At what stage of development does the somitic mesoblast invaginate into the primitive streak of chick embryo?

1975 ◽  
Vol 31 (5) ◽  
pp. 584-585 ◽  
Author(s):  
J. Gallera
Keyword(s):  
Chick Embryo ◽  
Primitive Streak ◽  
Stage Of Development

Labelling of basement membrane constituents in the living chick embryo during gastrulation

Development ◽  
1984 ◽  
Vol 79 (1) ◽  
pp. 113-123
Author(s):  
Esmond J. Sanders
Keyword(s):  
Chick Embryo ◽  
Basement Membrane ◽  
Concanavalin A ◽  
Primitive Streak ◽  
Basal Surface ◽  
Stage Of Development ◽  
Pass Through ◽  
The Relationship

The basement membrane of the living chick embryo epiblast has been labelled with ultrastructural markers in order to study the movement and turnover of this structure during gastrulation. Two problems were addressed in these experiments. Firstly, to what extent does the basement membrane move medially with the epiblast during morphogenesis? Secondly, what is the relationship to the basement membrane of the so-called interstitial bodies? The ultrastructural markers used were concanavalin A conjugated to ferritin and fibronectin antibodies conjugated to peroxidase. Embryos were cultured using the technique of New, and the label was applied to the periphery of the basal surface of the epiblast through a hole in the endoblast at the early primitive streak stage of development. The embryos were then allowed to develop to the full primitive streak stage in the presence of the label. When the position of the label was determined after incubation, it was found to have accumulated in large amounts at the edge of the primitive streak at the point where the basement membrane is disrupted. This indicates that constituents of the basement membrane are transported medially with the epiblast cells and are sloughed off as the latter pass through the primitive streak. This movement of basement membrane constituents is counter to the direction of migration of the underlying mesoderm cells. When embryos are exposed to label for only 1 h, then washed and incubated for a further three hours, the marker was found in the interstitial bodies and not distributed throughout the basement membrane itself. This suggests that the interstitial bodies, which have been implicated in influencing the migration of the mesoderm cells, are turnover products of the basement membrane to which they are attached.

Ultrastructural immunocytochemical localization of fibronectin in the early chick embryo

Development ◽  
1982 ◽  
Vol 71 (1) ◽  
pp. 155-170
Author(s):  
E. J. Sanders
Keyword(s):  
Chick Embryo ◽  
Basal Lamina ◽  
Regional Differences ◽  
Developmental Stages ◽  
Primitive Streak ◽  
Extracellular Material ◽  
Cell Surfaces ◽  
Mesoderm Cell ◽  
Stage Of Development ◽  
Primary Location

Fibronectin was localized using peroxidase and biotin-avidin-ferritin techniques in developmental stages of the chick embryo from laying to primitive streak formation. The primary location of fibronectin at all stages examined was the basal lamina of the epiblast and its associated extracellular material. The remaining tissues showed little or no immunochemical deposit. At the primitive streak stage of development there were some regional differences in the density of the deposit on the basal lamina. Closely adjacent to the primitive streak, where the basal lamina is fragmentary, deposit was sparse or absent. In this, and other regions, mesoderm cell surfaces did not stain except where they closely approached the stained basal lamina or interstitial bodies. Staining was variable in the basal lamina anterior to the primitive streak, but in a number of cases particularly heavy deposit was noted overlying the crescent of late hypoblast. This area seemed to correspond with the anterior fibronectin- rich band reported by others using immunofluorescence localization.

Identification of a novel growth factor with transforming activity secreted by individual chick embryos

Development ◽  
1990 ◽  
Vol 109 (4) ◽  
pp. 905-910 ◽  
Author(s):  
J. Smith ◽  
J.C. McLachlan
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Chick Embryo ◽  
Primitive Streak ◽  
Soft Agar ◽  
Heat Stable ◽  
Stage Of Development ◽  
Transforming Activity ◽  
Embryo Tissue ◽  
Differential Responsiveness

Previously we have developed a microassay for anchorage independent growth (AIG) of fibroblasts in soft agar, which can detect very small quantities of transforming growth factors (TGFs). Using this assay, we have shown that small pieces of dissected chick embryo tissue will stimulate AIG of both NR6 and NRK 49f cells, and that this property can be used to map production of growth factors with transforming activity in individual early embryos. We now show that this activity can be transferred to conditioned medium (CM) prepared using chick embryo tissue. Using two cell lines with differential responsiveness to TGFs, and by coincubating normal and heat-treated CM with trypsin, Con-A and neutralising antibodies, we show that CM contains at least two different growth factors with transforming activity. One of these is heat-stable, and stimulates colony formation in NRK 49f cells in the presence of EGF, but not in its absence. This activity corresponds to a TGF beta-like molecule. The other component is a heat-labile glycoprotein, which has TGF alpha-like properties, but does not appear to behave like known TGFs with these properties. It therefore appears to be a novel growth factor. Both activities are present from the intermediate primitive streak stage of development.

