Memoirs: Studies on the Germ-cell Cycle of Cryptocotyle lingua

1934 ◽  
Vol s2-76 (304) ◽  
pp. 573-614
Author(s):  
RAYMOND MILLARD CABLE
Keyword(s):  
Cell Cycle ◽  
Germ Cell ◽  
Germ Cells ◽  
Alternative Hypothesis ◽  
Primordial Germ Cells ◽  
Body Cavity ◽  
The Body ◽  
Larval Stages ◽  
Nuclear Changes ◽  
New Hosts

The writer's earlier study (Cable, 1931) on the germ-cell cycle in the adult stage of Cryptocotyle lingua is supplemented by an investigation of germinal development in the larval stages occurring in the marine snail, Littorina littorea. The miracidium-mother-sporocyst was not found although very young rediae were abundant in the material studied. The primordial germ-cells of the young redia are observed in an undifferentiated condition in the body-cavity, which is not well defined due to an abundance of connective tissue. After a period of differentiation, including growth, progressive nuclear changes, and condensation of cytoplasm, the germ-cells multiply by equal division, a process which is interpreted as polyembryony. Germinal differentiation exhibits a distinct anterior-posterior gradient. The mature germinal cells give rise directly to cercarial embryos without germ-mass formation and dissociation or any maturation processes. Although germinal lineage may be traced in the redia, it seems to be interrupted in the cercaria, due to delayed segregation of germ-cells. The soma of the redia does not produce germ-cells at any stage. Evidence is afforded by this and other studies that germinal lineage with sudden intercalations of polyembryonic stages (germ-masses) cannot explain the germinal cycle of the trematodes as a group. In an alternative hypothesis, based on the phylogeny of the Digenea, it is suggested that the ancestors of this group became sexually mature in the mollusc and completed the cycle in that host, possibly before the appearance of vertebrates; and that, with the evolution of the trematodes, sexual phenomena have gradually been lost, while accessory stages and new hosts have been included in the life-cycle. Cryptocotyle lingua is assumed to have been modified to an intermediate extent since sexual reproduction, germ-masses, and the maximum number of intercalary stages are lacking in the larval generations.

Studies on the germ cell cycle of the digenetic trematode Parorchis acanthus Nicoll

Parasitology ◽  
1940 ◽  
Vol 32 (4) ◽  
pp. 372-391 ◽  
Author(s):  
Gwendolen Rees
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
First Generation ◽  
Body Cavity ◽  
The Body ◽  
Small Cells ◽  
Digenetic Trematode ◽  
Similar Process ◽  
Larval Stages ◽  
Parorchis Acanthus

1. The anatomy of the adult miracidium of Parorchis acanthus is described.2. Development of the miracidium and of the succeeding larval stages has been followed.3. Cleavage of the fertilized egg gives rise to an ectodermal and a propagatory cell. The former gives rise to the soma, and the latter, after contributing a few small cells to the body of the miracidium, becomes the germ cell.4. This germ cell develops in the same way into the first generation redia while still in the body of the miracidium.5. The fully formed miracidium contains a single fully formed redia when it penetrates the intermediate molluscan host.6. In the intermediate host the miracidium disintegrates and second generation rediae are formed from the germ cells in the body cavity of the parent redia.7. The germ cells in the body cavity of the daughter redia give rise to cercariae by a similar process of embryonic development to that found in preceding generations.8. The germ cells in the cercariae become differentiated into the adult genitalia.9. No evidence has been found to show that rediae or cercariae are derived from cells in the wall of the redia.10. No ovary, maturation process, parthenogenesis, or fertilization takes place in any of the larval stages, but germinal lineage is apparent throughout the life cycle.

scholarly journals Germ cell determination and the developmental origin of germ cell tumors

Development ◽  
2021 ◽  
Vol 148 (8) ◽  
Author(s):  
Peter K. Nicholls ◽  
David C. Page
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Germ Cell Tumors ◽  
Cell Types ◽  
The Body ◽  
Developmental Potential ◽  
Animal Development ◽  
Cell Determination ◽  
Diverse Species

ABSTRACT In each generation, the germline is tasked with producing somatic lineages that form the body, and segregating a population of cells for gametogenesis. During animal development, when do cells of the germline irreversibly commit to producing gametes? Integrating findings from diverse species, we conclude that the final commitment of the germline to gametogenesis – the process of germ cell determination – occurs after primordial germ cells (PGCs) colonize the gonads. Combining this understanding with medical findings, we present a model whereby germ cell tumors arise from cells that failed to undertake germ cell determination, regardless of their having colonized the gonads. We propose that the diversity of cell types present in these tumors reflects the broad developmental potential of migratory PGCs.

