scholarly journals Immunohistochemical and ultrastructural characterization of the initial post-hatching development of bovine embryos

Reproduction ◽  
2003 ◽  
pp. 607-623 ◽  
Author(s):  
P Maddox-Hyttel ◽  
NI Alexopoulos ◽  
G Vajta ◽  
I Lewis ◽  
P Rogers ◽  
...  
Keyword(s):  
Tight Junctions ◽  
Cell Mass ◽  
Primitive Streak ◽  
Definitive Endoderm ◽  
Basic Knowledge ◽  
Germ Layer ◽  
Bovine Embryos ◽  
Layer Formation ◽  
Trophoblast Cells ◽  
Amniotic Cavity

The problems of sustaining placenta formation in embryos produced by nuclear transfer have emphasized the need for basic knowledge about epiblast formation and gastrulation in bovine embryos. The aims of this study were to define stages of bovine post-hatching embryonic development and to analyse functional mechanisms of germ-layer formation. Embryos developed in vivo were collected after slaughter from superovulated cows on days 9, 11, 14 and 21 after insemination and processed for transmission electron microscopy (n = 26) or immunohistochemistry (n = 27) for potential germ-layer characterization (cytokeratin 8 for potential ectoderm; alpha-1-fetoprotein for potential endoderm; and vimentin for potential mesoderm). On day 9, the embryos were devoid of zona pellucida and presented a well-defined inner cell mass (ICM), which was covered by a thin layer of trophoblast cells (the Rauber's layer). Formation of the hypoblast from the inside of the ICM was ongoing. On day 11, the Rauber's layer was focally interrupted and adjacent underlying ICM cells formed tight junctions. The hypoblast, which formed a thin confluent cell layer, was separated from the ICM and the tropho-blast by intercellular matrix. The embryos were ovoid to tubular and displayed a confluent hypoblast on day 14. The epiblast was inserted into the trophoblast epithelium and tight junctions and desmosomes were present between adjacent epiblast cells as well as between peripheral epiblast and trophoblast cells. In some embryos, the epiblast was more or less covered by foldings of trophoblast in the process of forming the amniotic cavity. Cytokeratin 8 was localized to the trophoblast and the hypoblast underlying the epiblast; alpha-1-fetoprotein was localized to most hypoblast cells underlying the trophoblast; and vimentin was localized to most epiblast cells. On day 21, the smallest embryos displayed a primitive streak and formation of the neural groove, whereas the largest embryos presented a neural tube, up to 14 somites and allantois development. These embryos depicted the gradual formation of the endoderm, mesoderm and ectoderm as well as differentiation of paraxial, intermediate and lateral plate mesoderm. Cytokeratin 8 was localized to the trophoblast, the hypoblast and the surface and neural ectoderm; and alpha-1-fetoprotein was localized to the hypoblast, but not the definitive endoderm, the intensity increasing with development. Vimentin was initially localized to some, but not all, cells positioned particularly in the ventral region of the primitive streak, to presumptive definitive endoderm cells inserted into the hypoblast, and to mesoderm. In conclusion, within 2 weeks of hatching, bovine embryos complete formation of the hypoblast and the epiblast, establishment of the amniotic cavity, ingression of epiblast cells for primitive streak formation, involution of cells through the node and the streak for endoderm and mesoderm fomation, neurulation and differentiation of the mesoderm. The recruitment of cells from the epiblast to form the primitive streak as well as the endoderm and mesoderm is associated with expression of the intermediate filament vimentin.

scholarly journals Embryonic lethality in mice lacking Trim59 due to impaired gastrulation development

2017 ◽  
Author(s):  
Xiaomin Su ◽  
Chenglei Wu ◽  
Xiaoying Ye ◽  
Ming Zeng ◽  
Zhujun Zhang ◽  
...  
Keyword(s):  
Embryo Development ◽  
Actin Polymerization ◽  
Critical Role ◽  
Cell Mass ◽  
Blastocyst Stage ◽  
Early Embryo ◽  
Germ Layer ◽  
Layer Formation ◽  
Early Embryo Development ◽  
Germ Layer Formation

