽  
P. Maddox-Hyttel
Keyword(s):  
Neural Tube ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Yolk Sac ◽  
Bovine Embryos ◽  
Surface Ectoderm ◽  
Oct4 Expression ◽  
Visceral Mesoderm ◽  
Stage Of Development

In most animal species, germ cell precursors, i.e., primordial germ cells (PGCs), arise from the epiblast and then migrate to the future gonadal ridge during development. At least in the mouse, PGCs may be cultured as embryonic germ cells that remain pluripotent. PGCs are the only cells in which OCT4 expression is maintained after gastrulation. The present study aimed at identifying the localization of PGCs in Day 21 in vivo-derived bovine embryos by immunohistochemical staining against OCT4. Six embryos were obtained after slaughter of superovulated heifers 21 days after insemination. The uterine tracts were flushed and embryos fixed, paraffin-embedded, and processed for immunohistochemistry. Embryos were sagitally sectioned, and selected serial sections were immunohistochemically stained for OCT4 to identify potential PGCs. Two embryos were at the neural groove stage. At this stage of development, the primitive gut had not yet been abstricted from the yolk sac and the allantois was not visible. A weak homogeneous OCT4 staining was localized to nuclei in a well-defined region of the epiblast, which was in the process of a gradual anterior to posterior differentiation into neural and surface ectoderm. Moreover, a strong OCT4 staining was localized to a few scattered cells found in the visceral mesoderm associated with the yolk sac in the region of the endoderm-hypoblast transition at some distance from the embryo proper. Four embryos were at the neural tube/somite stage. At this stage of development, the primitive gut had been defined and only the midgut was connected to the yolk sac. Furthermore, the allantois was visible as an anchor-shaped structure at the posterior end of the embryo. A strong OCT4 staining was found in nuclei of solitary cells in the endoderm and its associated visceral mesoderm of the ventral aspect of the mid and hindgut. The described OCT4 staining corresponds well with previous findings in the pig, in which presumptive PGCs are found in the endoderm epithelium during the neural groove stage. Later, during the early somite stages, they are localized in the endoderm and visceral mesoderm of the yolk sac and allantois, and in later somite stages, they are found in the developing genital ridge. This is, however, the first study to demonstrate the localization of these cells, at least by OCT4 staining, in bovine embryos at the neural groove and neural tube/somite stages.

scholarly journals Purification of mouse primordial germ cells by Nycodenz

Reproduction ◽  
2003 ◽  
pp. 667-675 ◽  
Author(s):  
T Mayanagi ◽  
R Kurosawa ◽  
K Ohnuma ◽  
A Ueyama ◽  
K Ito ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Specific Antibody ◽  
Membrane Surface ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Specific Antigen ◽  
Cell Lineage ◽  
New Method ◽  
Purification Method

Primordial germ cells are important cells for the study of germ cell lineage. It has proved difficult to obtain highly purified primordial germ cells for preparation of a specific antibody. In the present study, a new method for purifying mouse primordial germ cells was developed using a Nycodenz gradient. Furthermore, the polyclonal anti-mouse primordial germ cells IgG derived from mouse primordial germ cells was prepared. As this IgG reacted only with primordial germ cells obtained at day 12.5 after mating, this antibody appeared to recognize the stage-specific antigen of primordial germ cells. One reason that a continuous primordial germ cell marker has not been obtained is because the purity of the primordial germ cells used has been too low to prepare the antibody. This new method represents a significant improvement in the purification of primordial germ cells; it is simpler than previous methods, and produced mouse primordial germ cells with a purity of more than 95%. In addition, the separation reagent Nycodenz is non-toxic and achieved separation of primordial germ cells without attachment of antibodies against the primordial germ cell membrane surface. This new purification method and stage-specific antibody will be useful for the analysis of the mechanisms of primordial germ cell migration.

scholarly journals Bayesian inference of transcriptional branching identifies regulators of early germ cell development in humans

2017 ◽  
Author(s):  
Christopher A. Penfold ◽  
Anastasiya Sybirna ◽  
John Reid ◽  
Aracely Castillo Venzor ◽  
Elena Drousioti ◽  
...  
Keyword(s):  
Cell Fate ◽  
Germ Cells ◽  
Temporal Dynamics ◽  
Primordial Germ Cells ◽  
Series Data ◽  
Human Embryos ◽  
Marker Genes ◽  
Cell Fate Decisions ◽  
Stage Of Development

AbstractDuring embryonic development, cells undertake a series of fate decisions to form a complete organism comprised of various cell types, epitomising a branching process. A striking example of branching occurs in humans around the time of implantation, when primordial germ cells (PGCs), precursors of sperm and eggs, and somatic lineages are specified. Due to inaccessibility of human embryos at this stage of development, understanding the mechanisms of PGC specification remains difficult. The integrative modelling of single cell transcriptomics data from embryos and appropriate in vitro models should prove to be a useful resource for investigating this system, provided that the cells can be suitably ordered over a developmental axis. Unfortunately, most methods for inferring cell ordering were not designed with structured (time series) data in mind. Although some probabilistic approaches address these limitations by incorporating prior information about the developmental stage (capture time) of the cell, they do not allow the ordering of cells over processes with more than one terminal cell fate. To investigate the mechanisms of PGC specification, we develop a probabilistic pseudotime approach, branch-recombinant Gaussian process latent variable models (B-RGPLVMs), that use an explicit model of transcriptional branching in individual marker genes, allowing the ordering of cells over developmental trajectories with arbitrary numbers of branches. We use first demonstrate the advantage of our approach over existing pseudotime algorithms and subsequently use it to investigate early human development, as primordial germ cells (PGCs) and somatic cells diverge. We identify known master regulators of human PGCs, and predict roles for a variety of signalling pathways, transcription factors, and epigenetic modifiers. By concentrating on the earliest branched signalling events, we identified an antagonistic role for FGF receptor (FGFR) signalling pathway in the acquisition of competence for human PGC fate, and identify putative roles for PRC1 and PRC2 in PGC specification. We experimentally validate our predictions using pharmacological blocking of FGFR or its downstream effectors (MEK, PI3K and JAK), and demonstrate enhanced competency for PGC fate in vitro, whilst small molecule inhibition of the enzymatic component of PRC1/PRC2 reveals reduced capacity of cells to form PGCs in vitro. Thus, B-RGPLVMs represent a powerful and flexible data-driven approach for dissecting the temporal dynamics of cell fate decisions, providing unique insights into the mechanisms of early embryogenesis. Scripts relating to this analysis are available from: https://github.com/cap76/PGCPseudotime

