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.

scholarly journals Segregating expression domains of two goosecoid genes during the transition from gastrulation to neurulation in chick embryos

Development ◽  
1997 ◽  
Vol 124 (8) ◽  
pp. 1443-1452 ◽  
Author(s):  
L. Lemaire ◽  
T. Roeser ◽  
J.C. Izpisua-Belmonte ◽  
M. Kessel
Keyword(s):  
Posterior Margin ◽  
Anterior Part ◽  
Primitive Streak ◽  
Neural Plate ◽  
Chick Embryos ◽  
Positive Part ◽  
Full Extension ◽  
Isolation And Characterization ◽  
Chick Embryogenesis

We report the isolation and characterization of a chicken gene, GSX, containing a homeobox similar to that of the goosecoid gene. The structure of the GSX gene and the deduced GSX protein are highly related to the previously described goosecoid gene. The two homeodomains are 74% identical. In the first few hours of chick embryogenesis, the expression pattern of GSX is similar to GSC, in the posterior margin of the embryo and the young primitive streak. Later during gastrulation, expression of the two genes segregate. GSC is expressed in the anterior part of the primitive streak, then in the node, and finally in the pre-chordal plate. GSX is expressed in the primitive streak excluding the node, and then demarcating the early neural plate around the anterior streak and overlying the pre-chordal plate. We demonstrate that the GSX-positive part of the primitive streak induces gastrulation, while the GSC-expressing part induces neurulation. After full extension of the streak, the fate of cells now characterized by GSX is to undergo neurulation, while those expressing GSC undergo gastrulation. We discuss the effect of a duplicated basic goosecoid identity for the generation of a chordate nervous system in ontogeny and phylogeny.

Experiments on Embryonic Induction

1934 ◽  
Vol 11 (3) ◽  
pp. 224-227 ◽  
Author(s):  
C. H. WADDINGTON
Keyword(s):  
Embryonic Development ◽  
Primitive Streak ◽  
Neural Plate ◽  
Species Specificity ◽  
Embryonic Induction ◽  
Embryonic Shield

The communication describes two cases of induction by pieces of the chick primitive streak grafted into the embryonic shield of the rabbit (7½ days after copulation, long primitive streak stage) and discusses the technical difficulties raised by such experiments. The results show that the ectoderm of the rabbit at this stage possesses the capacity of reacting to an inducing stimulus by the formation of neural plate (i.e. is "competent" (Waddington, 1932) to form neural plate), and thus make it probable that the embryonic development of the mammals is influenced by factors similar to those which have become familiar in the Amphibia and birds. They are also a demonstration of the lack of species specificity of the inducing agents involved in embryonic organisers.

Regional developmental capacities of the rat embryonic endoderm at the head-fold stage

Development ◽  
1974 ◽  
Vol 32 (2) ◽  
pp. 461-467
Author(s):  
A. Švajger ◽  
B. Levak-Švajger
Keyword(s):  
Adult Male ◽  
Primitive Streak ◽  
Neural Plate ◽  
Male Rats ◽  
Germ Layers ◽  
Kidney Capsule ◽  
Gut Endoderm ◽  
Derivatives Of

Three areas, composed of all three germ layers, were isolated from Fischer strain rat embryonic shields at the head-fold stage, and grafted separately under the kidney capsule of adult male rats of the same strain. The areas were from the neural plate, Hensen's node and the primitive streak. The resulting teratomas were examined histologically for the presence of derivatives of the primitive gut. The grafts differed strikingly in their capacity to develop into different segments of the gut. Endoderm underlying the neural plate developed into derivatives of the foregut, while endoderm underlying the primitive streak developed mainly into derivatives of the mid- and hindgut. It was concluded that, at the head-fold stage, the capacities to develop into different segments of the definitive gut are already roughly limited to particular areas of the endoderm.

Is there a ventral neural ridge in chick embryos? Implications for the origin of adenohypophyseal and other APUD cells

Development ◽  
1980 ◽  
Vol 57 (1) ◽  
pp. 71-78
Author(s):  
N. B. Levy ◽  
Ann Andrew ◽  
B. B. Rawdon ◽  
Beverley Kramer
Keyword(s):  
Neural Crest ◽  
Endocrine Cells ◽  
Ventral Surface ◽  
Neural Plate ◽  
Chick Embryos ◽  
Serial Sections ◽  
Apud Cells ◽  
Surface Ectoderm ◽  
Neural Ectoderm ◽  
Thickened Surface