ABSTRACTTRIM family members have been implicated in a variety of biological processes such as differentiation and development. We here found that Trim59 plays a critical role in early embryo development from blastocyst stage to gastrula. There existed delayed development and empty yolk sacs from embryonic day (E) 8.5 inTrim59-/- embryos. No viableTrim59-/- embryos were observed beyond E9.5. Trim59 deficiency affected primary germ layer formation at the beginning of gastrulation. InTrim59-/- embryos at E6.5 and E7.5, the expression of primary germ layer formation associated genes includingBrachyury,lefty2,Cer1,Otx2,Wnt3andBMP4was reduced. Homozygous mutant embryonic epiblast was contracted and the mesoderm was absent. Trim59 could interact with actin and myosin associated proteins. Trim59 deficiency disturbed F-actin polymerization during inner cell mass differentiation. Trim59 mediated polymerization of F-actin was via WASH K63-linked ubiquitination. Thus, Trim59 may be a critical regulator for early embryo development from blastocyst stage to gastrula through modulating F-actin assembly.

Ultrastructural studies of the mouse blastocyst substages

Development ◽  
1974 ◽  
Vol 32 (3) ◽  
pp. 675-695
Author(s):  
Mary Nadijcka ◽  
Nina Hillman
Keyword(s):  
Tight Junctions ◽  
Inner Cell Mass ◽  
Structural Characteristics ◽  
Cell Mass ◽  
Cell Types ◽  
Blastocyst Stage ◽  
Basal Region ◽  
Trophoblast Cells ◽  
Mouse Blastocyst ◽  
Ultrastructural Studies

The mouse blastocyst stage covers approximately 2 days. During this period, embryonic development advances through four ultrastructurally distinct substages. Specific ultra-structural characteristics, such as changes in cell shape and/or the distribution of intracellular organelles, may be used to characterize the various cell types from each other at each substage (e.g. trophoblast from inner cell mass cells), as well as to distinguish the same cells from each other at different substages (e.g. substage 1 abembryonic trophoblast cells from substage 2 abembryonic trophoblast cells). A distinguishing characteristic of these blastocyst substages are the membrane contacts (tight junctions, desmosomes, focal tight junctions) between cells. The apical surfaces of adjacent trophoblast cells, from the time of cavity formation until the initial stage of implantation, are connected by a tight junction and a desmosome. The basal region of the apposed trophoblast membranes, however, vary both in their spatial interrelationship with each other and in their defined cellular contacts. Likewise, the cell contacts between the inner cell mass cells, and between these cells and the embryonic trophoblast cells, are distinctive for each blastocyst substage.

A chicken caudal homologue, CHox-cad, is expressed in the epiblast with posterior localization and in the early endodermal lineage

Development ◽  
1991 ◽  
Vol 112 (1) ◽  
pp. 207-219 ◽  
Author(s):  
A. Frumkin ◽  
Z. Rangini ◽  
A. Ben-Yehuda ◽  
Y. Gruenbaum ◽  
A. Fainsod
Keyword(s):  
Amino Acids ◽  
Sequence Analysis ◽  
Cdna Clone ◽  
Homeobox Gene ◽  
Primitive Streak ◽  
Definitive Endoderm ◽  
Germ Layer ◽  
Translation Product ◽  
Epithelial Lining ◽  
Chicken Development

CHox-cad is a chicken homeobox gene whose homeodomain is homologous to the Drosophila caudal and the murine Cdx1 genes. Based on sequence analysis of a 2.5 kb CHox-cad cDNA clone, we deduced that the primary translation product consists of 248 amino acids. Comparison between the cDNA and genomic clones revealed the presence of an intron within the CHox-cad homeodomain between amino acids 44 and 45. The onset of CHox-cad transcription correlates temporarily with the beginning of gastrulation. During primitive streak stages CHox-cad exhibits a caudally localized pattern of expression restricted to the epiblast and the primitive streak. At these stages, CHox-cad transcripts can also be detected in the definitive endoderm cells. Later in embryogenesis CHox-cad is expressed in the epithelial lining of the embryonic gut and yolk sac. After four days of chicken development, no CHox-cad transcripts could be detected. The early CHox-cad posterior expression in the germ layer undergoing gastrulation and its continuous expression in the early endodermal lineage raise the possibility of CHox-cad involvement in the establishment of the definitive endoderm.

