scholarly journals Studies on the Development of the Foregut in the Chick Blastoderm

Development ◽  
1953 ◽  
Vol 1 (4) ◽  
pp. 369-385
Author(s):  
Ruth Bellairs
Keyword(s):  
Tissue Culture ◽  
Morphological Changes ◽  
Primitive Streak ◽  
Dorsal Side ◽  
Reference Points ◽  
Chick Blastoderm ◽  
Plasma Clot ◽  
Morphogenetic Movements ◽  
General Expansion ◽  
External Reference

The first of this series of papers (Bellairs, 1953) outlined the morphological changes occurring in the endoderm of the chick up to the stage of about ten pairs of somites; it also showed that the presumptive foregut area in the primitive streak stage blastoderm lies around the anterior end of the primitive streak, and at a slightly later stage around the head process. The present paper is concerned with the pattern of morphogenetic movements which occur in the endoderm during the early stages of foregut development. The technique involved the use of carbon marks upon the exposed endoderm of blastoderms grown dorsal side downwards in tissue culture by the watchglass method (Waddington, 1932; Bellairs, 1953). During the period of development investigated an expansion of the blastoderm as a whole took place over the plasma clot; the use of external reference points was therefore essential, although even with such aids it was not always possible to tell whether certain displacements of marked cells were in fact merely the expression of a general expansion or were due to a specific morphogenetic migration.

The Conversion of Yolk into Cytoplasm in the Chick Blastoderm as shown by Electron Microscopy

Development ◽  
1958 ◽  
Vol 6 (1) ◽  
pp. 149-161
Author(s):  
Ruth Bellairs
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Embryonic Development ◽  
Light Microscopy ◽  
Morphological Changes ◽  
Primitive Streak ◽  
Single Stage ◽  
Embryonic Cells ◽  
Chick Blastoderm ◽  
Almost All

In almost all embryos yolk becomes converted into cytoplasm. It has not previously been possible to describe in any detail the morphological changes involved in this process; indeed, when the yolk drops contained within embryonic cells are examined by light microscopy they seem to remain in much the same condition until they are suddenly used up. For this reason they have frequently been considered to be nothing but ‘inert, inactive’ stores of food. By using an electron microscope, however, it has been possible to trace some of the morphological changes which take place in the chick when intra-cellular yolk drops are converted into cytoplasm, and to show that these are not confined to a single stage of embryonic development. Moreover, the discovery of mitochondria within the yolk drops suggests that the yolk drops are not ‘inert’. The following stages have been examined: medium and long primitive streak (as defined by Waddington, 1932, and Abercrombie, 1950), head process, head fold, and 10–16 pairs of somites.

scholarly journals Studies on the Development of the Foregut in the Chick Blastoderm

Development ◽  
1953 ◽  
Vol 1 (2) ◽  
pp. 115-124
Author(s):  
Ruth Bellairs
Keyword(s):  
Morphological Changes ◽  
Primitive Streak ◽  
Serial Sections ◽  
Present Communication ◽  
Chick Blastoderm ◽  
Process Stage ◽  
Early Stages

Little attention has hitherto been paid to the early stages in the development of the foregut in the chick. This paper is the first of a series concerned with an investigation into how it develops during the period between the primitive streak stage and the stage of an embryo with about ten pairs of somites. The term ‘foregut’ refers throughout to the blind diverticulum extending forward into the developing head from the anterior intestinal portal. The present communication opens with a brief consideration of the gross morphological changes which take place; the rest of the paper is concerned with the location in primitive streak and head process stage blastoderms of the presumptive area from which the foregut of the ten somite embryo will develop. The following account has been compiled from the study of serial sections of twenty embryos and from the publications of Duval (1889), Adelmann (1922), and Wetzel (1929).

scholarly journals A Cellular Reaction to Antibody in Tissue Culture Studied with Electron Microscopy

1959 ◽  
Vol 5 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Harrison Latta
Keyword(s):  
Electron Microscopy ◽  
Tissue Culture ◽  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Normal Serum ◽  
Butyl Methacrylate ◽  
Heart Cells ◽  
Plasma Clot ◽  
Outer Nuclear Membrane ◽  
Cell Components

