scholarly journals Experiments on Embryonic Induction

1934 ◽  
Vol 11 (3) ◽  
pp. 218-223
Author(s):  
C. H. WADDINGTON
Keyword(s):  
Recent Work ◽  
Primitive Streak ◽  
Chemical Substance ◽  
Boiling Water ◽  
Direct Result ◽  
Embryonic Induction ◽  
Embryonic Axes ◽  
Chick Blastoderm ◽  
Dead Material ◽  
Regional Character

1. Two cases of induction by coagulated organisers in the chick are described. The implants consisted of pieces of chick primitive streak, and previous to implantation they were killed and coagulated by immersion in boiling water. After this treatment they still retained the inducing capacity which they have been previously shown to possess in the live state. 2. Grafts of dead material into the chick blastoderm usually become enveloped in mesenchyme and thus isolated from the host ectoderm. 3. It is argued that, although there may in the normal egg be a gradient of inducing capacity, the inducing factor itself cannot be a gradient as such: and reference is made to the most recent work which shows that the factor is actually a chemical substance. 4. It is pointed out that there is as yet no evidence that dead organisers can determine the regional character of the embryonic axes which they induce, as live organisers can. 5. In one of the specimens described, the induced axis is accompanied by induced notochord. The question is raised as to whether this notochord is the direct result of the inducing stimulus acting on the host ectoderm, or whether the influence of the host's individuation field has played a part in its formation.

scholarly journals Studies on the nature of the amphibian organization centre. I—Chemical properties of the evocator

1935 ◽  
Vol 117 (804) ◽  
pp. 289-310 ◽  
Keyword(s):  
Active Substance ◽  
Chemical Properties ◽  
Egg Laying ◽  
Embryonic Induction ◽  
Soluble Substance ◽  
Animal Kingdom ◽  
Whole Process ◽  
Adult Tissues ◽  
Regional Character ◽  
Organization Centre

During the amphibian egg-laying season of 1933, Needham, Waddington, and Needham (1933, a , b ; 1934) obtained evidence that the activity of the organization centre of the newt gastrula is partly due to the presence of an ether-soluble substance. The active ether extracts were found to be capable of evoking the formation of a neural tube from the competent presumptive epidermis of the gastrula. It seems difficult, however, to suppose that they can determine the regional character of the evoked neural plate, as normal living organizers do, and the active substance is therefore spoken of as the evocator, to emphasize the fact that its functions represent only one part of the whole process of embryonic induction. The presence of the evocator could also be demonstrated in ether extracts of adult newt tissues; and in a research carried out at the same time Holtfreter (1933) showed that the evocator is present in a large number, if not in all, adult tissues from animals belonging to nearly all the groups of the animal kingdom. Holtfreter found that evocation occurred after the implantation of adult tissues which had been killed and treated with various solvents, but he showed that a prolonged extraction with ether tended to lessen, though it did not entirely destroy, the evocating power of the tissue. This result, which so far as it went was confirmatory of Needham, Waddington, and Needham’s work, was, however, denied by Fischer and Wehmeier (1934), who, on repeating the extraction experiments, could confirm the fact that the ether extracts were active, but claimed that the evocating ability of the tissues was not much lessened by the extraction. In a more recent communication (1934, a ) Holtfreter has repeated his extractions, and finds that the activity of the extracted tissue is only slightly lowered. It is very probable, however, that there will be difficulty in extracting the whole of the active ether-soluble substances from a given mass of tissue. There is general agreement that ether extracts contain an active substance.

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 The Behaviour of Grafts of Primitive Streak Beneath the Primitive Streak of the Chick

1937 ◽  
Vol 14 (3) ◽  
pp. 319-334 ◽  
Author(s):  
M. ABERCROMBIE ◽  
C. H. WADDINGTON
Keyword(s):  
Neural Tissue ◽  
Primitive Streak ◽  
Lateral Plate ◽  
Secondary Axis ◽  
Regional Character ◽  
Host Tissues

1. Grafts consisting of pieces of primitive streak from blastoderms in the primitive streak stage were placed under the primitive streak of blastoderms also in this stage. 2. Various effects of the host on the graft are described, particularly the reversal of the antero-posterior orientation of the graft, the alteration of the regional character of the graft so as to conform with the host tissues at the same level, the suppression of differentiation in the posterior end of the primitive streak, and the incorporation of the graft tissues into the host. 3. A considerable number of inductions occurred, since the host axis often apparently shifts to one side of the graft. The inductions are of two kinds, the normal evocation by graft mesoderm, resulting usually in the formation of superfluous neural tissue; and the complementary induction of a normal secondary axis, which it is supposed is most often due to the preliminary induction of a primitive streak in the host. 4. Various effects of the graft on the host occur. In particular the disturbance of the head mesenchyme suggests that foregut diverticula are produced where head mesenchyme joins lateral plate mesothelium.