Clonal analysis of epiblast fate during germ layer formation in the mouse embryo

Development ◽  
1991 ◽  
Vol 113 (3) ◽  
pp. 891-911 ◽  
Author(s):  
K.A. Lawson ◽  
J.J. Meneses ◽  
R.A. Pedersen
Keyword(s):  
Single Cells ◽  
Primitive Streak ◽  
Clonal Analysis ◽  
Neural Plate ◽  
Embryonic Axis ◽  
Population Doubling ◽  
Germ Layer ◽  
Layer Formation ◽  
Fate Map ◽  
Germ Layer Formation

The fate of cells in the epiblast at prestreak and early primitive streak stages has been studied by injecting horseradish peroxidase (HRP) into single cells in situ of 6.7-day mouse embryos and identifying the labelled descendants at midstreak to neural plate stages after one day of culture. Ectoderm was composed of descendants of epiblast progenitors that had been located in the embryonic axis anterior to the primitive streak. Embryonic mesoderm was derived from all areas of the epiblast except the distal tip and the adjacent region anterior to it: the most anterior mesoderm cells originated posteriorly, traversing the primitive streak early; labelled cells in the posterior part of the streak at the neural plate stage were derived from extreme anterior axial and paraxial epiblast progenitors; head process cells were derived from epiblast at or near the anterior end of the primitive streak. Endoderm descendants were most frequently derived from a region that included, but extended beyond, the region producing the head process: descendants of epiblast were present in endoderm by the midstreak stage, as well as at later stages. Yolk sac and amnion mesoderm developed from posterolateral and posterior epiblast. The resulting fate map is essentially the same as those of the chick and urodele and indicates that, despite geometrical differences, topological fate relationships are conserved among these vertebrates. Clonal descendants were not necessarily confined to a single germ layer or to extraembryonic mesoderm, indicating that these lineages are not separated at the beginning of gastrulation. The embryonic axis lengthened up to the neural plate stage by (1) elongation of the primitive streak through progressive incorporation of the expanding lateral and initially more anterior regions of epiblast and, (2) expansion of the region of epiblast immediately cranial to the anterior end of the primitive streak. The population doubling time of labelled cells was 7.5 h; a calculated 43% were in, or had completed, a 4th cell cycle, and no statistically significant regional differences in the number of descendants were found. This clonal analysis also showed that (1) growth in the epiblast was noncoherent and in most regions anisotropic and directed towards the primitive streak and (2) the midline did not act as a barrier to clonal spread, either in the epiblast in the anterior half of the axis or in the primitive streak. These results taken together with the fate map indicate that, while individual cells in the epiblast sheet behave independently with respect to their neighbours, morphogenetic movement during germ layer formation is coordinated in the population as a whole.

Ratio and number of inner cell mass and trophoblast cells of in vitro and in vivo produced porcine embryos

1995 ◽  
Vol 43 (1) ◽  
pp. 304 ◽  
Author(s):  
D. Rath ◽  
H. Niemann ◽  
T. Tao ◽  
M. Boerjan
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Trophoblast Cells

Studies on self-differentiating and induction capacities of Hensen's node using intracoelomic grafting technique

Development ◽  
1972 ◽  
Vol 28 (3) ◽  
pp. 547-558
Author(s):  
J. R. Viswanath ◽  
Leela Mulherkar
Keyword(s):  
Chick Embryo ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Germ Layer ◽  
Grafting Technique ◽  
Definite Combination

Living Hensen's node of the definitive primitive streak of chick embryo was prepared into ‘sandwiches’ with the competent ectoderm and the sandwich grafts were transplated into the 2·5 day chick embryo using the intracoelomic grafting technique of Hamburger. One hundred and twenty-four grafts were prepared and transplanted intracoelomically, 28 grafts were lost due to the death of the host embryos, 63 grafts did not differentiate at all, but 33 well-defined grafts were recovered, after cultivating the transplanted hosts for 12–14 days. All kinds of tissues from feather germs to neural tissue were found to have differentiated in the grafts. The more frequently occurring tissues were feather germs, epidermal vesicle, neural tissue, kidney and muscle. Other differentiations were the cartilage notochord and gut. No definite combination pattern has emerged from the tissues. But when the tissues were traced to their germ-layer derivation, 22 of them belonged to the mesodermal complex, 11 to the ectodermal complex and 8 to the endodermal complex. In the light of the above results, the probable existence of a mesodermal factor and an ectodermal factor independently responsible for the respective differentiations, as also the competence of the ectoderm, is discussed.

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