scholarly journals Discrete somatic niches coordinate proliferation and migration of primordial germ cells via Wnt signaling

2016 ◽  
Vol 214 (2) ◽  
pp. 215-229 ◽  
Author(s):  
Andrea V. Cantú ◽  
Svetlana Altshuler-Keylin ◽  
Diana J. Laird
Keyword(s):  
Cell Cycle ◽  
Germ Cell ◽  
Wnt Signaling ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Early Embryo ◽  
Cell Pool ◽  
And Migration ◽  
Selective Mechanism ◽  
Proliferation And Migration

Inheritance depends on the expansion of a small number of primordial germ cells (PGCs) in the early embryo. Proliferation of mammalian PGCs is concurrent with their movement through changing microenvironments; however, mechanisms coordinating these conflicting processes remain unclear. Here, we find that PGC proliferation varies by location rather than embryonic age. Ror2 and Wnt5a mutants with mislocalized PGCs corroborate the microenvironmental regulation of the cell cycle, except in the hindgut, where Wnt5a is highly expressed. Molecular and genetic evidence suggests that Wnt5a acts via Ror2 to suppress β-catenin–dependent Wnt signaling in PGCs and limit their proliferation in specific locations, which we validate by overactivating β-catenin in PGCs. Our results suggest that the balance between expansion and movement of migratory PGCs is fine-tuned in different niches by the opposing β-catenin–dependent and Ror2-mediated pathways through Wnt5a. This could serve as a selective mechanism to favor early and efficient migrators with clonal dominance in the ensuing germ cell pool while penalizing stragglers.

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.

scholarly journals Phase Transitioned Nuclear Oskar Promotes Cell Division of Drosophila Primordial Germ Cells

2018 ◽  
Author(s):  
Kathryn E. Kistler ◽  
Tatjana Trcek ◽  
Thomas R. Hurd ◽  
Ruoyu Chen ◽  
Feng-Xia Liang ◽  
...  
Keyword(s):  
Germ Cell ◽  
Cell Fate ◽  
Germ Cells ◽  
Cell Function ◽  
Primordial Germ Cells ◽  
Nuclear Localization Sequence ◽  
Cell Systems ◽  
Germ Granules ◽  
Localization Sequence ◽  
Transcriptional Gene Regulation

ABSTRACTGerm granules are non-membranous ribonucleoprotein granules deemed the hubs for post-transcriptional gene regulation and functionally linked to germ cell fate across species. Little is known about the physical properties of germ granules and how these relate to germ cell function. Here we study two types of germ granules in the Drosophila embryo: cytoplasmic germ granules that instruct primordial germ cells (PGCs) formation and nuclear germ granules within early PGCs with unknown function. We show that cytoplasmic and nuclear germ granules are phase transitioned condensates nucleated by Oskar protein that display liquid as well as hydrogel-like properties. Focusing on nuclear granules, we find that Oskar drives their formation in heterologous cell systems. Multiple, independent Oskar protein domains synergize to promote granule phase separation. Deletion of Oskar’s nuclear localization sequence specifically ablates nuclear granules in cell systems. In the embryo, nuclear germ granules promote germ cell divisions thereby increasing PGC number for the next generation.

scholarly journals Disruption of Tcfap2c in Primordial Germ Cells using Prdm1-Cre Prevents Germ Cell Development

2008 ◽  
Vol 78 (Suppl_1) ◽  
pp. 64-64
Author(s):  
Jillian Guttormsen ◽  
Gerrit J. Bouma ◽  
Frances Bhushan ◽  
Trevor Williams ◽  
Quinton A. Winger
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Cell Development ◽  
Germ Cell Development

scholarly journals Larval form of the genus Thubunaea Seurat, 1914 from the body cavity of an insect, Supella sp., at Meerut (U.P.), India

2011 ◽  
Vol 3 (1) ◽  
pp. 54-57
Author(s):  
H.S. Singh ◽  
Malti Malti ◽  
Anshu Chaudhary
Keyword(s):  
Body Cavity ◽  
The Body ◽  
Present Communication ◽  
Larval Form ◽  
Larval Stages

