SEARCH · PubMed Health

Results for “Ectoderm”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1979

[Association of ectodermal dysplasia, cleft of the lip palate and "scrubbing-brush hair". Its situation in "D. E. F. syndromes" (ectodermal dysplasia, cleft of the lip and/or palate (author's transl)].

The "D. E. F.-syndromes" consist of ectodermal dysplasia, cleft of the lip and/or palate (fente labiale et/ou palatine). This group includes the A. E. C.- and the E. E. C.-syndromes. We are reporting two cases of D. E. F.-syndrome, in which there was a very particular hair dysplasia, which we named "scrubbing-brush hair". The first case was a boy. The disease was probably transmitted on the dominant autosomal mode. The ectodermal dysplasia was of hypohidrotic type. The second case was also observed in a boy. There was no similar genetic abnormality in the family. The ectodermal dysplasia was of hidrotic types. The embryological findings account for the association between the ectodermal dysplasia and the medial dysraphia of the face.

Abnormalities, Multiple↗

PubMed1978

Lack of correlation between mesenchymal cell death and morphogenesis after different extents of apical ectodermal ridge/rim ectoderm removal in the chick embryo wing bud.

The removal of the apical ectodermal ridge (A.E.R.) subsequently causes distal deletion defects in the limb. There have been contradictory reports as to the appearance of cell death in the mesenchyme after A.E.R. removal, as well as to its morphogenetic significance. In our study the A.E.R./ rim ectoderm removal was varied to test whether different degrees of cell death would correlate with different degrees of distal deletions. From the right wing bud of stage 19 and 20 (HH) embryos the rim ectoderm was removed in four ways: all of the rim, the anterior third, the middle third (most of the A.E.R.), or its posterior third. The removal of all or of the anterior third caused a definite band of subwound mesenchymal cell death to appear. There was little or no cell death after removal of the middle or posterior thirds. Removal of the anterior third caused no distal deletion defects, and only a few were noted after removal of the posterior third. The proximo-distal level of the distal deletions, however, was the same after removal of all of the rim or only its middle third. As there was no difference in the degree of distal deletions after the removal of all or of the middle third of the rim but a definite difference in the mesenchymal cell death patterns we conclude that cell death is not part of the mechanisms of the distal deletion defect. Our findings also suggest that cell death does not play a role in the A.E.R.-mesenchyme reciprocal interaction that controls limb proximo-distal morphogenesis.

Animals↗

PubMed2025

Foxi2 and Sox3 are master regulators controlling ectoderm germ layer specification.

In vertebrates, germ layer specification represents a critical transition where pluripotent cells acquire lineage-specific identities. We identify the maternal transcription factors Foxi2 and Sox3 to be pivotal master regulators of ectodermal germ layer specification in Xenopus. Ectopic co-expression of Foxi2 and Sox3 in prospective endodermal tissue induces the expression of ectodermal markers while suppressing mesendodermal markers. Transcriptomics analyses reveal that Foxi2 and Sox3 jointly and independently regulate hundreds of ectodermal target genes. During early cleavage stages, Foxi2 and Sox3 pre-bind to key cis-regulatory modules (CRMs), marking sites that later recruit Ep300 and facilitate H3K27ac deposition, thereby shaping the epigenetic landscape of the ectodermal genome. These CRMs are highly enriched within ectoderm-specific super-enhancers (SEs). Our findings highlight the pivotal role of ectodermal SE-associated CRMs in precise and robust ectodermal gene activation, establishing Foxi2 and Sox3 as central architects of ectodermal lineage specification.

Ep300↗

PubMed1992

Ectopic induction of dorsal mesoderm by overexpression of Xwnt-8 elevates the neural competence of Xenopus ectoderm.

