Extraembryonic Mesoderm

2017 ◽  
Author(s):  
John H. Duffus ◽  
Michael Schwenk ◽  
Douglas M. Templeton
Keyword(s):  
Extraembryonic Mesoderm

Ultrastructural analysis of collagen formation in the developing primate amnion

1990 ◽  
Vol 48 (3) ◽  
pp. 106-107
Author(s):  
Barry F. King ◽  
Grete N. Fry
Keyword(s):  
Golgi Apparatus ◽  
Collagen Fibril ◽  
Fibril Formation ◽  
Amniotic Cavity ◽  
Cytological Evidence ◽  
Mammalian Embryo ◽  
Intracellular Location ◽  
Collagen Formation ◽  
Amniotic Epithelium ◽  
Extraembryonic Mesoderm

The amnion surrounding the mammalian embryo consists of the amniotic epithelium facing the amniotic cavity, a layer of extraembryonic mesoderm bordering the exocoelom and an intervening layer of extracellular matrix (Fig. 1). During gestation the amnion expands remarkably to acommodate the rapidly growing embryo. In this study we have examined the process of collagen fibril formation in the developing amnion of the rhesus monkey between 20 and 60 days of gestation.Most cytological evidence of collagen fibril formation was observed in association with the extraembryonic mesodermal cells rather than the amniotic epithelium. The mesodermal cells h ad abundant cisternae of rough endoplasmic reticulum and a prominent Golgi apparatus. Elongated secretory vacuoles were associated with the Golgi apparatus and often contained parallel aggregates of fine filaments (Fig. 2). In some secretory vacuoles, periodic densities also were observed. Some striated collagen fibrils were observed in an apparent intracellular location in long, membrane-limited compartments (Fig. 3). Still other striated fibrils were observed in dense bodies, presumably lysosomes (Fig. 4).

scholarly journals Circulation-Independent Differentiation Pathway from Extraembryonic Mesoderm toward Hematopoietic Stem Cells via Hemogenic Angioblasts

Cell Reports ◽  
2014 ◽  
Vol 8 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Yosuke Tanaka ◽  
Veronica Sanchez ◽  
Nozomu Takata ◽  
Tomomasa Yokomizo ◽  
Yojiro Yamanaka ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Hematopoietic Stem ◽  
Extraembryonic Mesoderm

Pattern of the insulin-like growth factor II gene expression during early mouse embryogenesis

Development ◽  
1990 ◽  
Vol 110 (1) ◽  
pp. 151-159 ◽  
Author(s):  
J.E. Lee ◽  
J. Pintar ◽  
A. Efstratiadis
Keyword(s):  
Growth Factor ◽  
Immunohistochemical Analysis ◽  
Primitive Streak ◽  
Insulin Like Growth Factor ◽  
Surface Ectoderm ◽  
Factor Ii ◽  
Extraembryonic Mesoderm ◽  
Early Mouse ◽  
Lateral Mesoderm

The mouse insulin-like growth factor II (IGF-II) gene encodes a polypeptide that plays a role in embryonic growth. We have examined the temporal and spatial pattern of expression of this gene in sections of the mouse conceptus between embryonic days 4.0 and 8.5 by in situ hybridization. Abundant IGF-II transcripts were detected in all the trophectodermal derivatives, after implantation. Labeling was then observed in primitive endoderm, but was transient and disappeared after formation of the yolk sac. Expression was next detected in extraembryonic mesoderm at the early primitive streak stage. Labeling in the embryo proper appeared first at the late primitive streak/neural plate stage in lateral mesoderm and in anterior-proximal cells located between the visceral endoderm and the most cranial region of the embryonic ectoderm. The position of the latter cells suggests that their descendants are likely to participate in the formation of the heart and the epithelium of the ventral and lateral walls of the foregut, where intense labeling was observed at the neural fold stage. Hybridization was also detected in cranial mesenchyme, including neural crest cells. The intensity of hybridization signal increased progressively in paraxial (presomitic and somitic) mesoderm, while declining in the ectoplacental cone. The neuroectoderm and surface ectoderm did not exhibit hybridization at any stage. Immunohistochemical analysis indicated co-localization of IGF-II transcripts, translated pre-pro-IGF-II, and the cognate IGF-II/mannose-6-phosphate receptor. These correlations are consistent with the hypothesis that IGF-II has an autocrine function.

