Primordial germ cells and oocytes of Branchiostoma virginiae (Cephalochordata, Acrania) are flagellated epithelial cells: relationship between epithelial and primary egg polarity

Zygote ◽  
1997 ◽  
Vol 5 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Jennifer E. Frick ◽  
Edward E. Ruppert
Keyword(s):  
Epithelial Cells ◽  
Basal Lamina ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Germinal Epithelium ◽  
Connective Tissue Layer ◽  
Adult Ovary ◽  
Striated Rootlet ◽  
Egg Polarity

SummaryPrimordial germ cells (PGCs) are described from the gonad of c. 2 cm juvenile Branchiostoma virginiae; early oocytes (c. 10 μm) and enlarging, previtellogenic oocytes (c. 35 μm) are described from the ovary of c. 5 cm adults. The germinal epithelium of the juvenile gonad and adult ovary is composed of both germinal and somatic cells. In the juvenile, somatic cells retain contact with the basal lamina of the germinal epithelium though their perikarya may be displaced towards the lumen; the germinal epithelium is, therefore, a simple but pseudostratified epithelium. In the adult ovary, somatic cells may lose contact with the basal lamina and the epithelium appears to become stratified. PGCs and oocytes are identified as germ cells by the presence of nuage. PGCs and oocytes are polarised epithelial cells. They rest on a basal lamina, extend apically towards a lumen, form adhering junctions with neighbouring cells, and exhibit apical-basal polarity. PGCs and early oocytes have an apical flagellum with an associated basal body, accessory centriole, and one or more striated rootlet fibres. The flagellum is surrounded by a collar of microvilli. Once oocytes begin to enlarge and bulge basally into the connective tissue layer, the flagellum is lost, but the basal bodies and ciliary rootlets are present at the apex of 35 μm oocytes. Similarities of the oogenic pattern in cephalochordates and echinoderms indicate that the establishment of egg polarity in deuterostomes is influenced by the polarity of the germinal epithelium.

Developmental expression of c-kit, a proto-oncogene encoded by the W locus

Development ◽  
1990 ◽  
Vol 109 (4) ◽  
pp. 911-923 ◽  
Author(s):  
A. Orr-Urtreger ◽  
A. Avivi ◽  
Y. Zimmer ◽  
D. Givol ◽  
Y. Yarden ◽  
...  
Keyword(s):  
Germ Cells ◽  
Receptor Tyrosine Kinase ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Mouse Embryos ◽  
Developmental Expression ◽  
Male Germ Line ◽  
Polypeptide Growth Factors ◽  
Adult Ovary

Developmental expression of the c-kit proto-oncogene, a receptor tyrosine kinase encoded by the W locus, was investigated by in situ hybridization in normal mouse embryos. Early after implantation transcripts were detectable only in the maternal placenta (6 1/2-7 1/2 days p.c.). Subsequently (8 1/2 days p.c.) numerous ectodermal (neural tube, sensory placodes) and endodermal (embryonic gut) derivatives expressed c-kit. Later transcripts were detected also in the blood islands of the yolk sac and in the embryonic liver, the main sites of embryonic hemopoiesis. Around midgestation, transcripts accumulated in the branchial pouches and also in primordial germ cells of the genital ridges. This complex pattern of expression remained characteristic also later in gestation, when c-kit was expressed in highly differentiated structures of the craniofacial area, in presumptive melanoblasts and in the CNS. In the adult ovary, maternal c-kit transcripts were detected. They were present in the oocytes of both immature and mature ovarian follicles, but not in the male germ line, where c-kit expression may be down regulated. Thus, c-kit activity is complex and appears in multiple tissues including those that also display defects in mutations at the W locus where c-kit is encoded. Correlation between W phenotypes and c-kit expression, as well as the regulation of the complex and multiple expression of polypeptide growth factors and receptors, is discussed.

scholarly journals Specification of the germline by Nanos-dependent down-regulation of the somatic synMuvB transcription factor LIN-15B

2017 ◽  
Author(s):  
Chih-Yung S. Lee ◽  
Tu Lu ◽  
Geraldine Seydoux
Keyword(s):  
Transcription Factor ◽  
Germ Cells ◽  
Rna Binding ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Rna Binding Protein ◽  
Dependent Manner ◽  
Embryonic Cells ◽  
C Elegans ◽  
Underlying Mechanisms