Two- to ten-somite chick embryos were studied in order to ascertain whether, as has been proposed, there exists a ‘ventral neural ridge’ which gives rise to the hypophyseal (Rathke's) pouch. Serial sections and stereo-microscopy were used. The neural ridges arch around the rostral end of the embryo onto the ventral surface of the head, but no evidence was found for their extension to form a ‘ventral neural ridge’ reaching the stomodaeum: in fact a considerable expanse of non-thickened surface ectoderm was seen to separate the ventral portions of the neural ridges from the stomodaeum. The thickening of neural ectoderm which does appear on the ventral surface of the head results from apposition and fusion of the opposite neural ridges flanking the neural plate and thus the tip of the anterior neuropore - the classically accepted mode of closure of the neuropore. These findings are in accord with the generally accepted concept of the origin of thehypophyseal pouch rather than with its derivation from a ‘ventral neural ridge’. No sign of neural crest formation was encountered ventrally; this observation excludes the possibility that endocrine cells of the APUD series could originate from neural crest in this region.

scholarly journals Experiments on the Development of the Head of the Chick Embryo

1936 ◽  
Vol 13 (2) ◽  
pp. 219-236
Author(s):  
C. H. WADDINGTON ◽  
A. COHEN
Keyword(s):  
Thin Sheet ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Neural Plate ◽  
Head Region ◽  
Process Stage ◽  
Optic Vesicles ◽  
Lens Formation ◽  
Embryonic Ectoderm

1. Experiments were made on the development of the head of chicken embryos cultivated in vitro. 2. Defects in the presumptive head region of primitive streak embryos are regulated completely if the wound fills up before the histogenesis of neural tissue begins in the head-process stage. Different methods by which the hole is filled are described. 3. No repair occurs in the head-process and head-fold stages, and in this period two masses of neural tissue cannot heal together. 4. Median defects, even if repaired as regards neural tissue, cause a failure of the ventral closure of the foregut. The lateral evaginations of the gut develop typically in atypical situations. The headfold may break through and join up with the endoderm in such a way that the gut acquires an anterior opening. 5. The paired heart rudiments may develop separately. The separate vesicles begin to contract at a time appropriate to the development of the embryo as a whole. The two hearts are mirror images, the left one having the normal curvature, but the embryos do not survive long enough for the hearts to acquire a very definite shape. 6. The forebrain has a considerable capacity for repair in the early somite stages (five to twenty-five somites). One-half of the forebrain can remodel itself into a complete forebrain. In some cases the neural plate and epidermis grow together over the wound, in others the epidermis and mesenchyme make the first covering, leaving a space along the inside of which the neural tissue grows. The neural tissue may become a very thin sheet. 7. The repaired forebrain may induce the formation of a nasal placode from the non-presumptive nasal epidermis which covers the wound. 8. If the optic vesicle is entirely removed, a new one is not formed, but parts of the vesicle can regulate to complete eye-cups, either when still attached to the forebrain or after being isolated in the extra-embryonic regions of another embryo. 9. Injured optic vesicles induce lenses from the non-presumptive epidermis which grows over the wound. Transplanted optic neural tissue from embryos of about five somites induces the formation of lentoids from extra-embryonic ectoderm, but only in a small proportion of cases. 10. The presumptive lens epidermis can produce a slight thickening even when contact with the optic cup is prevented. 11. The significance of periods of minimum regulatory power for the concept of determination is discussed. 12. The data concerning lens formation are discussed in terms of the field concept.

The Effect of Chloroacetophenone on the Inducing Capacity of Hensen's Node

Development ◽  
1962 ◽  
Vol 10 (3) ◽  
pp. 383-388
Author(s):  
M. S. Lakshmi
Keyword(s):  
Organizer Region ◽  
High Capacity ◽  
Primitive Streak ◽  
Chick Embryos

In a previous paper (Lakshmi, 1962) the effects of ω-chloroacetophenone (CAP), which is an irreversible —SH inhibitor, on the morphogenesis of chick embryos cultured in vitro were reported. Brachet (1950) suggested that the —SH-containing proteins might be active in induction. Rapkine & Brachet (1951) studied the effect of monoiodoacetate on the amphibian organizer and observed that the organizer region retained a high capacity for induction despite treatment with the inhibitor. The action of monoiodoacetate is reversible, hence it was felt desirable to investigate the action of CAP on the living organiser of chick, namely Hensen's node. Chick embryos at the primitive-streak stage were explanted in vitro by New's (1955) technique. These were treated with 0·0005 M CAP for 15 and 30 minutes, 0·001 M CAP for 15 minutes, and 0·0015 M CAP for 15 minutes. 0·1 ml. of the solution was added to the endodermal surface of the explanted embryos.