scholarly journals Initiation of hematopoiesis and vasculogenesis in murine yolk sac explants

Blood ◽  
1995 ◽  
Vol 86 (1) ◽  
pp. 156-163 ◽  
Author(s):  
J Palis ◽  
KE McGrath ◽  
PD Kingsley
Keyword(s):  
Endothelial Cells ◽  
Network Formation ◽  
Globin Gene ◽  
Primitive Streak ◽  
Yolk Sac ◽  
Vascular Network ◽  
Globin Mrna ◽  
Capillary Networks ◽  
Stage Of Development ◽  
Extraembryonic Mesoderm

The blood islands of the visceral yolk sac (VYS) are the initial sites of hematopoiesis in mammals. We have developed a yolk sac explant culture system to study the process of blood cell and endothelial cell development from extraembryonic mesoderm cells. No benzidine-positive cells or beta H1-globin mRNA expression was detected at the primitive streak or neural plate stage of development (E7.5). However, when isolated E7.5 dissected tissues were cultured for 36 to 72 hours in serum-free medium, hundreds of hemoglobin-producing cells and embryonic globin gene expression were identified in both intact yolk sac and VYS mesoderm explants. Explanted E7.5 extraembryonic mesoderm tissues thus recapitulate in vivo primitive erythropoiesis and do not require the presence of a vascular network or the VYS endoderm. Yolk sac blood islands also contain endothelial cells that arise by vasculogenesis and express flk-1. We detected flk-1 mRNA as early as the primitive streak stage of mouse embryogenesis. Culture of embryo proper and intact VYS explants, which contain both mesoderm and endoderm cells, produced capillary networks and expressed flk-1. In contrast, vascular networks were not seen when VYS mesoderm was cultured alone, although flk-1 expression was similar to that of intact VYS explants. The addition of vascular endothelial growth factor to VYS mesoderm explants did not induce vascular network formation. These results suggest that the VYS endoderm or its extracellular matrix is necessary for the coalescence of developing endothelial cells into capillary networks.

scholarly journals Cloning and developmental expression of Sna, a murine homologue of the Drosophila snail gene

Development ◽  
1992 ◽  
Vol 116 (1) ◽  
pp. 227-237 ◽  
Author(s):  
M.A. Nieto ◽  
M.F. Bennett ◽  
M.G. Sargent ◽  
D.G. Wilkinson
Keyword(s):  
Neural Crest ◽  
Zinc Finger ◽  
In Situ Hybridisation ◽  
Developmental Expression ◽  
Dorsoventral Patterning ◽  
Murine Homologue ◽  
Extraembryonic Mesoderm ◽  
Snail Gene ◽  
Ectoplacental Cone

The genetic analysis of dorsoventral patterning in Drosophila has identified a zinc-finger gene, snail, that is required for mesoderm formation. The cloning and nuclease protection analysis of a Xenopus homologue of this gene has suggested a possible role in the mesoderm of vertebrates. Here, we describe the cloning of a murine homologue of snail, Sna, and in situ hybridisation studies of its developmental expression. Sequence analysis reveals substantial conservation of the second to fifth zinc fingers, but not of the first zinc finger in the Sna gene. Expression occurs in the ectoplacental cone, parietal endoderm, embryonic and extraembryonic mesoderm, in neural crest and in condensing precartilage. Based on the timing and spatial restriction of expression in embryonic mesoderm, we suggest that Sna might be required for the early development of this tissue, as is the case for its Drosophila counterpart. In addition, we propose that Sna might have an analogous role in the development of neural crest. The expression in condensing precartilage indicates that this gene also has a later function in chondrogenesis.

scholarly journals The bicoid-related homeoprotein Ptx1 defines the most anterior domain of the embryo and differentiates posterior from anterior lateral mesoderm

