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).

scholarly journals X chromosome activity in female germ cells of mice heterozygous for Searle's translocation T(X;16)16H

1981 ◽  
Vol 37 (3) ◽  
pp. 317-322 ◽  
Author(s):  
P. G. Johnston
Keyword(s):  
X Chromosome ◽  
Germ Cells ◽  
Meiotic Prophase ◽  
Somatic Cells ◽  
Phosphoglycerate Kinase ◽  
Inactive X Chromosome ◽  
Faint Band

SUMMARYThe expression of X-linked phosphoglycerate kinase (PGK-1) in germ cells from embryos heterozygous for both PGK-1 and Searle's translocation T(X; 16) 16H was examined to investigate X chromosome activity during oogenesis. The Pgk-lb allele on the translocated X chromosome was the only allele active in somatic cells of all embryos and in germ cells from 12·5 d.p.c. embryos. However, an additional faint band representing Pgk-la activity was observed in germ cells from older embryos (13·5–18·5 d.p.c.) and neonates (1–2 d.p.p.). It is concluded that there is a period when only one X chromosome is active in early female germ cells and that reactivation of the inactive X chromosome takes place just prior to meiotic prophase.

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.

scholarly journals Müllerian Inhibiting Substance Is Required for Germ Cell Proliferation during Early Gonadal Differentiation in Medaka (Oryzias latipes)

Endocrinology ◽  
2007 ◽  
Vol 149 (4) ◽  
pp. 1813-1819 ◽  
Author(s):  
Eri Shiraishi ◽  
Norifumi Yoshinaga ◽  
Takeshi Miura ◽  
Hayato Yokoi ◽  
Yuko Wakamatsu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Germ Cell ◽  
Germ Cells ◽  
Sex Differentiation ◽  
Somatic Cells ◽  
Oryzias Latipes ◽  
Cell Number ◽  
Gonadal Differentiation ◽  
Loss Of Function ◽  
Germ Cell Proliferation

Müllerian inhibiting substance (MIS) is a glycoprotein belonging to the TGF-β superfamily. In mammals, MIS is responsible for the regression of Müllerian ducts in the male fetus. However, the role of MIS in gonadal sex differentiation of teleost fish, which have no Müllerian ducts, has yet to be clarified. In the present study, we examined the expression pattern of mis and mis type 2 receptor (misr2) mRNAs and the function of MIS signaling in early gonadal differentiation in medaka (teleost, Oryzias latipes). In situ hybridization showed that both mis and misr2 mRNAs were expressed in the somatic cells surrounding the germ cells of both sexes during early sex differentiation. Loss-of-function of either MIS or MIS type II receptor (MISRII) in medaka resulted in suppression of germ cell proliferation during sex differentiation. These results were supported by cell proliferation assay using 5-bromo-2′-deoxyuridine labeling analysis. Treatment of tissue fragments containing germ cells with recombinant eel MIS significantly induced germ cell proliferation in both sexes compared with the untreated control. On the other hand, culture of tissue fragments from the MIS- or MISRII-defective embryos inhibited proliferation of germ cells in both sexes. Moreover, treatment with recombinant eel MIS in the MIS-defective embryos dose-dependently increased germ cell number in both sexes, whereas in the MISRII-defective embryos, it did not permit proliferation of germ cells. These results suggest that in medaka, MIS indirectly stimulates germ cell proliferation through MISRII, expressed in the somatic cells immediately after they reach the gonadal primordium.