AbstractThe Nanos RNA-binding protein has been implicated in the specification of primordial germ cells (PGCs) in metazoans, but the underlying mechanisms remain poorly understood. We have profiled the transcriptome of PGCs lacking the nanos homologues nos-1 and nos-2 iC. elegans. nos-1nos-2 PGCs fail to silence hundreds of genes normally expressed in oocytes and somatic cells, a phenotype reminiscent of PGCs lacking the repressive PRC2 complex. The nos-1nos-2 phenotype depends on LIN-15B, a broadly expressed synMuvB class transcription factor known to antagonize PRC2 activity in somatic cells. LIN-15B is maternally-inherited by all embryonic cells and is down-regulated specifically in PGCs in a nos-1nos-2-dependent manner. Consistent with LIN-15B being a critical target of Nanos regulation, inactivation of maternal LIN-15B restores fertility to nos-1nos-2 mutants. These studies demonstrate a central role for Nanos in reprogramming the transcriptome of PGCs away from an oocyte/somatic fate by down-regulating an antagonist of PRC2 activity.

scholarly journals Characterization of Telomeric Repeat-Containing RNA (TERRA) localization and protein interactions in Primordial Germ Cells of the mouse

2018 ◽  
Author(s):  
Miguel Angel Brieno-Enriquez ◽  
Stefannie L. Moak ◽  
Anyul Abud-Flores ◽  
Paula Elaine Cohen
Keyword(s):  
Germ Cells ◽  
Protein Interactions ◽  
Gestational Age ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Telomeric Repeat ◽  
Telomere Maintenance ◽  
Interacting Proteins ◽  
Dna Repeats ◽  
Rna Fish

Telomeres are dynamic nucleoprotein structures capping the physical ends of linear eukaryotic chromosomes. They consist of telomeric DNA repeats (TTAGGG), the shelterin protein complex, and Telomeric Repeat-Containing RNA (TERRA). Proposed TERRA functions are wide-ranging and include telomere maintenance, telomerase inhibition, genomic stability, and alternative lengthening of telomere. However, the role of TERRA in primordial germ cells (PGCs), the embryonic precursors of germ cells, is unknown. Using RNA-fluorescence in situ hybridization (RNA-FISH) we identify TERRA in PGCs soon after these cells have migrated to, and become established in, the developing gonad. RNA-FISH showed the presence of TERRA transcripts in female PGCs at 11.5, 12.5 and 13.5 days post-coitum. In male PGCs, however, TERRA transcripts are observable from 12.5 dpc. Using qPCR we evaluated chromosome-specific TERRA expression, and demonstrated that TERRA levels vary with sex and gestational age, and that transcription of TERRA from specific chromosomes is sexually dimorphic. TERRA interacting proteins were evaluated using Identification of Direct RNA Interacting Proteins (iDRiP) which identified 48 in female and 26 in male protein interactors specifically within nuclear extracts from PGCs at 13.5 dpc. We validated two different proteins the splicing factor, proline- and glutamine-rich (SFPQ) in PGCs and Non-POU domain-containing octamer-binding protein (NONO) in somatic cells. Our results show that, TERRA interacting proteins are determined by sex in both PGCs and somatic cells. Taken together, our data indicate that TERRA expression and interactome during PGC development are regulated in a dynamic fashion that is dependent on gestational age and sex.

scholarly journals The Central Role of Cadherins in Gonad Development, Reproduction and Fertility

2020 ◽  
Author(s):  
Rafał P. Piprek ◽  
Malgorzata Kloc ◽  
Paulina Mizia ◽  
Jacek Z. KUBIAK
Keyword(s):  
Germ Cells ◽  
Reproductive Tract ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Gonad Development ◽  
Female Reproductive Tract ◽  
Future Research ◽  
Corpora Lutea ◽  
Germline Development