Mouse Cdx-1 expression during gastrulation

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 191-203 ◽  
Author(s):  
B.I. Meyer ◽  
P. Gruss
Keyword(s):  
Spinal Cord ◽  
Expression Pattern ◽  
Early Development ◽  
Primitive Streak ◽  
Embryonic Axes ◽  
Specific Expression ◽  
Limb Buds ◽  
Process Formation ◽  
Spinal Cord Level ◽  
Anterior Posterior

We describe the expression pattern of the mouse Cdx-1 gene during early development, examined by both RNA and protein analyses. Cdx-1 expression began with the onset of the head process formation (day 7.5) in ectodermal and mesodermal cells of the primitive streak. Expression extended initially to the middle of the prospective hindbrain and subsequently regressed caudad to the spinal cord level by day 9.5. The mesoderm-specific expression was detected in the first somites and could be followed during their differentiation to the myotome of the dorsal somitic edge by day 12. The developing limb buds and the mesonephros exhibited expression up to day 12. No signal could be detected in notochordal cells and cells of the definitive endoderm. Thus, Cdx-1 is expressed during gastrulation when anterior-posterior positional values are established along the embryonic axes. Furthermore, the expression correlates with the formation of segmented tissue in the posterior hindbrain, the spinal cord and structures like the mesonephros.

Alcian blue staining during the formation of mesoblast in the primitive streak stage chick blastoderm

1980 ◽  
Vol 160 (3) ◽  
pp. 361-367 ◽  
Author(s):  
Ch. Vanroelen ◽  
L. Vakaet ◽  
L. Andries
Keyword(s):  
Alcian Blue ◽  
Primitive Streak ◽  
Blue Staining ◽  
Alcian Blue Staining ◽  
Chick Blastoderm

scholarly journals Experiments on Embryonic Induction

1934 ◽  
Vol 11 (3) ◽  
pp. 212-217
Author(s):  
C. H. WADDINGTON
Keyword(s):  
Primitive Streak ◽  
Neural Plate ◽  
Chick Embryos ◽  
Embryonic Induction ◽  
Gut Endoderm

It is shown that the ectoderm of the area opaca of chick embryos of the primitive streak stage can react to primitive streak grafts by the formation of an induced neural plate. The conclusion is drawn that the competence to form neural plate is not conferred on ectoderm by the gut endoderm, which determines the formation of the primitive streak.

Erythroid cell differentiation in unincubated chick blastoderm in culture

Development ◽  
1980 ◽  
Vol 58 (1) ◽  
pp. 209-216
Author(s):  
Nikolas Zagris
Keyword(s):  
Primitive Streak ◽  
Cell Types ◽  
Ventral Side ◽  
Erythroid Cell ◽  
Cell Populations ◽  
Axis Formation ◽  
Yolk Mass ◽  
Chick Blastoderm ◽  
Serum Free ◽  
Erythroid Cell Differentiation

Morphologically distinct erythroid cell types characteristic of the primitive and the definitiveerythroid cell lines, and embryonic and adult haemoglobins are produced when the unin-cubated chick blastoderm is cultured ventral side down on a filter raft to inhibit morphogeneticmovements and subsequent primitive-streak formation mechanically in serum-free minimalessential medium. The primitive and definitive erythroid cell populations appear consecutivelyin culture even though there is no axis formation nor apparent morphogenesis. The informa-tion to produce both the early and late haemoglobins and erythroid cell types is independentof axis formation and of specific extra-embryonic influences, such as progressive inductionexerted by the yolk mass.

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.

Changes in the expression of the carbohydrate epitope HNK-1 associated with mesoderm induction in the chick embryo

Development ◽  
1988 ◽  
Vol 104 (4) ◽  
pp. 643-655 ◽  
Author(s):  
D.R. Canning ◽  
C.D. Stern
Keyword(s):  
Affinity Purification ◽  
Primitive Streak ◽  
Cell Types ◽  
Staining Intensity ◽  
Mesoderm Induction ◽  
Lateral Plate ◽  
Chick Blastoderm ◽  
Western Blots ◽  
Immunohistochemical Studies ◽  
Related Proteins

We report that a monoclonal antibody, HNK-1, identifies specific regions and cell types during primitive streak formation in the chick blastoderm. Immunohistochemical studies show that the cells of the forming hypoblast are HNK-1 positive from the earliest time at which they can be identified. Some cells of the margin of the blastoderm are also positive. The mesoderm cells of the primitive streak stain strongly with the antibody from the time of their initial appearance. In the epiblast, some cells are positive and some negative at pre-primitive-streak stages, but as the primitive streak develops a gradient of staining intensity is seen within the upper layer, increasing towards the primitive streak. At later stages of development, the notochord and the mesenchyme of the headfold are positive, while the rest of the mesoderm (lateral plate) no longer expresses HNK-1 immunoreactivity. This antibody therefore reveals changes associated with mesodermal induction: before induction, it recognizes the ‘inducing’ tissue (the hypoblast) and reveals a mosaic pattern in the responding tissue (the epiblast); after primitive streak formation, the mesoderm of the primitive streak that results from the inductive interactions expresses the epitope strongly. Affinity purification of HNK-1-related proteins in various tissues was carried out, followed by SDS-PAGE to identify them. The hypoblast, mesoderm and epiblast of gastrulating chick embryos have some HNK-1-related proteins in common, while others are unique to specific tissues. Attempts have been made to identify these proteins using Western blots and antibodies known to recognize HNK-1-related molecules, but none of the antibodies used identify the bands unique to any of the tissues studied. We conclude that these proteins may be novel members of the HNK-1/L2 family, and that they may have a role in cell interactions during early development.

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