Neonatal administration of diethylstilbestrol has adverse effects on somatic cells rather than germ cells

2006 ◽  
Vol 22 (4) ◽  
pp. 746-753 ◽  
Author(s):  
Kyu-Bom Koh ◽  
Yoshiro Toyama ◽  
Masatoshi Komiyama ◽  
Tetsuya Adachi ◽  
Hideki Fukata ◽  
...  
Keyword(s):  
Adverse Effects ◽  
Germ Cells ◽  
Somatic Cells ◽  
Neonatal Administration

fringeandNotchspecify polar cell fate duringDrosophilaoogenesis

Development ◽  
2001 ◽  
Vol 128 (12) ◽  
pp. 2243-2253 ◽  
Author(s):  
Muriel Grammont ◽  
Kenneth D. Irvine
Keyword(s):  
Cell Fate ◽  
Null Allele ◽  
Somatic Cells ◽  
Ectopic Expression ◽  
Notch Receptor ◽  
Drosophila Oogenesis ◽  
Early Stages ◽  
Polar Cell ◽  
Hypomorphic Alleles ◽  
Notch Activation

fringe encodes a glycosyltransferase that modulates the ability of the Notch receptor to be activated by its ligands. We describe studies of fringe function during early stages of Drosophila oogenesis. Animals mutant for hypomorphic alleles of fringe contain follicles with an incorrect number of germline cells, which are separated by abnormally long and disorganized stalks. Analysis of clones of somatic cells mutant for a null allele of fringe localizes the requirement for fringe in follicle formation to the polar cells, and demonstrates that fringe is required for polar cell fate. Clones of cells mutant for Notch also lack polar cells and the requirement for Notch in follicle formation appears to map to the polar cells. Ectopic expression of fringe or of an activated form of Notch can generate an extra polar cell. Our results indicate that fringe plays a key role in positioning Notch activation during early oogenesis, and establish a function for the polar cells in separating germline cysts into individual follicles.

scholarly journals Number of germ cells and meiotic prophase stages in fetal rat ovaries cultured in vitro

Reproduction ◽  
1985 ◽  
Vol 73 (2) ◽  
pp. 579-583 ◽  
Author(s):  
J. Prepin ◽  
C. Gibello-Kervran ◽  
G. Charpentier ◽  
A. Jost
Keyword(s):  
Germ Cells ◽  
Meiotic Prophase ◽  
Fetal Rat

scholarly journals Andrew Johnson (1958-2021)

Development ◽  
2021 ◽  
Vol 148 (22) ◽  
Author(s):  
Robert Lloyd ◽  
Ramiro Alberio ◽  
Brian I. Crother
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Early Stages

ABSTRACT Andrew Johnson, a pioneer in the development of the amphibian axolotl as a model to study the early stages of metazoan development, died 15th September 2021. Known as ‘AJ’ by his family, and by his friends and colleagues, his older sister Pam referred to him as an unstoppable ‘force of nature’ who at the age of 9 or 10 said to her, ‘I'm going to become a professor’. Here, we reflect on AJ's life and work, paying particular attention to his studies on the establishment of primordial germ cells in vertebrates.

scholarly journals Two Alternative Mechanisms That Regulate the Presentation of Apoptotic Cell Engulfment Signal in Caenorhabditis elegans

2007 ◽  
Vol 18 (8) ◽  
pp. 3180-3192 ◽  
Author(s):  
Victor Venegas ◽  
Zheng Zhou
Keyword(s):  
Caenorhabditis Elegans ◽  
Abc Transporter ◽  
Germ Cells ◽  
Mammalian Cells ◽  
Developmental Stages ◽  
Apoptotic Cell ◽  
Somatic Cells ◽  
Apoptotic Cells ◽  
Phospholipid Scramblase ◽  
Cell Engulfment

