Differential mitosis and degeneration patterns in relation to the alterations in the shape of the embryonic ectoderm of early post-implantation mouse embryos

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 33-51
Author(s):  
R. E. Poelmann
Keyword(s):  
Cell Cycle ◽  
Cell Kinetics ◽  
Tritiated Thymidine ◽  
Primitive Streak ◽  
Cell Number ◽  
Mouse Embryos ◽  
Surface Ectoderm ◽  
Dividing Cells ◽  
Post Implantation ◽  
Embryonic Ectoderm

The shape of the embryonic ectoderm of early post-implantation mouse embryos changes greatly in the period of 6·2–7·3 days post coitum. The subcellular morphology of the embryonic ectoderm remains unchanged, except in the primitive-streak region. Cell kinetics differ between ectodermal regions. These differences may be related to the changes in the shape of the ectoderm. The increase in cell number in the lateral ectoderm (the prospective surface ectoderm) exceeds that in the frontal ectoderm (the future neurectoderm). This is not due to differences in the duration of the cell cycle. It can be explained, however, by the occurrence of different relative numbers of dividing and non-dividing cells. These numbers vary between the two regions. The percentage of non-dividing cells in the frontal ectoderm may reach 45, whereas in the lateral ectoderm this percentage is not higher than 15. Autoradiography in tritiated thymidine-treated embryos combined with the mitotic indices gave us all of the parameters necessary to present a model capable of clarifying the growth of the ectoderm during gastrulation, as well as the changes in the shape of the ectoderm.

Localization and synthesis of alphafoetoprotein in post-implantation mouse embryos

Development ◽  
1978 ◽  
Vol 43 (1) ◽  
pp. 289-313
Author(s):  
M. Dziadek ◽  
E. Adamson
Keyword(s):  
Yolk Sac ◽  
Mouse Embryos ◽  
Visceral Endoderm ◽  
Mouse Embryogenesis ◽  
Visceral Yolk Sac ◽  
Radioactive Labelling ◽  
Post Implantation ◽  
Embryonic Ectoderm ◽  
Embryonic Region

The localization and synthesis of alphafoetoprotein (AFP) during mouse embryogenesis were studied by immunoperoxidase and by immunoprecipitation after radioactive labelling, using an antiserum prepared against AFP. AFP is first detectable in embryos on the 7th day of gestation (7th day embryos). In 7th and 8th day embryos AFP is confined to visceral (proximal) endoderm cells around the embryonic region of the egg cylinder. Visceral extra-embryonic and parietal (distal) endoderm cells do not contain AFP. By the 9th day of gestation AFP is also present in the extra-embryonic ectoderm, mesoderm and embryonic ectoderm cells around the three cavities of the embryo. These tissues do not synthesize AFP when cultured in isolation, but can adsorb AFP when it is added to the medium. On the 12th day of gestation AFP synthesis is confined to the endoderm layer of the visceral yolk sac. It is concluded that the ability to synthesize AFP is a property which is restricted to the visceral endoderm during early post-implantation development. The presence of AFP in other tissues of the embryo appears to be due to adsorption.

Regionalisation of the mouse embryonic ectoderm: allocation of prospective ectodermal tissues during gastrulation

Development ◽  
1989 ◽  
Vol 107 (1) ◽  
pp. 55-67 ◽  
Author(s):  
P.P. Tam
Keyword(s):  
Spinal Cord ◽  
Cell Fate ◽  
Primitive Streak ◽  
Surface Ectoderm ◽  
Lateral Region ◽  
Anterior Midline ◽  
Cranial Neural Crest Cells ◽  
Lateral Mesoderm ◽  
Somitic Mesoderm ◽  
Embryonic Ectoderm

The regionalisation of cell fate in the embryonic ectoderm was studied by analyzing the distribution of graft-derived cells in the chimaeric embryo following grafting of wheat germ agglutinin—gold-labelled cells and culturing primitive-streak-stage mouse embryos. Embryonic ectoderm in the anterior region of the egg cylinder contributes to the neuroectoderm of the prosencephalon and mesencephalon. Cells in the distal lateral region give rise to the neuroectoderm of the rhombencephalon and the spinal cord. Embryonic ectoderm at the archenteron and adjacent to the middle region of the primitive streak contributes to the neuroepithelium of the spinal cord. The proximal-lateral ectoderm and the ectodermal cells adjacent to the posterior region of the primitive streak produce the surface ectoderm, the epidermal placodes and the cranial neural crest cells. Some labelled cells grafted to the anterior midline are found in the oral ectodermal lining, whereas cells from the archenteron are found in the notochord. With respect to mesodermal tissues, ectoderm at the archenteron and the distal-lateral region of the egg cylinder gives rise to rhombencephalic somitomeres, and the embryonic ectoderm adjacent to the primitive streak contributes to the somitic mesoderm and the lateral mesoderm. Based upon results of this and other grafting studies, a map of prospective ectodermal tissues in the embryonic ectoderm of the full-streak-stage mouse embryo is constructed.