The ectoderm of early Xenopus gastrula is competent to become induced to neural tissue, but dorsal ectoderm is more neural competent than ventral ectoderm. It is a tenable, but as yet untested possibility that the higher neural competence of dorsal gastrula ectoderm is dependent on the presence of the dorsal mesoderm. To test this hypothesis we overexpressed Xwnt-8 in order to ectopically induce dorsal mesoderm in the ventral side of the embryo. We found that this elevated the level of neural competence of ventral ectoderm to that of dorsal ectoderm. The effect of Xwnt-8 on neural competence of ventral ectoderm was strictly correlated with its ability to enhance the amount of dorsal structures. The data indicate that the presence of dorsal mesoderm is a prerequisite for establishing the differences in neural competence between gastrula dorsal and ventral ectoderm.

Animals↗

PubMed2025

Foxi2 and Sox3 are master transcription regulators that control ectoderm germ layer specification in Xenopus.

Germ layer specification represents a critical transition where pluripotent cells acquire lineage-specific identities. We identify the maternal transcription factors Foxi2 and Sox3 to be pivotal master regulators of ectodermal germ layer specification in Xenopus. Ectopic co-expression of Foxi2 and Sox3 in prospective endodermal tissue induces the expression of ectodermal markers while suppressing mesendodermal markers. Transcriptomic analyses reveal that Foxi2 and Sox3 jointly and independently regulate hundreds of ectodermal target genes. During early cleavage stages, Foxi2 and Sox3 pre-bind to key cis-regulatory modules (CRMs), marking sites that later recruit Ep300 and facilitate H3K27ac deposition, thereby shaping the epigenetic landscape of the ectodermal genome. These CRMs are highly enriched within ectoderm-specific super-enhancers (SEs). Our findings highlight the pivotal role of ectodermal SE-associated CRMs in precise and robust ectodermal gene activation, establishing Foxi2 and Sox3 as central architects of ectodermal lineage specification.

Animals↗

PubMed1979

In vitro studies on the morphogenesis and differentiation of the mesoderm subjacent to the apical ectodermal ridge of the embryonic chick limb-bud.

It has been suggested that one of the major functions of the apical ectodermal ridge (AER) of the embryonic chick limb-bud is to maintain mesenchymal cells directly subjacent to it (i.e. cells extending 0.4-- 0.5 mm from the AER) in a labile, undifferentiated condition. We have attempted to directly test this hypothesis by subjecting the undiffertiated subridge mesoderm of stage-25 embryonic chick wing-buds to organ culture in the presence and absence of the AER and the ectoderm that normally surrounds the mesoderm dorsally and ventrally. During the period of culture, control explants comprised of the subridge mesoderm capped by the AER and surrounded by the dorsal/ventral ectoderm undergo progressive morphogenesis characterized by polarized proximal to distal outgrowth and changes in the contour of the developing explant, and ultimately form a structure grossly resembling a normal distal wing-bud tip. In contrast, explants from which the AER and dorsal/ventral ectoderm have been removed (minus ectoderm explants) or from which just the AER has been removed (minus AER explants) form compact, rounded masses exhibiting no signs of morphogenesis. During the polarized proximal to distal outgrowth control explants undergo during the first 3 days of culture, as cells of the explant become located greater than 0.4--0.5 mm from the AER, they concomitantly undergo a sequence of changes indicative of their differentiation into cartilage. However, those cells which remain 0.4--0.5 mm from the AER during this period retain the characteristics of non-specialized mesenchymal cells. In marked contrast to control explants, virtually all of the cells of minus ectoderm explants initiate chondrogenic differentiation during the first day of culture. Cells comprising the central core of minus AER explants also initiate chondrogenic differentiation during the first day of culture, but in contrast to minus ecotderm explants, non-chondrogenic tissue types form along the periphery of the explants subjacent to the dorsal/ventral ectoderm. These results indicate that the AER maintains cells directly subjacent to it in a labile, undifferentiated condition, and that when mesenchymal cells are freed from the AER's influence either artificially or as a result of normal polarized outgrowth, they are freed to commence cytodifferentiation. The results further suggest that the dorsal/ventral ectoderm may have an influence on the differentiation of the mesenchymal cells directly subjacent to it, once the cells have been removed from the influence of the AER.