Phosphatidylserine exposed on the surface of apoptotic mammalian cells is considered an “eat-me” signal that attracts phagocytes. The generality of using phosphatidylserine as a clearance signal for apoptotic cells in animals and the regulation of this event remain uncertain. Using ectopically expressed mouse MFG-E8, a secreted phosphatidylserine-binding protein, we detected specific exposure of phosphatidylserine on the surface of apoptotic cells in Caenorhabditis elegans. Masking the surface phosphatidylserine inhibits apoptotic cell engulfment. CED-7, an ATP-binding cassette (ABC) transporter, is necessary for the efficient exposure of phosphatidylserine on apoptotic somatic cells, and for the recognition of these cells by phagocytic receptor CED-1. Alternatively, phosphatidylserine exposure on apoptotic germ cells is not CED-7 dependent, but instead requires phospholipid scramblase PLSC-1, a homologue of mammalian phospholipid scramblases. Moreover, deleting plsc-1 results in the accumulation of apoptotic germ cells but not apoptotic somatic cells. These observations suggest that phosphatidylserine might be recognized by CED-1 and act as a conserved eat-me signal from nematodes to mammals. Furthermore, the two different biochemical activities used in somatic cells (ABC transporter) and germ cells (phospholipid scramblase) suggest an increased complexity in the regulation of phosphatidylserine presentation in response to apoptotic signals in different tissues and during different developmental stages.

Sex differentiation of germ cells in the teleost, Oryzias latipes, during normal embryonic development

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 385-395
Author(s):  
Noriyuki Satoh ◽  
Nobuo Egami
Keyword(s):  
Germ Cells ◽  
Meiotic Prophase ◽  
Sex Differentiation ◽  
Primordial Germ Cells ◽  
Oryzias Latipes ◽  
The Other ◽  
Histological Structure ◽  
The Mean ◽  
Further Development ◽  
Normal Embryonic Development

Mitotic and meiotic activities of germ cells during early development in the medaka, Oryzias latipes, are dealt with in this report. Primordial germ cells were obviously distinguishable from somatic cells 3 days after fertilization and began to proliferate about 7 days after fertilization. The mean number of primordial germ cells increased during a period of 7–10 days after fertilization, reaching about 90 immediately before hatching. Newly hatched fry could be classified into two types according to the number and the nucleic activity of germ cells in the gonadal rudiment. One type consisted of fry containing about 100 germ cells and no cells in the meiotic prophase. In the other type of fry the number of germ cells increased by mitotic divisions and some of the cells began to enter into the meiotic prophase. During the course of further development the fry of the former type differentiated into males and the latter into females. Therefore it can be concluded that the morphological sex differentiation of germ cells occurs at the time of hatching. However, no sexual differences in the histological structure of somatic elements in the gonad are observable at that time.

Evidence of male germ cell redifferentiation into female germ cells in planarian regeneration

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 29-36
Author(s):  
V. Gremigni ◽  
M. Nigro ◽  
I. Puccinelli
Keyword(s):  
Germ Cells ◽  
Somatic Cells ◽  
The Body ◽  
Diploid Male ◽  
Female Gonad ◽  
Anterior Portion ◽  
Male Germ Cells ◽  
Blastema Formation ◽  
Planarian Regeneration ◽  
Undifferentiated Cells

The source and fate of blastema cells are important and still unresolved problems in planarian regeneration. In the present investigation we have attempted to obtain new evidence of cell dedifferentiation-redifferentiation by using a polyploid biotype of Dugesia lugubris s.1. This biotype is provided with a natural karyological marker which allows the discrimination of triploid embryonic and somatic cells from diploid male germ cells and from hexaploid female germ cells. Thanks to this cell mosaic we previously demonstrated that male germ cells take part in blastema formation and are then capable of redifferentiating into somatic cells. In the present investigation sexually mature specimens were transected behind the ovaries and the posterior stumps containing testes were allowed to regenerate the anterior portion of the body. Along with the usual hexaploid oocytes, a small percentage (3.2%) of tetraploid oocytes were produced from regenerated specimens provided with new ovaries. By contrast only hexaploid oocytes were produced from control untransected specimens. The tetraploid oocytes are interpreted as original diploid male germ cells which following the transection take part in blastema formation and then during regeneration redifferentiate into female germ cells thus doubling their chromosome number as usual for undifferentiated cells entering the female gonad in this biotype.

Sign in / Sign up

Export Citation Format

Share Document