Cadherins are a group of membrane proteins responsible for cell adhesion. They are crucial for cell sorting and recognition during the morphogenesis, but also play many other roles such as assuring tissue integrity and resistance to stretching, mechanotransduction, cell signaling, regulation of cell proliferation, apoptosis, survival, carcinogenesis, etc. Within the cadherin superfamily, the E- and N-cadherin have been especially well studied. They are involved in many aspects of sexual development and reproduction, such as germline development and gametogenesis, gonad development and functioning, and fertilization. E-cadherin is expressed in the primordial germ cells, (PGCs) and also participates in PGC migration to the developing gonads where they become enclosed by the N-cadherin-expressing somatic cells. The differential expression of cadherins is also responsible for the establishment of the testis or ovary structure. In the adult testes, the N-cadherin is responsible for the integrity of the seminiferous epithelium, regulation of sperm production, and the establishment of the blood-testis barrier. Sex hormones regulate the expression and turnover of N-cadherin influencing the course of spermatogenesis. In the adult ovaries, E- and N-cadherin assure the integrity of ovarian follicles and the formation of corpora lutea. Cadherins are expressed in the mature gametes, and facilitate the capacitation of sperm in the female reproductive tract, and gamete contact during fertilization. The germ cells and accompanying somatic cells express a series of different cadherins, however, their role in gonads and reproduction is still unknown. In this review, we show what is known and unknown about the role of cadherins in the germline and gonad development, and suggest the topics for future research.

46 Morphologic and functional characterization of the early fetal equine gonads

2019 ◽  
Vol 31 (1) ◽  
pp. 149
Author(s):  
D. Scarlet ◽  
I. Walter ◽  
S. Handschuh ◽  
R. Ellerbrock ◽  
I. Canisso ◽  
...  
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Functional Characterization ◽  
Basal Membrane ◽  
Interstitial Cells ◽  
Germinal Epithelium ◽  
Surface Epithelium ◽  
Seminiferous Tubules ◽  
Stem Cell Markers ◽  
And Function

In the equine embryo, putative primordial germ cells appear between 20 and 30 days and the gonadal primordium can first be identified at Day 30 after ovulation, respectively. Subsequently, sexual differentiation of the gonad occurs and completes by Day 45 of pregnancy. The objectives of this work were to describe the morphology and function of the fetal equine ovary and testis at the beginning of the fetal stage of pregnancy. For this purpose, 12 equine fetuses (6 males and 6 females) were collected at 45 days (n=1, female), 50 days (n=1, male), and 60 days (n=10, 5 males and 5 females) after ovulation, respectively. A high attention was given to Day 60 because it is the representative time for fetal sex determination in horses by transrectal ultrasonography. Conceptuses were collected transcervically by uterine lavage and fixed in 4% formaldehyde before being prepared for morphology analysis and immunohistochemistry assay. Gonads were identified and immunostained for anti-Müllerian hormone (AMH), Ki67, CD117, LIN28, vimentin, cytokeratin, and laminin. In all fetuses, gonads were situated in a sublumbar localisation and connected with the mesonephros. In females, primordial germ cells were localised close to the surface germinal epithelium, whereas in males the primordial germ cells were organised in cord-like clusters-the future seminiferous tubules. At this stage, interstitial cells predominate in the testes. The AMH staining was strongly expressed in the fetal testis, but was completely absent from the fetal ovary. Protein expression of mitosis marker Ki67 was localised in primordial germ cells of both sexes. Moreover, stem cell markers LIN28 and CD117 were also present in the gonads. In females, these proteins were not only localised in some of the primordial germ cells, but also in the surface germinal epithelium, whereas in males LIN28 and CD117 were immunolocalized in the seminiferous tubules, distant from the surface epithelium. Vimentin was strongly expressed in the interstitial cells of the gonads of both sexes. Using laminin staining, basal membrane of the seminiferous tubules in males and of primordial germ cells in females could be visualised. In females, the basal membrane of primordial germ cells also stained positive for cytokeratin, whereas in males no cytokeratin staining was seen around seminiferous tubules. Moreover, the surface germinal epithelium of both sexes stained positive for cytokeratin. This study widely extends existing knowledge about morphology, development, and function of the early fetal equine gonad. Presence of stem cells could be clearly demonstrated in the gonads of both sexes, whereas AMH staining clearly distinguished between males and females, confirming the important role of this hormone for gonadal and reproductive tract differentiation.