The reaction of embryonic chick heart cells grown in tissue culture to specific guinea pig antiserum has been studied with electron microscopy. Heart fragments from chick embryos were cultured with a plasma clot. After being tested with antiserum or normal serum, they were fixed with buffered osmium tetroxide and embedded in butyl methacrylate before removal from the glass culture chamber. Thin cells found by phase microscopy to have reacted were sectioned in a plane parallel to the glass surface on which they had grown. The results confirm and extend observations made previously while the reactions were occurring. The plasma membrane, like that of the red cell, becomes disrupted or less resistant to trauma following the action of antiserum. The membranes of mitochondria and endoplasmic reticulum vesiculate and swell. Before nuclear shrinkage becomes prominent, the outer nuclear membrane separates over a large portion of the nuclear envelope and forms one or more large swollen blebs. Thus, the outer nuclear membrane shows a reactivity similar to endoplasmic reticulum. It is suggested that the various physical and chemical changes observed to follow the action of antibody and complement on fibroblasts may be explained by osmotic pressure differences between various cell components. Some basic similarities to the action of hemolytic agents on red cells are noted.

Investigation on the origin of the definitive endoderm in the rat embryo

Development ◽  
1974 ◽  
Vol 32 (2) ◽  
pp. 445-459
Author(s):  
B. Levak-Švajger ◽  
A. Švajger
Keyword(s):  
Primitive Streak ◽  
Definitive Endoderm ◽  
Rat Embryo ◽  
Chick Blastoderm ◽  
Germ Layers ◽  
Kidney Capsule ◽  
Rat Embryos ◽  
Endodermal Cells ◽  
Derivatives Of

Single germ layers (or combinations of two of them) were isolated from the primitive streak and the head-fold stage rat embryos and grown for 15 days under the kidney capsule of syngeneic adult animals. The resulting teratomas were examined histologically for the presence of mature tissues, with special emphasis on derivatives of the primitive gut. Ectoderm isolated together with the initial mesodermal wings at the primitive streak stage gave rise to tissue derivatives of all three definitive germ layers. Derivatives of the primitive gut were regularly present in these grafts. At the head-fold stage, isolated ectoderm (including the region of the primitive streak) differentiated into ectodermal and mesodermal derivatives only. Endoderm isolated at the primitive streak stage did not develop when grafted and was always completely resorbed. At the head-fold stage, however, definitive endoderm differentiated into derivatives of the primitive gut if grafted together with adjacent mesoderm. These findings indirectly suggest the migration of prospective endodermal cells from the primitive ectoderm, and therefore a general analogy with the course of events during gastrulation in the chick blastoderm.

scholarly journals G Proteins G12 and G13 Control the Dynamic Turnover of Growth Factor-induced Dorsal Ruffles

2006 ◽  
Vol 281 (43) ◽  
pp. 32660-32667 ◽  
Author(s):  
Dawei Wang ◽  
Ying-cai Tan ◽  
Geri E. Kreitzer ◽  
Yoko Nakai ◽  
Dandan Shan ◽  
...  
Keyword(s):  
Cell Migration ◽  
Growth Factors ◽  
Growth Factor ◽  
G Proteins ◽  
Morphological Changes ◽  
Dorsal Side ◽  
Circular Membrane ◽  
Actin Reorganization ◽  
Cytoskeletal Remodeling ◽  
Growth Factor Treatment

Growth factors induce massive actin cytoskeletal remodeling in cells. These reorganization events underlie various cellular responses such as cell migration and morphological changes. One major form of actin reorganization is the formation and disassembly of dorsal ruffles (also named waves, dorsal rings, or circular ruffles). Dorsal ruffles are involved in physiological functions including cell migration, invasion, macropinocytosis, plasma membrane recycling, and others. Growth factors initiate rapid formation (within 5 min) of circular membrane ruffles, and these ruffles move along the dorsal side of the cells, constrict, close, and eventually disassemble (∼20 min). Considerable attention has been devoted to the mechanism by which growth factors induce the formation of dorsal ruffles. However, little is known of the mechanism by which these ruffles are disassembled. Here we have shown that G proteins G12 and G13 control the rate of disassembly of dorsal ruffles. In Gα12-/-Gα13-/- fibroblast cells, dorsal ruffles induced by growth factor treatment remain visible substantially longer (∼60 min) than in wild-type cells, whereas the rate of formation of these ruffles was the same with or without Gα12 and Gα13. Thus, Gα12/Gα13 critically regulate dorsal ruffle turnover.

