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Topic: Ectoderm

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In the News (Thu 21 Mar 19)

  Ectodermal Wnt3/beta -catenin signaling is required for the establishment and maintenance of the apical ectodermal ...
in the limb ectoderm (Roelink and Nusse 1991
the dorsal and ventral ectoderm (i.e., the anterior and posterior
Wnt responsiveness in the ectoderm of the limb, we undertook an
www.genesdev.org /cgi/content/full/17/3/394   (7466 words)

 ectoderm on Encyclopedia.com   (Site not responding. Last check: 2007-11-07)
In higher animals, such as those of the phyla Echinodermata and Chordata, a third, middle layer, the mesoderm, is formed between the ectoderm and endoderm during gastrulation, and the process is termed triploblastic development.
In most embryos, differentiation of ectodermal tissue gives rise to epidermis and its specialized structures (scales, feathers, nails, and hair); some exocrine glands (sweat and sebaceous glands); some endocrine glands (the pineal body and the pituitary gland); the nervous system; and the organs of special sense (ear and eye).
In animals of some phyla, such as the Mollusca and Annelida, the fate of particular cells of the embryo is determined in the earliest stages of the fertilized egg and may even be fixed at or before fertilization.
www.encyclopedia.com /html/e1/ectoderm.asp   (431 words)

 The evolution of embryological development
The ectodermal gradients depend on the location of the mouth cells, and when the inner core of cells joins the ectoderm, it picks up the ectodermal gradients, enabling the split that forms in their midst to open up in the direction of the mouth.
Neurons still differentiate from the ectoderm, but the ectoderm from which they differentiate is a region that has separated from the outer skin and rolled itself up as a neural tube which is contained as a unit inside the body.
Ectodermal cells are determined to become part of the neural plate by the effect of the choradmesoderm on them during the process of gastrulation.
www.twow.net /ObjText/OtkCbGeRRS04D.htm   (8435 words)

 Wnt signaling in Xenopus embryos inhibits Bmp4 expression and activates neural development -- Baker et al. 13 (23): ...   (Site not responding. Last check: 2007-11-07)
Ectoderm was removed at blastula stage, and RNA extracted at late neurula stage (20) (A,C) gastrula stage (10.5) (B) or for analysis by RT-PCR.
Aged ectoderm and whole embryos were then double stained by in situ hybridization for the cement gland marker, XAG (red), and the general neural marker, Nrp1 (blue) (A-G) or single stained by in situ hybridization for the hindbrain marker, krox-20 (blue) (H-N).
Ectoderm was injected with 250pg of mWnt8 (A,E,I,M) or 100 pg of noggin (B,F,J,N), aged to stage 10 (A-C), stage 10.5 (E,F,G), stage 12 (I-K), or stage 21 (M-O), and probed with either digoxigenin-labeled Bmp4 (A-L) or digoxigenin-labeled Nrp1 (M-P).
www.genesdev.org /cgi/content/full/13/23/3149   (5924 words)

 Evolutionary Developmental Biology
In the future head the neural ectoderm is specified to form the three major divisions of the brain by the notochord.
Ectoderm from the early neural tube will not respond to inductive influences produced by the hindbrain of late nerulae and ectoderm from beyond neurulation doesn't respond either.
The ectoderm, of course, interacts with the mesoderm to produce the outgrowth of the limb, but transplanting ectoderm from forelimb to hindlimb still leaves a hindlimb, and vice versa.
www.leeds.ac.uk /chb/lectures/edb12.html   (3132 words)

 Sonic hedgehog
The limb is composed of tissue from the somatic part of the lateral plate mesoderm and the somites; it is surrounded by epithelial tissue derived from the ectoderm.
This lack of signalling from the ectodermal layer is responsible for the absence of Shh expression.
In limbless embryos however, the expression of Wnt-7a is extended to the dorsal and ventral ectoderm, and the expression of C-Lmx1 is extended throughout the limb bud mesoderm, both dorsal and ventral.
www.ucalgary.ca /UofC/eduweb/virtualembryo/sonic.html   (1539 words)