scholarly journals Regulation of Fruit Growth and Fruit Size in Apple

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1097A-1097
Author(s):  
Anish Malladi ◽  
Peter Goldsbrough ◽  
Peter Hirst
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Cell Division ◽  
Fruit Development ◽  
Fruit Size ◽  
Cell Number ◽  
Rt Pcr ◽  
Cell Production ◽  
Golden Delicious ◽  
Dividing Cells

Fruit development in apple cultivars varying in their ultimate fruit size was analyzed using cytology, flow cytometry (FCM), and semi-quantitative RT-PCR. Fruit size variation across cultivars was largely explained by variation in cell number. The cell division phase lasted for less than 30 days in all varieties, less than previously believed. A distinct overlap between the cell division and cell expansion phases was present. Analysis of the relative cell production rate (rCPR) showed a major peak about 10 days after full bloom (DAFB) after which it declined. Comparison of the rCPR across varieties suggested distinct patterns of cell production with `Gala' having a low but sustained rCPR, `Pixy Crunch' a short but high rCPR, and `Golden Delicious' having a high and sustained rCPR. FCM analysis also showed similar patterns with a peak in the proportion of dividing cells about 10 DAFB followed by a decline. To further understand regulation of cell number, four cell cycle related genes were cloned from `Gala'. Cyclin Dependent Kinase B (CDK B) and Cyclin B were found to be highly cell division phase specific in their expression. Analysis of gene expression by semi-quantitative RT-PCR indicated peak expression of these two genes at 5-10 DAFB, consistent with the peaks in rCPR and proportion of dividing cells. Comparison of gene expression across the varieties showed higher peak expression of the above genes in the larger-fruited `Golden Delicious' than in the smaller-fruited `Gala.' This study provides novel insight into the regulation of fruit development in apple and also suggests a role for the cell cycle genes in fruit size regulation.

Development of cytochalasin B-induced tetraploid and diploid/tetraploid mosaic mouse embryos

Development ◽  
1977 ◽  
Vol 41 (1) ◽  
pp. 47-64 ◽  
Author(s):  
A. K. Tarkowski ◽  
A. Witkowska ◽  
J. Opas
Keyword(s):  
Embryonic Development ◽  
Embryo Development ◽  
Cytochalasin B ◽  
Primitive Streak ◽  
Cell Number ◽  
Mouse Embryos ◽  
Proliferation Rate ◽  
Foetal Membranes ◽  
Diploid Cells

By subjecting F1 (CBA × C57/BL) × A eggs at the time of 2nd cleavage to 10 μg/ml of cytochalasin B (CB), tetraploidy was produced in 52 % of 2-cell eggs and 35 % of 3-cell eggs. 2n/4n mosaic embryos were produced from 2-, 3- and 4-cell eggs and amounted to 20 % of all treated eggs. 80 % of tetraploid embryos developed in vitro into regular blastocysts with half the cell number of control diploids. The effectiveness of CB in producing tetraploid embryos is limited by the asynchrony of 2nd cleavage, both between eggs and between sister blastomeres. Two-cell presumed tetraploids were transplanted to recipients and examined between the 6th and 11th day of pregnancy. Up to 6½ days development is normal and most embryos form egg-cylinders. At 7½ days the embryonic part of the cylinders is underdeveloped and in later development fails to form an embryo. Development of foetal membranes is much less affected and in the most successfully developing egg-cylinders their formation can be fully accomplished. Failure of embryonic development appears to be due to subnormal activity of the primitive streak, resulting in shortage of mesoderm. Postimplantation development of 2n/4n mosaics was normal. While in embryos tetraploid cells were either absent or in very low proportion (below 4 %), their contribution to the foetal membranes amounted in some cases to up to 50 %. Elimination of tetraploid cells from mosaic embryos suggests that they have a lower proliferation rate than diploid cells.