Development ◽  
1997 ◽  
Vol 124 (14) ◽  
pp. 2807-2817 ◽  
Author(s):  
C. Lanctot ◽  
B. Lamolet ◽  
J. Drouin
Keyword(s):  
Olfactory System ◽  
Branchial Arch ◽  
Lateral Plate ◽  
Chick Embryogenesis ◽  
Head Formation ◽  
Extraembryonic Mesoderm ◽  
Lateral Mesoderm ◽  
Foregut Endoderm ◽  
Derivatives Of

Ptx1 is a member of the small bicoid family of homeobox-containing genes; it was isolated as a tissue-restricted transcription factor of the pro-opiomelanocortin gene. Its expression during mouse and chick embryogenesis was determined by in situ hybridization in order to delineate its putative role in development. In the head, Ptx1 expression is first detected in the ectoderm-derived stomodeal epithelium at E8.0. Initially, expression is only present in the stomodeum and in a few cells of the rostroventral foregut endoderm. A day later, Ptx1 mRNA is detected in the epithelium and in a streak of mesenchyme of the first branchial arch, but not in other arches. Ptx1 expression is maintained in all derivatives of these structures, including the epithelia of the tongue, palate, teeth and olfactory system, and in Rathke's pouch. Expression of Ptx1 in craniofacial structures is strikingly complementary to the pattern of goosecoid expression. In addition, Ptx1 is expressed early (E6.8) in posterior and extraembryonic mesoderm, and in structures that derive from these. The restriction of expression to the posterior lateral plate is later evidenced by exclusive labelling of the hindlimb but not forelimb mesenchyme. In the anterior domain of expression, the stomodeum was shown by fate mapping to derive from the anterior neural ridge (ANR) which represents the most anterior domain of the embryo. The concordance between these fate maps and the stomodeal pattern of Ptx1 expression supports the hypothesis that Ptx1 defines a stomodeal ectomere, which lies anteriorly to the neuromeres that have been suggested to constitute units of a segmented plan directing head formation.

MesP1: a novel basic helix-loop-helix protein expressed in the nascent mesodermal cells during mouse gastrulation

Development ◽  
1996 ◽  
Vol 122 (9) ◽  
pp. 2769-2778 ◽  
Author(s):  
Y. Saga ◽  
N. Hata ◽  
S. Kobayashi ◽  
T. Magnuson ◽  
M.F. Seldin ◽  
...  
Keyword(s):  
Germ Cells ◽  
Southern Hybridization ◽  
Primordial Germ Cells ◽  
Primitive Streak ◽  
Subtractive Hybridization ◽  
Hybridization Study ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Deficiency Gene ◽  
Extraembryonic Mesoderm

A subtractive hybridization strategy was used to isolate putative genes involved in the development of mouse primordial germ cells (PGC). Complimentary DNA was amplified on RNA isolated from the base of the allantois where PGC are located in the 7.5 days post coitum (dpc) mouse embryo. It was then subtracted by hybridization with cDNA amplified on RNA of the anterior region where PGC are absent. A novel gene thus isolated is designated as Mesp1 and encodes a possible transcription factor MesP1 containing a basic helix-loop-helix motif. Its earliest expression was observed at the onset of gastrulation, as early as 6.5 dpc, in the nascent mesodermal cells that first ingressed at the end of the primitive streak. These expressing cells in the lateral and extraembryonic mesoderm showed a wing-shaped distribution. Its initial expression was soon down-regulated at 7.5 dpc before the completion of gastrulation, except at the proximal end of the primitive streak which included the extraembryonic mesoderm and the base of allantois. At 8 dpc, the expression at the base of the allantois moved laterally. This distribution between 7.0 and 8.0 dpc was similar to that of PGC detected by the alkaline phosphatase activity. However, the expression of Mesp1 was down-regulated thereafter, when PGC entered in the migration stage. After birth, Mesp1 expression was detected only in mature testes, but in a different isoform from that expressed in the embryo. Mesp1 was mapped to the mid region of chromosome 7, near the mesodermal deficiency gene (mesd). However, a Southern hybridization study clearly showed that Mesp1 was distinctly different from mesd. The amino acid sequence and its expression pattern suggest that MesP1 plays an important role in the development of the nascent mesoderm including PGC.