Oogenesis in adult prosimians

Development ◽  
1967 ◽  
Vol 17 (1) ◽  
pp. 139-145
Author(s):  
J. M. Ioannou
Keyword(s):  
Germ Cells ◽  
Meiotic Prophase ◽  
Somatic Cells ◽  
Germinal Epithelium ◽  
Mammalian Development ◽  
Direct Transformation ◽  
Early Stages ◽  
Daubentonia Madagascariensis ◽  
Galago Senegalensis ◽  
Loris Tardigradus

It is widely accepted that oogenesis normally stops early in mammalian development (see Brambell, 1956; Franchi, Mandl & Zuckerman, 1962). Nevertheless, it has been claimed that mitotically active oogonia, and oocytes in early stages of meiotic prophase occur in mature specimens of Galago senegalensis (Gérard, 1920, 1932; Gérard & Herlant, 1953; Herlant, 1961; Petter-Rousseaux, 1962; Butler, 1964), G. crassicaudatus (Gérard & Herlant, 1953), G. demidoffi (Gérard, 1932; Gérard & Herlant, 1953; Petter-Rousseaux, 1962), Perodicticus potto (Gérard & Herlant, 1953), Loris tardigradus lydekkerianus (Rao, 1927; Brambell, 1930), and Daubentonia madagascariensis (Petter-Rousseaux & Bourlière, 1965). The latter is a lemuroid prosimian, while all the others are lorisoids (Hill, 1953). It has also been asserted that new germ cells are formed by direct transformation from the somatic cells of the ovarian germinal epithelium (Gérard, 1920, 1932; Rao, 1927; Gérard & Herlant, 1953).

Sexually dimorphic development of mouse primordial germ cells: switching from oogenesis to spermatogenesis

Development ◽  
2002 ◽  
Vol 129 (5) ◽  
pp. 1155-1164 ◽  
Author(s):  
Ian R. Adams ◽  
Anne McLaren
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Prostaglandin D2 ◽  
Sexually Dimorphic ◽  
Paracrine Factor ◽  
Genital Ridge ◽  
Supporting Cells ◽  
Signalling Molecule ◽  
Female Genital

During embryogenesis, primordial germ cells (PGCs) have the potential to enter either spermatogenesis or oogenesis. In a female genital ridge, or in a non-gonadal environment, PGCs develop as meiotic oocytes. However, male gonadal somatic cells inhibit PGCs from entering meiosis and direct them to a spermatogenic fate. We have examined the ability of PGCs from male and female embryos to respond to the masculinising environment of the male genital ridge, defining a temporal window during which PGCs retain a bipotential fate. To help understand how PGCs respond to the male gonadal environment, we have identified molecular differences between male PGCs that are committed to spermatogenesis and bipotential female PGCs. Our results suggest that one way in which PGCs respond to this masculinising environment is to synthesise prostaglandin D2. We show that this signalling molecule can partially masculinise female embryonic gonads in culture, probably by inducing female supporting cells to differentiate into Sertoli cells. In the developing testis, prostaglandin D2 may act as a paracrine factor to induce Sertoli cell differentiation. Thus part of the response of PGCs to the male gonadal environment is to generate a masculinising feedback loop to ensure male differentiation of the surrounding gonadal somatic cells.

Production of Clone-like Chicken by Primordial Germ Cells Induced From Somatic Cells

2021 ◽  
Author(s):  
Ruifeng Zhao ◽  
Qisheng Zuo ◽  
Xia Yuan ◽  
Kai Jin ◽  
Yani Zhang ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Somatic Cells ◽  
Bird Species ◽  
Unique Characteristic ◽  
Practical Application ◽  
Reprogramming Factors ◽  
First Time

Abstract The chicken primordial germ cell (PGCs) has the unique characteristic of settling in gonad through blood migration, which was the only way to realize the recovery of bird species. However, the PGCs obtained from a single embryo was far from enough to meet the practical application, while somatic cells can be obtained in large quantities. Therefore, the problem of insufficient PGCs can be solved by the induction of somatic cells into PGCs. Here, we successfully transdifferentiate somatic cells into PGCs, which can be transplanted to the recipient to produce offspring. In detail, The CEF of Black-Feathered Langshan Chicken was reprogrammed into iPS by reprogramming factors Oct4, Sox2, Nanog and Lin28, then was induced into PGCs by BMP4/BMP8b/EGF system. The induced PGCs has similar biological characteristics to the primary PGCs, which was transplanted into White Plymouth Rock Chicken, which self-crossed to produce clone-like offspring. It was the the first time to demonstrate the feasibility of avian cloning from somatic cells.

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