Expression of Forssman antigen in the post-implantation mouse embryo

Development ◽  
1981 ◽  
Vol 61 (1) ◽  
pp. 117-131
Author(s):  
M. G. Stinnakre ◽  
M. J. Evans ◽  
K. R. Willison ◽  
P. L. Stern
Keyword(s):  
Sertoli Cells ◽  
Inner Cell Mass ◽  
Primordial Germ Cells ◽  
Cell Mass ◽  
Mouse Embryos ◽  
Related Distribution ◽  
Forssman Antigen ◽  
Post Implantation ◽  
Embryonic Ectoderm ◽  
Positive Population

The expression of Forssman antigen on the surface of cells of post-implantation mouse embryos between 5 and 7½ days old and of cells of the gonads from 10½ days has been followed using the monoclonal antiserum M1/22.25. In the early post-implantation embryo a lineage-related distribution is found. The inner cell mass of the blastocyst was previously shown to be Forssman antigen positive and its derivative tissues the epiblast of the 5-day embryo and the primary embryonic endoderm are also positive. The endoderm cells remain positive both over the embryonic and extraembryonic portions of the embryo but the epiblast becomes Forssman antigen negative as it differentiates into embryonic ectoderm. The extraembryonic ectoderm which is derived from the Forssman negative trophectoderm remains negative throughout. The primordial germ cells are Forssman antigen positive from their first appearance in the germinal ridge until day 14 when they become negative but after that time it is other cells not related by direct lineage which become Forssman antigen positive. These are tentatively identified as Sertoli cells precursors as it is the Sertoli cells which are the antigen-positive population in the adult testis.

Mitosis and the Cell Cycle in the Metamorphic Moult of the Milkweed Bug, Oncopeltus Fasciatus.: A Radioautographic Study

1968 ◽  
Vol 3 (3) ◽  
pp. 391-404
Author(s):  
P. A. LAWRENCE
Keyword(s):  
Cell Cycle ◽  
Mother Cell ◽  
Tritiated Thymidine ◽  
Cell Number ◽  
Oncopeltus Fasciatus ◽  
Simple Method ◽  
Milkweed Bug ◽  
Whole Mount ◽  
S Period ◽  
Equivalent Method

A simple method of whole-mount radioautography is devised to investigate aspects of the cell cycle during metamorphosis in the epidermis of the milkweed bug, Oncopeltus. Tritiated thymidine is used to indicate DNA synthesis. As the label only lasts in the insect for about 2 h, a wave of labelled cells passes through the different phases of the cell cycle. The S period is found to overlap with an exceptionally long prophase and there is thus no G2 period. The length of prophase (408±10 min) is estimated from a plot of the fraction of labelled prophases against time after injection of label. By an equivalent method the length of the S period is found to be 289±12 min. No labelled cells divide again until about 24 h after the previous mitosis, when some cells embark on a second mitosis. The minimum interphase (G1 period is approximately 16 h. In the area studied, the cell number more than doubles during the proliferative mitoses; and it is thus possible, but not certain, that every cell divides at least once. Fifth-stage larvae injected during the differentiative divisions (which are involved in the development of dense hairs) show that each of the three kinds of differentiative divisions has its own peculiar timing. The timing of the very first division, that of the epidermal cell which will become the hair mother cell, suggests that the cell is already different from its progenitors prior to prophase.

RELATION BETWEEN CELL CYCLE AND YIELD OF ABERRATIONS OBSERVED IN IRRADIATED HUMAN LYMPHOCYTES

1979 ◽  
Vol 21 (4) ◽  
pp. 473-478 ◽  
Author(s):  
A. Leonard ◽  
G. Decat
Keyword(s):  
Cell Cycle ◽  
Cell Kinetics ◽  
Human Lymphocytes ◽  
Mitotic Division ◽  
Fixation Time ◽  
X Rays ◽  
Mitotic Delay ◽  
Dividing Cells ◽  
Ionizing Radiations ◽  
Pha Stimulation

The bromodeoxyuridine-Giemsa technique has been used to study systematically the incidence of cells in first or subsequent mitoses at different fixation times of human lymphocyte control cultures as well as the influence of ionizing radiations on cell kinetics. Second divisions appear (3%) in cultures harvested 48 h after initiation. In 72 h cultures 40% of the dividing cells are in second and 33% in third division. Administration of 200 rads of X-rays before PHA stimulation results in a mitotic delay but does not increase the incidence of SCE. The yield of dicentrics after an exposure to 200 rads was the same for all cells in first mitosis regardless of fixation time. These results demonstrate that there is no evidence for the existence of sensitive subpopulations that could be distinguished by the time of the first mitotic division following stimulation.