 Mitogen-activated protein kinase and neural specification in Xenopus -- Uzgare et al. 95 (25): 14833 -- Proceedings of ...
ectoderm and ectoderm overexpressing the anterior neural inducer
The induction of anterior neural-gene expression in ectoderm overexpressing noggin was confirmed by RT-PCR.
To investigate the role of MAPK in the response to neural induction, we overexpressed MKP-1 (37, 38) in ectoderm, recombined
www.pnas.org /cgi/content/full/95/25/14833   (3970 words)

 Developmental Biology Online: Vertical and Horizontal Signals from the Organizer
If planar signals traveling from the dorsal blastopore lip through the ectoderm are responsible for neural induction, then the original source of such signals should be the epithelium of the dorsal marginal zone rather than the deep mesenchyme cells of that organizer zone.
This group prepared their exogastrulae in a manner that mechanically excised the ectoderm from the mesoderm and endoderm at the beginning of gastrulation, leaving only a small connection between the dorsal mesoderm and the ectoderm.
The planar signals appear to be involved in inducing the convergent extension of the hindbrain and spinal cord ectoderm adjacent to it (while the folding of the neural plate into a neural tube appears to be induced by the notochord).
www.devbio.com /article.php?ch=10&id=130   (1006 words)

 Eye Problems and Ectodermal Dysplasia (edeye.htm)
An ectodermal dysplasia (ED) is disorder that results from abnormal formation of the ectodermal layer in the developing embryo.
The ectodermal dysplasias are a diverse group of conditions and over a 100 different types have been described.
The ectoderm closes the gap forming the outer part of the cornea, conjunctiva, lids, lacrimal gland and nasolacrimal duct.
www.ectodermaldysplasia.org /edeye.htm   (1704 words)

 Dorlands Medical Dictionary
From it are developed the epidermis and the epidermal tissues, such as the nails, hair, enamel of teeth, and glands of the skin, the nervous system, the external sense organs such as the ear and eye, and the mucous membrane of the mouth and anus.
amniotic ectoderm,   the inner layer of the amnion (and covering of the umbilical cord) that is continuous with body ectoderm.
to-morf)  an individual having a type of body build in which tissues derived from the ectoderm predominate: there is a preponderance of linearity and fragility, with large surface area, thin muscles and subcutaneous tissue, and slightly developed digestive viscera, as contrasted with endomorph and mesomorph.
www.mercksource.com /pp/us/cns/cns_hl_dorlands.jspzQzpgzEzzSzppdocszSzuszSzcommonzSzdorlandszSzdorlandzSzdmd_e_02zPzhtm   (3454 words)

 LvNotch signaling plays a dual role in regulating the position of the ectoderm-endoderm boundary in the sea urchin ...
the mesoderm and ectoderm in the animal region of the embryo.
injected embryos (D) was probably the result of a respective decrease and increase in the amount of ectoderm present after the shift in the ectoderm-endoderm boundary, as the amount of ectoderm in the embryo is thought to regulate the size of sea urchin larvae (Ettensohn and Malinda, 1993).
Activation of LvNotch signaling throughout the embryo expands the SMC territory at the expense of neighboring presumptive endoderm cells (Sherwood and McClay, 1999), and shifts the endoderm territory animally at the expense of presumptive ectoderm (this study).
dev.biologists.org /cgi/content/full/128/12/2221   (7348 words)

 Identification of a Biological Activity That Supports Maintenance and Proliferation of Pluripotent Cells from the ...
comprising primitive ectoderm in the absence of contaminating
embryos were dissected from the uterus, the extraembryonic endoderm associated with the primitive ectoderm was removed mechanically and the embryo was dissected (indicated by the line) to give a portion containing the pluripotent primitive ectoderm cell layer.
of the primitive ectoderm and in subsequent differentiation
www.biolreprod.org /cgi/content/full/69/6/1863   (6526 words)

 ectoderm --¬† Encyclop√¶dia Britannica
In vertebrates, ectoderm subsequently gives rise to hair, skin, nails or hooves, and the lens of the eye; the epithelia (surface, or lining, tissues) of sense organs, the nasal cavity, the sinuses, the mouth (including tooth enamel), and the anal canal; and nervous…
In vertebrates, ectoderm subsequently gives rise to hair, skin, nails or hooves, and the lens of the eye; the epithelia (surface, or lining, tissues) of sense organs, the nasal cavity, the sinuses, the mouth (including tooth enamel), and the anal canal;...
The outermost layer is called the ectoderm; the innermost, the endoderm.
www.britannica.com /eb/article-9031948?tocId=9031948   (725 words)