Animals↗

PubMed1979

The synthesis of hyaluronic acid by ectoderm during early organogenesis in the chick embryo.

This study demonstrates that the dorsal ectoderm of the stage 14 chick embryo synthesizes hyaluronic acid. About 49 to 52% of the H3 glucosamine-labeled glycosaminoglycan that is synthesized by explanted ectoderm can be identified as hyaluronic acid on the basis of its susceptibility to Streptomyces hyaluronidase or isolation of chondroitinase ABC digestion products. In addition, autoradiographic evidence shows that the ectoderm, unlike adjacent tissues like epithelial somites or neural tube, incorporates glucosamine into hyaluronidase-sensitive material which becomes largely extracellular and localized in the subectodermal cell-free space. Ultrastructural evidence shows that there is a fine fibrillar matrix between the ectodermal cells and in the subectodermal spaces when tannic acid is included in the primary fixative. This material resembles authentic hyaluronate, similarly fixed, and is absent when tannic acid is omitted from the fixative or when embryos have been previously treated in ovo with Streptomyces hyaluronidase. The concomitant reduction in the intercellular and subectodermal cell-free spaces after in ovo treatment with Streptomyces hyaluronidase supports the hypothesis that the dorsal ectoderm plays a morphogenetic role by contributing hyaluronate to the forming extracellular spaces. It is proposed that ectodermally derived hyaluronate might influence the morphogenesis of subjacent tissues such as the dermatome and neural crest.

Animals↗

PubMed1975

The function of the ectodermal apical ridge and distinctive characteristics of adjacent distal mesoderm in the avian wing-bud.

Blocks of mesoderm about 0-1 mm in diameter were isolated from various regions of chick wing-buds of stages 17 through 22 and cultured individually, or sometimes in pairs, in microtest plate wells. Cell deaths had occurred after 10 h of culture in those explants that had come from the region associated with the thickest part of the ectodermal ridge, and after 11-12 h in all other mesoderm. When the adjacent ectodermal ridge was left attached to the mesodermal block there were almost no cell deaths for up to 24 h of culture. When the dorsal ectoderm immediately proximal to the apical ridge was left attached, but no ridge was present, cell deaths occurred just as they did in mesoderm with no ectoderm. When a number (usually six) of complete ridges were suspended in a wire basket at the top of a well, cell deaths did not occur in a test mesodermal block at the bottom of the well (six of eight cases). These experiments support previous evivence for a special function of the ectodermal apical ridge in limb morphogenesis, and indicate that there is a chemical messenger. The cells that migrated from distal mesodermal explants (the band up to 0-15 mm from the apical ridge) differed sharply in morphology and behavior from those coming from explants from any more proximal region. Within the proximal mesoderm there was a less striking variation alons the antero-posterior axis. These observations reveal that there is present even at early stages a detailed pattern within the mesoderm of the limb-bud. The particularly striking and distinctive characteristics of that mesoderm closest to the apical ectodermal ridge provide new possibilities for the understanding of the function of the ridge in limb morphogenesis.

Animals↗

PubMed1977

Effects of cytosine arabinoside, 6-aminonicotinamide, and 6-mercaptopurine riboside on ectoderm and mesoderm of mouse limb buds.

The effects of cytosine arabinoside, 6-aminonicotinamide, and 6-mercaptopurine riboside on the incorporation of [14C] glucose moieties and [32P] phosphate into acid-soluble material and lipids, RNA, DNA, and protein were measured in the dissected mesoderm and ectoderm of mouse limb buds at the 42-45 (day 11) somite stage. Due to the different proliferative capacities of the two tissues the incorporation of the precursors into mesodermal cells was considerably higher the than into ectodermal ones. Cytosine arabinoside inhibited the incorporation of the precursor moieties only into DNA, but very early after its application. This effect was more obvious in mesoderm than ectoderm. 6-Aminonicotinamide interfered only with glucose metabolism, whereas the incorporation of phosphate was not affected. 14C radioactivity in the various cell components was similarly reduced in mesoderm and ectoderm. 6-mercaptopurine riboside caused an increased incorporation of precursor material in all fractions studied in the mesoderm as well as in the ectoderm during the first 12 hours. This was succeeded by a dramatic decrease of incorporated 14C and 32P radioactivity. Differences of response in the tissues could not be detected with this drug. It is suggested that the malformations of the extrmities caused by these antimetabolites may be predominantly attributed to changes in the cell function rather than to gross effects on cell metabolism.