Chimaerism of primordial germ cells in the early postimplantation mouse embryo following microsurgical grafting of posterior primitive streak cells in vitro

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 95-115
Author(s):  
Andrew J. Copp ◽  
Heather M. Roberts ◽  
Paul E. Polani
Keyword(s):  
Mouse Embryo ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Experimental System ◽  
Primitive Streak ◽  
Mouse Embryos ◽  
Culture Methods ◽  
Surface Ectoderm ◽  
Intact Mouse

A microsurgical grafting technique has been used to introduce primordial germ cell (PGC) precursors into intact primitive-streak-stage mouse embryos in vitro. Operated embryos were cultured for 36–40 h and then analysed by a combined histochemical and autoradiographic method. PGC chimaerism occurred in embryos that received grafts of caudal primitive streak cells but not adjacent embryonic endoderm or anterolateral ectoderm/mesoderm cells. Graftderived PGCs were found to be migrating through the gut endoderm alongside host-derived PGCs in approximately half of the chimaeric embryos whereas in the other 50% of cases PGCs remained at the site of grafting in association with graft-derived somatic cells. A similar pattern of somatic chimaerism was produced by primitive streak and anterolateral ectoderm/mesoderm grafts: the allantois was colonized predominantly, with, in addition, formation of amnion, surface ectoderm and caudal mesoderm in a few embryos. The majority of embryonic endoderm grafts failed to incorporate into host embryos and formed yolk-sac-like vesicles. The findings of this study indicate that (a) PGCs originate from the embryonic ectoderm via the primitive streak during development of the mouse embryo, and (b) anterolateral ectoderm and mesoderm cells are unable to form PGCs after heterotopic grafting to the posterior primitive streak site. The combined microsurgical and embryo culture methods provide an experimental system for the analysis of PGC development in intact mouse embryos.

An autoradiographic analysis of the potency of embryonic ectoderm in the 8th day postimplantation mouse embryo

Development ◽  
1981 ◽  
Vol 64 (1) ◽  
pp. 87-104
Author(s):  
R. S. P. Beddington
Keyword(s):  
Tritiated Thymidine ◽  
Donor Cell ◽  
Primitive Streak ◽  
Donor Cells ◽  
Stage Embryo ◽  
Autoradiographic Analysis ◽  
Embryonic Ectoderm

The potency of 8th day mouse embryonic ectoderm cells has been studied by injecting them into synchronous embryos which were subsequently cultured for 36 h. The development of injected embryos in vitro was comparable to that of embryos maintained in vivo. Tritiated thymidine was used to label the donor cells so that chimaerism could be analysed histologically. The results demonstrate the pluripotency of embryonic ectoderm in situ in the late primitive-streak-stage embryo. In addition, the patterns of donor cell colonization vary according to the site of origin and injection of the donor tissue.

scholarly journals Requirement for β-Catenin in Anterior-Posterior Axis Formation in Mice

2000 ◽  
Vol 148 (3) ◽  
pp. 567-578 ◽  
Author(s):  
Joerg Huelsken ◽  
Regina Vogel ◽  
Volker Brinkmann ◽  
Bettina Erdmann ◽  
Carmen Birchmeier ◽  
...  
Keyword(s):  
Wnt Pathway ◽  
Wnt Signaling Pathway ◽  
Primitive Streak ◽  
Mouse Embryos ◽  
Axis Formation ◽  
Deficient Mouse ◽  
Visceral Endoderm ◽  
Embryonic Ectoderm ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

The anterior-posterior axis of the mouse embryo is defined before formation of the primitive streak, and axis specification and subsequent anterior development involves signaling from both embryonic ectoderm and visceral endoderm. Τhe Wnt signaling pathway is essential for various developmental processes, but a role in anterior-posterior axis formation in the mouse has not been previously established. β-Catenin is a central player in the Wnt pathway and in cadherin-mediated cell adhesion. We generated β-catenin–deficient mouse embryos and observed a defect in anterior-posterior axis formation at embryonic day 5.5, as visualized by the absence of Hex and Hesx1 and the mislocation of cerberus-like and Lim1 expression. Subsequently, no mesoderm and head structures are generated. Intercellular adhesion is maintained since plakoglobin substitutes for β-catenin. Our data demonstrate that β-catenin function is essential in anterior-posterior axis formation in the mouse, and experiments with chimeric embryos show that this function is required in the embryonic ectoderm.

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