 Distinct WNT Pathways Regulating AER Formation and Dorsoventral Polarity in the Chick Limb Bud -- Kengaku et al. 280 ...   (Site not responding. Last check: 2007-11-07)
in the proximal ventral ectoderm of the limb (8).
of Wnt3a and Wnt7a overlap in the dorsal ectoderm.
was ectopically induced in the infected limb ectoderm (Fig.
www.sciencemag.org /cgi/content/full/280/5367/1274   (4082 words)

 Hyalin (S. purpuratus)
Concurrent with this morphogenesis, the ectoderm and endoderm change in their relative affinities for hyalin; ectoderm cells retain an affinity while endoderm cells lose their affinity (Burdsal et al., 1991).
As larvae age, a progressive loss of signal is apparent within the aboral ectoderm, beginning in the apex of the embryo and moving progressively toward the oral surface.
Significant mRNA is retained at the boundary between the ciliary band and the oral ectoderm except at the very tips of the arms, where no label is detectable, and at the apex of the oral hood.
www.bio.davidson.edu /courses/genomics/mirror/Urchin/u1hyal.htm   (1080 words)

 eMedicine - Trunk, Embryology : Article by Hongshik Han, MD   (Site not responding. Last check: 2007-11-07)
The 5 pairs of branchial arches that form on either side of the pharyngeal foregut (corresponding to the primitive vertebrae gill bars) on day 22 are the embryologic basis of all the differentiated structures of the head and neck.
Once mesenchymal migration begins, the epiblast layer is termed the embryonic ectoderm and the hypoblast the embryonic endoderm.
Failure of mesenchymal cells to migrate from the somatic mesoderm between the surface ectoderm and the urogenital sinus during the fourth week of development results in failure of striated muscle development.
www.emedicine.com /plastic/topic217.htm   (1529 words)

 BMP controls proximodistal outgrowth, via induction of the apical ectodermal ridge, and dorsoventral patterning in the ...
Brackets outline the domains of expression in the ectoderm (except in F, where the bracket indicates mesenchymal domain), arrowhead in J indicates position of the AER.
ectopic AERs in the ventral ectoderm that are presumed to arise
Bmp and Msx genes are co-expressed in the ventral limb ectoderm,
dev.biologists.org /cgi/content/full/128/22/4463   (9051 words)

 Spemann's induction experiments
Spemann claimed that contact of the optic vesicle with the overlying ectoderm was needed to turn that ectoerm into a lens, but he did not know whether or not it was a sufficient cause.
Moreover, he did not know yet whether the optic cup instructed the ectoderm to form a lens or merely acted as a trigger to permit a pre-existing potency to become expressed.
During the ensuing gastrulation movements, the blastocoel narrows, and the transplant adheres to the inner layer of the ventrolateral ectoderm.
zygote.swarthmore.edu /regul2.html   (1482 words)

 Transient pluripotent cell populations during primitive ectoderm formation: correlation of in vivo and in vitro ...
Transient pluripotent cell populations during primitive ectoderm formation: correlation of in vivo and in vitro pluripotent cell development.
with the expression of this gene in ICM and primitive ectoderm
the primitive ectoderm of the egg cylinder at 5.5 d.p.c.
jcs.biologists.org /cgi/content/full/115/2/329   (6456 words)

 Developmental Biology Online: Pathway For The Induction of the AER
Recent experiments (Laufer et al., 1997; Rodriguez-Esteban et al., 1997; Tanaka et al., 1997) demonstrate that the apposition of dorsal and ventral ectoderm from the chick limb bud is necessary to cause the formation of an AER.
When dorsal limb bud ectoderm was grafted into the ventral ectoderm of another limb bud, a new AER was formed in addition to the original one.
A normal AER can form when normal ectoderm is grafted to the limb field in place of the mutant ectoderm (Carrington and Fallon, 1988).
www.devbio.com /article.php?ch=16&id=160   (1250 words)