scholarly journals Functional reconstruction of NANOS3 expression in the germ cell lineage by a novel transgenic reporter reveals distinct subcellular localizations of NANOS3

Reproduction ◽  
2010 ◽  
Vol 139 (2) ◽  
pp. 381-393 ◽  
Author(s):  
Masashi Yamaji ◽  
Takashi Tanaka ◽  
Mayo Shigeta ◽  
Shinichiro Chuma ◽  
Yumiko Saga ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Regulatory Elements ◽  
Initiation Factor ◽  
Processing Bodies

Mutations of RNA-binding proteins such as NANOS3, TIAL1, and DND1 in mice have been known to result in the failure of survival and/or proliferation of primordial germ cells (PGCs) soon after their fate is specified (around embryonic day (E) 8.0), leading to the infertility of these animals. However, the mechanisms of actions of these RNA-binding proteins remain largely unresolved. As a foundation to explore the role of these RNA-binding proteins in germ cells, we established a novel transgenic reporter strain that expresses NANOS3 fused with EGFP under the control of Nanos3 regulatory elements. NANOS3–EGFP exhibited exclusive expression in PGCs as early as E7.25, and continued to be expressed in female germ cells until around E14.5 and in male germ cells throughout the fetal period with declining expression levels after E16.5. NANOS3–EGFP resumed strong expression in postnatal spermatogonia and continued to be expressed in undifferentiated spermatogonial cells in adults. Importantly, the Nanos3–EGFP transgene rescued the sterile phenotype of Nanos3 homozygous mutants, demonstrating the functional equivalency of NANOS3–EGFP with endogenous NANOS3. We found that throughout germ cell development, a predominant amount of  NANOS3–EGFP co-localized with TIAL1 (also known as TIAR) and phosphorylated eukaryotic initiation factor 2α, markers for the stress granules, whereas a fraction of it showed co-localization with DCP1A, a marker for the processing bodies. On the other hand, NANOS3–EGFP did not co-localize with Tudor domain-containing protein 1, a marker for the intermitochondrial cements, in spermatogenic cells. These findings unveil the presence of distinct posttranscriptional regulations in PGCs soon after their specification, for which RNA-binding proteins such as NANOS3 and TIAL1 would play critical functions.

Memoirs: The Origin and Migration of the Primordial Germ-cells of Sphenodon punctatus

1932 ◽  
Vol s2-75 (298) ◽  
pp. 251-282
Author(s):  
MARGARET TRIBE ◽  
F.W. ROGERS BRAMBELL
Keyword(s):  
Germ Cells ◽  
Early Stage ◽  
Venous Blood ◽  
Primordial Germ Cells ◽  
Blood Stream ◽  
Yolk Sac ◽  
Amoeboid Movement ◽  
Stage Of Development ◽  
Sphenodon Punctatus ◽  
And Migration

1. The primordial germ-cells of Sphenodon originate in the yolk-sac endoderm of the area opaca all round the embiyo, but chiefly in a crescentic area in front of it. 2. They differentiate first at a very early stage of development before the differentiation of the medullary plate. 3. The primordial germ-cells are characterized by their very large size, in comparison with all the other embryonal cells, and by their content of small yolk-spherules which are sub-equal in size. 4. The primordial germ-cells migrate through the yolk-sac endoderm and mesoderm, apparently by their own power of amoeboid movement. Many of them enter the blood-islands and the sinus terminalis. 5. The primordial germ-cells enter the embryo either (1) passively in the venous blood-stream, or (2) actively by migration through the extra-embryonal endoderm and splanchnic mesoderm into the lateral walls and the mesentery of the midgut groove. 6. The primordial germ-cells in the circulation reach the neighbourhood of the germinal ridges in the dorsal aorta or its branches. They then penetrate the walls of the vessels and migrate through the intervening tissues, together with those that have reached the base of the mid-gut mesentery by way of the splanchnic mesoderm and the mid-gut wall, to the germinal ridges. 7. Many primordial germ-cells get lost during their migration. This is especially true of those travelling in the blood-stream. Such aberrant primordial germ-cells are found occasionally in almost any part of the embryo,, but occur most often in the head, especially in the region of the fore-brain. They ultimately disappear. 8. The primordial germ-cells enter the forming germinal ridges before the coelomic epithelium covering them has begun to proliferate. 9. The primordial germ-cells, having reached the germinal ridges, lose their characteristic yolk-content and enter on the prophase of the heterotypic division.

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