Cell proliferation in the gastrulating chick embryo: a study using BrdU incorporation and PCNA localization

Development ◽  
1993 ◽  
Vol 118 (2) ◽  
pp. 389-399 ◽  
Author(s):  
E.J. Sanders ◽  
M. Varedi ◽  
A.S. French
Keyword(s):  
Cell Proliferation ◽  
Chick Embryo ◽  
Cell Density ◽  
Generation Time ◽  
Primitive Streak ◽  
S Phase ◽  
Nuclear Antigen ◽  
Brdu Incorporation ◽  
Similar Proportion ◽  
Differential Growth

Cell proliferation in the gastrulating chick embryo was assessed using two independent techniques which mark cells in S phase of the mitotic cycle: nuclear incorporation of bromodeoxyuridine (BrdU) detected immunocytochemically and immunolocalization of proliferating cell nuclear antigen (PCNA). Computer-reconstructed maps were produced showing the distribution of labelled nuclei in the primitive streak and the cell layers. These distributions were also normalized to take into account regional differences in cell density across the embryo. Results from a 2 hour pulse of BrdU indicated that although cells at caudal levels of the primitive streak showed the highest incorporation, this region showed a similar proportion of labelled cells to the surrounding caudal regions of the epiblast and mesoderm when normalized for cell density. The entire caudal third of the embryo showed the highest proportion of cells in S phase. Cells of Hensen's node showed a relatively low rate of incorporation and, although the chordamesoderm cells showed many labelled nuclei, this appeared to be a reflection of a high cell density in this region. Combining this result with results from a 4 hour pulse of BrdU permitted mapping of cell generation time across the entire embryo. Generation times ranged from a low value of approximately 2 hours at caudal levels of both the epiblast and mesoderm, to an upper value of approximately 10 hours in the rostral regions of the primitive streak, in the mid-lateral levels of the epiblast and in the chordamesoderm rostral to Hensen's node. Cells at caudal regions of the primitive streak showed a generation time of approximately 5 hours. Taking into account that cells are generally considered to be continuously moving through the primitive streak, we conclude that cell division, as judged by generation time, is greatly reduced during transit through this region, despite the presence there of cells in S phase and M phase. Immunocytochemical localization of PCNA-positive nuclei gave generally similar distributions to those obtained with BrdU incorporation, confirming that this endogenous molecule is a useful S-phase marker during early embryogenesis. Mid-levels and caudal levels of the primitive streak showed the highest numbers of positive nuclei, and the highest proportion of labelling after cell density was accounted for. As with BrdU incorporation, the highest proportions of PCNA-positive nuclei were found towards the caudal regions of the epiblast and mesoderm. These results suggest that the differential growth of the caudal region of the embryo at this time is a direct consequence of elevated levels of cell proliferation in this region.(ABSTRACT TRUNCATED AT 400 WORDS)

Primordial germ cells in normal and transected duck blastoderms

Development ◽  
1968 ◽  
Vol 20 (3) ◽  
pp. 247-260
Author(s):  
Teresa Rogulska
Keyword(s):  
Chick Embryo ◽  
Blood Vessels ◽  
Germ Cells ◽  
Anterior Part ◽  
Primordial Germ Cells ◽  
Primitive Streak ◽  
Experimental Investigations ◽  
Suggestive Evidence ◽  
Area Pellucida

Suggestive evidence for the extragonadal origin of germ cells in birds was first presented by Swift (1914), who described primordial germ cells in the chick embryo at as early a stage as the primitive streak. According to Swift, primordial germ cells are originally located extra-embryonically in the anterior part of the blastoderm and occupy a crescent-shaped region (‘germinal crescent’) on the boundary between area opaca and area pellucida. Swift also found that primordial germ cells later enter into the blood vessels, circulate together with the blood throughout the whole blastoderm and finally penetrate into the genital ridges, where they become definitive germ cells. Swift's views have been confirmed in numerous descriptive and experimental investigations. Among the latter, the publications of Willier (1937), Simon (1960) and Dubois (1964a, b, 1965a, b, 1966) merit special attention. Dubois finally proved that the genital ridges exert a strong chemotactic influence on the primordial germ cells.

Changes in the transferrin requirement of cultured chick embryo mesoderm cells during early differentiation

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 81-93
Author(s):  
E. J. Sanders
Keyword(s):  
Chick Embryo ◽  
Type I Collagen ◽  
Specific Effect ◽  
Primitive Streak ◽  
Cellular Adhesion ◽  
Type I ◽  
Surface Binding ◽  
Surface Receptors ◽  
Early Differentiation ◽  
Species Specific

Mesodermal tissue from the chick embryo at various stages of early differentiation was cultured in hydrated gels of type I collagen in the presence and absence of transferrin. Primary mesoderm explants from primitive-streak-stage embryos responded to the presence of avian transferrin by significantly improved outgrowth which appeared to be related to the ability of the cells to attach to, and migrate in, the collagen. No evidence was obtained which suggested that this observation was dependent on increased cell proliferation. This outgrowth enhancement was not duplicated by transferrin of human origin. The avian transferrin did not produce this effect on cells cultured on plastic substrata, suggesting that the species-specific effect involves modulation by the extracellular matrix. Mesoderm explants from somite stages of development showed no increase in outgrowth in the presence of either avian or human transferrin as judged by counting the number of outwandering cells. Ultrastructural immunocytochemistry indicated surface binding of transferrin by cells in the gels, and the presence of endogenous transferrin on the surfaces of mesoderm cells in situ and in their extracellular environment. It is suggested that by binding to cell surface receptors, transferrin may be able to influence the strength of cellular adhesion to collagen and hence the capacity for cell locomotion.

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