A spinal cord fate map in the avian embryo: while regressing, Hensen's node lays down the notochord and floor plate thus joining the spinal cord lateral walls

Development ◽  
1996 ◽  
Vol 122 (9) ◽  
pp. 2599-2610 ◽  
Author(s):  
M. Catala ◽  
M.A. Teillet ◽  
E.M. De Robertis ◽  
M.L. Le Douarin
Keyword(s):  
Spinal Cord ◽  
Primitive Streak ◽  
Floor Plate ◽  
Dorsal Side ◽  
Avian Embryo ◽  
Tail Bud ◽  
Fate Map ◽  
In Ovo ◽  
Somite Stage ◽  
Lateral Walls

The spinal cord of thoracic, lumbar and caudal levels is derived from a region designated as the sinus rhomboidalis in the 6-somite-stage embryo. Using quail/chick grafts performed in ovo, we show the following. (1) The floor plate and notochord derive from a common population of cells, located in Hensen's node, which is equivalent to the chordoneural hinge (CNH) as it was defined at the tail bud stage. (2) The lateral walls and the roof of the neural tube originate caudally and laterally to Hensen's node, during the regression of which the basal plate anlage is bisected by floor plate tissue. (3) Primary and secondary neurulations involve similar morphogenetic movements but, in contrast to primary neurulation, extensive bilateral cell mixing is observed on the dorsal side of the region of secondary neurulation. (4) The posterior midline of the sinus rhomboidalis gives rise to somitic mesoderm and not to spinal cord. Moreover, mesodermal progenitors are spatially arranged along the rest of the primitive streak, more caudal cells giving rise to more lateral embryonic structures. Together with the results reported in our study of tail bud development (Catala, M., Teillet, M.-A. and Le Douarin, N.M. (1995). Mech. Dev. 51, 51–65), these results show that the mechanisms that preside at axial elongation from the 6-somite stage onwards are fundamentally similar during the complete process of neurulation.

The Adhesive Properties and Expansion of the Chick Blastoderm

Development ◽  
1959 ◽  
Vol 7 (2) ◽  
pp. 146-164
Author(s):  
D. A. T. New
Keyword(s):  
Tissue Culture ◽  
Vitelline Membrane ◽  
Cell Surfaces ◽  
Adhesive Properties ◽  
Chick Blastoderm ◽  
Inner Surface

During the first 4 days of incubation the chick blastoderm expands to surround the yolk. Its expansion takes place over the inner surface of the vitelline membrane, and the edge of the blastoderm is firmly attached to this membrane. Little attention has been paid hitherto to the mechanism of this expansion, presumably because it lies outside the embryo proper. But many of the problems involved are of considerable interest, not only as they relate to development within cleidoic eggs, but also in connexion with more general questions affecting expansion of epithelia and the nature of cell surfaces. Blastoderm expansion has many points of similarity with the spreading of epithelia across wounds, and some of the factors involved may prove to be similar to those affecting the radiation of loose sheets of cells in tissue culture.

Echocardiographic determination of valid zero reference levels in supine and lateral positions

1993 ◽  
Vol 2 (1) ◽  
pp. 72-80 ◽  
Author(s):  
LL Kee ◽  
JS Simonson ◽  
NA Stotts ◽  
P Skov ◽  
NB Schiller
Keyword(s):  
Left Atrium ◽  
Supine Position ◽  
Right Atrium ◽  
Reference Point ◽  
Reference Points ◽  
Pressure Measurements ◽  
Proper Position ◽  
External Reference ◽  
External Point ◽  
The Right

BACKGROUND: The phlebostatic axis--the junction of the fourth intercostal space and the midpoint of the anterior-posterior diameter--has been accepted as a reliable external reference point for the mid-right and mid-left atrium. Acceptance of this reference point is based upon research conducted in 1945 that measured venous pressures in the hands of subjects positioned with the head of the bed raised to different levels. The validity of this reference point for intracardiac pressure measurements in supine or laterally positioned patients has not been established. PURPOSE: To determine the validity of the phlebostatic axis in the supine and lateral positions. METHODS: To determine validity in the supine position, we compared the distance from the phlebostatic axis to a fixed external point (the bed surface) and the distance from the right and left atria in the supine position to this same fixed external point. The distances from the right and left atria to the bed surface were determined with echocardiography and were used as the standard for the proper position of external reference points. To determine the validity of the phlebostatic axis in lateral positions, we compared the distances from the right atrium and left atrium to the bed surface in the supine position with those distances in different lateral positions. RESULTS: We analyzed the data of 25 normal, healthy subjects. The study findings show that the phlebostatic axis is a valid reference point for the right atrium, and the phlebostatic axis and midanterior-posterior diameter are valid reference points for the left atrium in the supine position. However, neither is a valid external reference point in the lateral positions. Pressure measurements obtained when patients are in the lateral positions are not accurate. There remains a need to develop valid methods of accurate pressure measurements in various body positions.

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