An experimental analysis of somite segmentation in the chick embryo

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 93-108
Author(s):  
Ruth Bellairs ◽  
Marianne Veini
Keyword(s):  
Carboxylic Acid ◽  
Chick Embryo ◽  
Neural Tube ◽  
Experimental Analysis ◽  
Collagen Fibrils ◽  
Unoperated Control ◽  
Control Side ◽  
Series Of Experiments

In a previous paper it was suggested that collagen fibrils play an important role in the process of somite segmentation. This paper was designed mainly to test that concept. In one series of experiments, embryos were treated with either αα′-dipyridyl or L-azetidine-2-carboxylic acid, which are analogues that interfere with the formation of normal collagen. The reagents led to a reduction in the numbers of somites that formed, as well as to the production of other anomalies such as overall diminution in size and retardation. The older the embryo at the time of treatment, the further posteriorly were the major anomalies located. It is concluded that these results lend some support to the concept. In a second series of experiments an incision was made along one side of the neural tube and notochord to separate it from the segmental plate on one side. The result was that many more somites formed on the unoperated (control) side of the embryo than on the operated side. It is concluded that these results also lend support to the concept; but that they are of interest also in relation to the mechanisms involved in the control of somite numbers. In a third group of experiments, attempts were made to obtain somites in the absence of endoderm. Although this was not possible using surgery, it was achieved by treating the young embryos with u.v. irradiation. It was concluded that the presence of endoderm is not essential for the segmentation of mesoderm.

Scanning electron microscopic study of collagen fibrillogenesis and extracellular compartmentalization in the chick embryo tendon

1986 ◽  
Vol 44 ◽  
pp. 208-209
Author(s):  
Grace C.H. Yang
Keyword(s):  
Chick Embryo ◽  
Extracellular Space ◽  
Fibroblast Cell ◽  
Collagen Fibrils ◽  
Electron Microscopic ◽  
Voltage Electron ◽  
Scanning Electron Microscopic Study ◽  
Microscopic Studies ◽  
And Function

The size and organization of collagen fibrils in the extracellular matrix is an important determinant of tissue structure and function. The synthesis and deposition of collagen involves multiple steps which begin within the cell and continue in the extracellular space. High-voltage electron microscopic studies of the chick embryo cornea and tendon suggested that the extracellular space is compartmentalized by the fibroblasts for the regulation of collagen fibril, bundle, and tissue specific macroaggregate formation. The purpose of this study is to gather direct evidence regarding the association of the fibroblast cell surface with newly formed collagen fibrils, and to define the role of the fibroblast in the control and the precise positioning of collagen fibrils, bundles, and macroaggregates during chick tendon development.

Overexpression of Snail family members highlights their ability to promote chick neural crest formation

Development ◽  
2002 ◽  
Vol 129 (7) ◽  
pp. 1583-1593 ◽  
Author(s):  
Marta G. del Barrio ◽  
M. Angela Nieto
Keyword(s):  
Chick Embryo ◽  
Neural Crest ◽  
Neural Tube ◽  
Family Members ◽  
Ectopic Expression ◽  
Endogenous Gene ◽  
The Family ◽  
Snail Family ◽  
Migratory Cells ◽  
Snail Gene

The Snail gene family of transcription factors plays crucial roles in different morphogenetic processes during the development of vertebrate and invertebrate embryos. In previous studies of function interference for one of the family members, Slug, we showed its involvement and neural crest formation in the chick embryo. Now we have carried out a series of gain-of-function experiments in which we show that Slug overexpression in the neural tube of the chick embryo induces an increase in neural crest production. The analysis of electroporated embryos shows that Slug can induce the expression of rhoB and an increase in the number of HNK-1-positive migratory cells, indicating that it lies upstream of them in the genetic cascade of neural crest development. The increase in neural crest production after Slug overexpression was confined to the cranial region, indicating that the mechanisms of crest induction somehow differ between head and trunk. The expression of the two vertebrate family members, Slug and Snail, is peculiar with respect to the neural crest. Slug is not expressed in the premigratory crest in the mouse, whereas it is expressed in this cell population in the chick and the opposite is true for Snail(Sefton, M., Sánchez, S. and Nieto M. A. (1998) Development125, 3111-3121). This raises the question of whether they can be functionally equivalent. To test this hypothesis both intra- and interspecies, we have performed a series of ectopic expression experiments by electroporating chick and mouse Snail in the chick embryo hindbrain. We observe that both genes elicit the same responses in the neural tube. Our results indicate that they can be functionally equivalent, although the embryos show a higher response to the endogenous gene, chick Slug.

The differing effects of occipital and trunk somites on neural development in the chick embryo

Development ◽  
1987 ◽  
Vol 100 (3) ◽  
pp. 525-533 ◽  
Author(s):  
T.M. Lim ◽  
E.R. Lunn ◽  
R.J. Keynes ◽  
C.D. Stern
Keyword(s):  
Chick Embryo ◽  
Neural Crest ◽  
Neural Tube ◽  
Neural Development ◽  
Osmium Tetroxide ◽  
Local Property ◽  
Sensory Cells ◽  
Base Of The Skull ◽  
Atlas And Axis ◽  
Zinc Iodide

In all higher vertebrate embryos the sensory ganglia of the trunk develop adjacent to the neural tube, in the cranial halves of the somite-derived sclerotomes. It has been known for many years that ganglia do not develop in the most cranial (occipital) sclerotomes, caudal to the first somite. Here we have investigated whether this is due to craniocaudal variation in the neural tube or crest, or to an unusual property of the sclerotomes at occipital levels. Using the monoclonal antibody HNK-1 as a marker for neural crest cells in the chick embryo, we find that the crest does enter the cranial halves of the occipital sclerotomes. Furthermore, staining with zinc iodide/osmium tetroxide shows that some of these crest-derived cells sprout axons within these sclerotomes. By stage 23, however, no dorsal root ganglia are present within the five occipital sclerotomes, as assessed both by haematoxylin/eosin and zinc iodide/osmium tetroxide staining. Moreover, despite this loss of sensory cells, motor axons grow out in these segments, many of them later fasciculating to form the hypoglossal nerve. The sclerotomes remain visible until stages 27/28, when they dissociate to form the base of the skull and the atlas and axis vertebrae. After grafting occipital neural tube from quail donor embryos in place of trunk neural tube in host chick embryos, quail-derived ganglia do develop in the trunk sclerotomes. This shows that the failure of occipital ganglion development is not the result of some fixed local property of the neural crest or neural tube at occipital levels. We therefore suggest that in the chick embryo the cranial halves of the five occipital sclerotomes lack factors essential for normal sensory ganglion development, and that these factors are correspondingly present in all the more caudal sclerotomes.

Effect of colchicine on mitosis in the neural tube of the forty-eight hour chick embryo

1944 ◽  
Vol 90 (1) ◽  
pp. 51-54 ◽  
Author(s):  
T. M. Woodard ◽  
Sarah B. Estes
Keyword(s):  
Chick Embryo ◽  
Neural Tube
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