Primordial germ cells in the mouse embryo during gastrulation

Development ◽  
1990 ◽  
Vol 110 (2) ◽  
pp. 521-528 ◽  
Author(s):  
M. Ginsburg ◽  
M.H. Snow ◽  
A. McLaren
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Primitive Streak ◽  
Cell Types ◽  
Mesodermal Cell ◽  
Alp Activity ◽  
Cluster Area ◽  
Extraembryonic Mesoderm ◽  
Excised Tissue ◽  
Number Of Cells

With the aid of a whole-mount technique, we have detected a small cluster of alkaline phosphatase (ALP)-positive cells in whole mounts of mid-primitive-streak-stage embryos, 7–7 1/4 days post coitum (dpc). Within the cluster, about 8 cells contain a small cytoplasmic spot, intensely stained for ALP activity and possibly associated with an active Golgi complex. The cluster lies just posterior to the definitive primitive streak in the extraembryonic mesoderm, separated from the embryo by the amniotic fold. Towards the end of gastrulation, the number of cells containing the ALP-positive spot rises to between 50 and 80. Thereafter the number of cells in the extraembryonic cluster declines, and similar cells start to be seen in the mesoderm of the primitive streak and then in the endoderm. At 8 dpc, about 125 ALP-stained cells are found, mainly in the hindgut endoderm and also at the base of the allantois, their appearance and location at this stage agreeing closely with previous reports on primordial germ cells (PGCs). Embryos from which the cluster area has been removed at the 7-day stage are devoid of PGCs after culture for 48 h, whereas the excised tissue is rich in PGCs. We argue that the cells in the cluster are indeed primordial germ cells, at a stage significantly earlier than any reported previously. This would indicate that the PGC lineage in the mouse is set aside at least as early as 7 dpc, possibly as one of the first ‘mesodermal’ cell types to emerge, and that its differentiation, as expressed by ALP activity, is gradual.

Interactions between primordial germ cells play a role in their migration in mouse embryos

Development ◽  
1994 ◽  
Vol 120 (1) ◽  
pp. 135-141 ◽  
Author(s):  
M. Gomperts ◽  
M. Garcia-Castro ◽  
C. Wylie ◽  
J. Heasman
Keyword(s):  
Germ Cells ◽  
Primordial Germ Cells ◽  
Primitive Streak ◽  
Carbohydrate Antigen ◽  
Mature Stage ◽  
Conventional View ◽  
Embryonic Antigen ◽  
Hind Gut ◽  
Extraembryonic Mesoderm ◽  
Dorsal Mesentery

Primordial germ cells (PGCs) are the founder cell population of the gametes which form during the sexually mature stage of the life cycle. In the mouse, they arise early in embryogenesis, first becoming visible in the extraembryonic mesoderm, posterior to the primitive streak, at 7.5 days post coitum (d.p.c.). They subsequently become incorporated into the epithelium of the hind gut, from which they emigrate (9.5 d.p.c.) and move first into the dorsal mesentery (10.5 d.p.c.), and then into the genital ridges that lie on the dorsal body wall (11.5 d.p.c.). We have used confocal microscopy to study PGCs stained with an antibody that reacts with a carbohydrate antigen (Stage-Specific Embryonic Antigen-1, SSEA-1) carried on the PGC surface. This allows the study of the whole PGC surface, at different stages of their migration. The appearance of PGCs in tissue sections has given rise to the conventional view that they migrate as individuals, each arriving in turn at the genital ridge. In this paper, we show that PGCs leave the hind gut independently, but then extend long (up to 40 microns) processes, with which they link up to each other to form extensive networks. During the 10.5-11.5 d.p.c. period, these networks of PGCs aggregate into groups of tightly apposed cells in the genital ridges. As this occurs, their processes are lost, and their appearance suggests they are now non-motile. Furthermore, we find that PGCs taken from the dorsal mesentery at 10.5 d.p.c. perform the same sequence of movements in culture.(ABSTRACT TRUNCATED AT 250 WORDS)

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