 The neural crest is a transient structure that extends along the rostro-
Beneath the ectoderm lies the mesodermal layer and still further inside the embryo the endoderm is found.
as a hollow cylinder of ectoderm, lying beneath the remaining surface ectoderm.
The cells are specified to become part of the neural crest by the inductive action of the dorso-lateral mesoderm which promotes increased levels of BMP which in turn directs the cells to join the neural crest.
cal.man.ac.uk /student_projects/1999/moran/print1.htm   (1213 words)

 Contribution of ectoderm-endoderm boundary to initiation of teeth and adenohypophysis   (Site not responding. Last check: 2007-11-07)
Objectives: Amphibian teeth and adenohypophysis are initiated in the most rostral ectoderm, i.e., oral ectoderm and anterior neural ridge, adjacent to foregut endoderm in the buccopharyngeal membrane at the neurla.
The oral ectoderm attaches to the foregut endoderm, invaginates to the foregut and forms a stomodeal collar, in which larval teeth originate from the thickening epithelium.
Moreover, the trace of the DiI-positive endoderm in LTC showed that the epithelial boundary exists in the region adjacent to the dental epithelium and the adenohypophysis, i.e., the medial parts of pitx2-expressing incisor rudiments, the posterior parts of the pitx2-expressing molar rudiments and the surrounding areas of ACTH-positive adenohypophysis.
iadr.confex.com /iadr/2004Hawaii/techprogram/abstract_46651.htm   (354 words)

 Interactive Fly, Drosophila
The mesoderm cells that come into contact with the dorsal ectoderm receive an inductive signal, Dpp, which triggers the expression of genes such as tinman (tin) and even-skipped (eve) that are required for the differentiation of cardiac and pericardial tissues, respectively.
Both ths and pyr are expressed in the neurogenic ectoderm during the spreading of the internal mesoderm in gastrulating embryos.
Ths and Pyr are required both for the spreading of the mesoderm along the internal surface of the neurogenic ectoderm during gastrulation, as well as the subsequent induction of the dorsal mesoderm to form pericardial tissues (Stathopoulos, 2004).
www.sdbonline.org /fly/newgene/fgfr1-1.htm   (3472 words)

 Organizer molecules
Spemann had favored the assimilatory induction through the ectoderm, but evidence was mounting that the underlying mesoderm was critical.
In that compilation, Johannes Holtfreter demonstrated that when ectoderm is wrapped around the dorsal mesoderm would form brain structures.
In these instances, the ectoderm did not acquire a neural character, again suggesting that the inducing signal appeared to be transmitted vertically from the mesoderm to the ectoderm.
zygote.swarthmore.edu /regul3.html   (780 words)

 [No title]
Weeks 3-8 Deoxygenated blood from the SVC is expelled into the pulmonary artery and ____ ____ to the lower body of the fetus.
Ectoderm Which embryonic tissue are branchial pouches derived from?
Where the hindgut meets ectoderm in the rectum What is the relationship of the two pulmonary arteries in the lung hilus?
umed.med.utah.edu /usmle/PDA/Anatomy.txt   (10754 words)

 Evidence for non-axial A/P patterning in the nonneural ectoderm of Xenopus and zebrafish pregastrula embryos   (Site not responding. Last check: 2007-11-07)
Thus we find that the earliest expression of GATA-2 and 3 is located in nonneural ectoderm and is strongly patterned in a graded manner along the A/P axis, being high anteriorly and absent from the most posterior regions.
These regions correspond to head, trunk and tail ectoderm and may represent the beginnings of functional segmentation of nonneural ectoderm, as suggested in the concept of the 'ectomere'.
We investigate which posteriorizing signals might contribute to such distinct non axial ectodermal patterning in the A/P axis and provide evidence that both FGF and a Wnt family member contribute towards the final A/P pattern of GATA expression in nonneural ectoderm.
www.ijdb.ehu.es /abstract.sept98/42-64.htm   (295 words)

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