The present communication deals with a larval nematode belonging to the genus Thubunaea Seurat, 1914, from the body cavity of an insect, Supella sp., at Meerut, U.P. Both encysted and free larval stages were recovered. Morphology of the larvae is described in detail.

scholarly journals Gene pathways and cell cycle-related genes in cultured avian primordial germ cells

2012 ◽  
Vol 91 (12) ◽  
pp. 3167-3177 ◽  
Author(s):  
D. Rengaraj ◽  
B.R. Lee ◽  
J.W. Choi ◽  
S.I. Lee ◽  
H.W. Seo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Germ Cells ◽  
Primordial Germ Cells

scholarly journals Follistatin Regulates Germ Cell Nest Breakdown and Primordial Follicle Formation

Endocrinology ◽  
2010 ◽  
Vol 152 (2) ◽  
pp. 697-706 ◽  
Author(s):  
Fuminori Kimura ◽  
Lara M. Bonomi ◽  
Alan L. Schneyer
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Ovarian Function ◽  
Primordial Follicle ◽  
Biochemical Properties ◽  
The Body ◽  
Protein Isoforms ◽  
Primordial Follicles ◽  
Reduced Rate ◽  
Regulatory Functions

Abstract Follistatin (FST) is an antagonist of activin and related TGFβ superfamily members that has important reproductive actions as well as critical regulatory functions in other tissues and systems. FST is produced as three protein isoforms that differ in their biochemical properties and in their localization within the body. We created FST288-only mice that only express the short FST288 isoform and previously reported that females are subfertile, but have an excess of primordial follicles on postnatal day (PND) 8.5 that undergo accelerated demise in adults. We have now examined germ cell nest breakdown and primordial follicle formation in the critical PND 0.5–8.5 period to test the hypothesis that the excess primordial follicles derive from increased proliferation and decreased apoptosis during germ cell nest breakdown. Using double immunofluorescence microscopy we found that there is virtually no germ cell proliferation after birth in wild-type or FST288-only females. However, the entire process of germ cell nest breakdown was extended in time (through at least PND 8.5) and apoptosis was significantly reduced in FST288-only females. In addition, FST288-only females are born with more germ cells within the nests. Thus, the excess primordial follicles in FST288-only mice derive from a greater number of germ cells at birth as well as a reduced rate of apoptosis during nest breakdown. These results also demonstrate that FST is critical for normal regulation of germ cell nest breakdown and that loss of the FST303 and/or FST315 isoforms leads to excess primordial follicles with accelerated demise, resulting in premature cessation of ovarian function.

Increased proportion of donor primordial germ cells in chimeric gonads by sterilisation of recipient embryos using busulfan sustained-release emulsion in chickens

2008 ◽  
Vol 20 (8) ◽  
pp. 900 ◽  
Author(s):  
Yoshiaki Nakamura ◽  
Yasuhiro Yamamoto ◽  
Fumitake Usui ◽  
Yusuke Atsumi ◽  
Yohei Ito ◽  
...  
Keyword(s):  
Sustained Release ◽  
Germ Cell ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Sesame Oil ◽  
Chicken Embryos ◽  
Whole Mount ◽  
Phosphate Buffered Saline ◽  
Transfer Study

The aim of the present study was to improve the efficiency of endogenous primordial germ cell (PGC) depletion and to increase the ratio of donor PGCs in the gonads of recipient chicken embryos. A sustained-release emulsion was prepared by emulsifying equal amounts of Ca2+- and Mg2+-free phosphate-buffered saline containing 10% busulfan solubilised in N,N-dimethylformamide and sesame oil, using a filter. Then, 75 μg per 50 μL busulfan sustained-release emulsion was injected into the yolk. To determine the depletion and repopulation of PGCs in the gonads after 6 days incubation, whole-mount immunostaining was performed. The busulfan sustained-release emulsion significantly reduced the number of endogenous PGCs compared with control (P < 0.05). Moreover, the busulfan sustained-release emulsion significantly depleted endogenous PGCs compared with other previously reported busulfan delivery systems (P < 0.05), but with less variation, suggesting that the sustained-release emulsion delivered a consistent amount of busulfan to the developing chicken embryos. The PGC transfer study showed that the proportion of donor PGCs in the gonads of busulfan sustained-release emulsion-treated embryos after 6 days incubation increased 28-fold compared with control. In conclusion, the results demonstrate that exogenous PGCs are capable of migrating and settling in gonads from which endogenous PGCs have been removed using a busulfan sustained-release emulsion.

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