The Effect of Chloroacetophenone on Chick Embryos Cultured in vitro

Development ◽  
1962 ◽  
Vol 10 (3) ◽  
pp. 373-382
Author(s):  
M. S. Lakshmi
Keyword(s):  
Xenopus Laevis ◽  
Average Length ◽  
Primitive Streak ◽  
Poultry Farm ◽  
Chick Embryos ◽  
Normal Process ◽  
Strong Emphasis ◽  
The Brain

Brachet's (1950) strong emphasis on the role of —SH-containing proteins in the process of induction has stimulated a study of the interference in the normal process of morphogenesis of chick embryos by chloroacetophenone, which has been described by Beatty (1951) as a specific and irreversible —SH inhibitor. He studied the effect of chloroacetophenone on the development of embryos of Rana and Triturus employing different concentrations. Deuchar (1957) also studied the action of the same chemical on the embryos of Xenopus laevis and has recorded abnormalities mainly in the brain and the eye. In the present work ω-chloroacetophenone (CAP) commercially known as phenacyl chloride (ω—C6H5.CO.CH2Cl) was employed. The sample used was a B.D.H. product. Fresh fertilized hens' eggs brought from a local poultry farm were incubated at 37·5° C. for 16 to 18 hours to obtain definitive primitive-streak stages (range of length from 1·75 mm. to 2 mm.) or for about 22 hours to obtain head-process stages (average length of the head process alone 0·56 mm.).

The marginal zone and its contribution to the hypoblast and primitive streak of the chick embryo

Development ◽  
1990 ◽  
Vol 109 (3) ◽  
pp. 667-682 ◽  
Author(s):  
C.D. Stern
Keyword(s):  
Chick Embryo ◽  
Marginal Zone ◽  
Primitive Streak ◽  
Time Lapse ◽  
Study Time ◽  
Fate Mapping ◽  
Deep Part ◽  
Germ Layers ◽  
Gut Endoderm ◽  
Transplantation Experiments

The marginal zone of the chick embryo has been shown to play an important role in the formation of the hypoblast and of the primitive streak. In this study, time-lapse filming, fate mapping, ablation and transplantation experiments were combined to study its contribution to these structures. It was found that the deep (endodermal) portion of the posterior marginal zone contributes to the hypoblast and to the junctional endoblast, while the epiblast portion of the same region contributes to the epiblast of the primitive streak and to the definitive (gut) endoderm derived from it. Within the deep part of the posterior marginal zone, a subpopulation of HNK-1-positive cells contributes to the hypoblast. Removal of the deep part of the marginal zone prevents regeneration of the hypoblast but not the formation of a primitive streak. Removal of both layers of the marginal zone leads to a primitive streak of abnormal morphology but mesendodermal cells nevertheless differentiate. These results show that the two main properties of the posterior marginal zone (contributing to the hypoblast and controlling the site of primitive streak formation) are separable, and reside in different germ layers. This conclusion does not support the idea that the influence of the posterior marginal zone on the development of axial structures is due to it being the source of secondary hypoblast cells.

The spatial and temporal dynamics of Sax1 (CHox3) homeobox gene expression in the chick's spinal cord

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 1817-1828 ◽  
Author(s):  
P. Spann ◽  
M. Ginsburg ◽  
Z. Rangini ◽  
A. Fainsod ◽  
H. Eyal-Giladi ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Homeobox Gene ◽  
Primitive Streak ◽  
Neural Plate ◽  
Transverse Plane ◽  
Posterior Border ◽  
Anterior Border ◽  
Spatial And Temporal Dynamics ◽  
Specific Localization

Sax1 (previously CHox3) is a chicken homeobox gene belonging to the same homeobox gene family as the Drosophila NK1 and the honeybee HHO genes. Sax1 transcripts are present from stage 2 H&H until at least 5 days of embryonic development. However, specific localization of Sax1 transcripts could not be detected by in situ hybridization prior to stage 8-, when Sax1 transcripts are specifically localized in the neural plate, posterior to the hindbrain. From stages 8- to 15 H&H, Sax1 continues to be expressed only in the spinal part of the neural plate. The anterior border of Sax1 expression was found to be always in the transverse plane separating the youngest somite from the yet unsegmented mesodermal plate and to regress with similar dynamics to that of the segregation of the somites from the mesodermal plate. The posterior border of Sax1 expression coincides with the posterior end of the neural plate. In order to study a possible regulation of Sax1 expression by its neighboring tissues, several embryonic manipulation experiments were performed. These manipulations included: removal of somites, mesodermal plate or notochord and transplantation of a young ectopic notochord in the vicinity of the neural plate or transplantation of neural plate sections into the extraembryonic area. The results of these experiments revealed that the induction of the neural plate by the mesoderm has already occurred in full primitive streak embryos, after which Sax1 is autonomously regulated within the spinal part of the neural plate.

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