6-Aminonicotinamide↗

PubMed1992

Primary culture of single ectodermal precursors of Drosophila reveals a dorsoventral prepattern of intrinsic neurogenic and epidermogenic capabilities at the early gastrula stage.

We have analyzed the development in vitro of individual precursor cells from the presumptive truncal segmental ectoderm of the Drosophila embryo to study the intrinsic component in the determination of cell fate. For each cultured cell, the original position within as well as the developmental stage of the donor embryo were known. Cells removed from the ventral neurogenic region develop neural clones. Cells from the dorsal ectoderm and from the dorsalmost part of the ventral neurogenic ectoderm develop epidermal clones. These two classes of clones differ with respect to their division pattern, adhesiveness, cell morphologies and the expression of cell-specific markers. Mixed neural/epidermal clones were obtained from a fraction of precursors at almost all dorsoventral sites. We conclude that, at the onset of gastrulation, precursor cells of the truncal segmental ectoderm already have the capability to develop as either neuroblasts or epidermoblasts in the absence of further cell interactions. At the same time, positional cues distributed along the dorsoventral axis equip precursors with intrinsic preferences towards the neural or epidermal fate, thus defining a prepattern of high neurogenic preferences ventrally, and high epidermogenic preferences dorsally. It is likely that this prepattern is involved in defining the extent of the ventral neurogenic and dorsal epidermogenic regions of the ectoderm. The roles of intrinsic capabilities versus extrinsic influences in the regulation of the characteristic pattern of segregation of the two lineages are discussed.

Animals↗

PubMed1977

[Morphogenesis of the chick embryo limb. Competence of the embryonic and extra-embryonic ectoderm].

Ecto-mesodermal interactions were investigated during the initiation of limb development in avian embryos. Experiments were performed on 2-day chick embryos. They consisted in implanting prospective leg mesoderm at different medio-lateral levels of the trunk and also into the extra-embryonic area. The implanted mesoderm was thus brought into contact with embryonic or extra-embryonic cicatricial or healing ectoderm, the ability of which to participate in the formation of an ectopic leg was tested. Whatever the level of embryonic ectoderm tested in hosts ranging from stage 14 to 27 pairs of somites (axial, paraxial, flank, ventrum), the experiments resulted in the formation of supernumerary limbs. Their frequency was level-dependent and decreased for each level, with increasing age of the host. The weakest competence was observed in the ectoderm of the prospective ventrum, the strongest in that of the prospective flank, axial and paraxial ectoderm showing an intermediary competence. Extra-embryonic ectoderm of blastoderms of the same age was unable to respond to the inducing action of the implanted prospective leg mesoderm. It was found to be incompetent, even at younger stages (5 to 13 pairs of somites).

Animals↗

PubMed1992

The pattern of expression of the chicken homolog of HOX1I in the developing limb suggests a possible role in the ectodermal inhibition of chondrogenesis.

Homeobox-containing genes have been implicated in a variety of patterning events during vertebrate limb development. In an attempt to isolate cDNAs corresponding to 5' members of the chicken HOX 4 cluster of homeobox-containing genes, a cDNA library constructed from mRNAs expressed during early stages of chick limb development was screened with probes generated by the polymerase chain reaction (PCR) using oligonucleotide primers corresponding to sequences in the homeoboxes of the human HOX4C and HOX4F genes, the human homologs of Hox-4.4 and Hox-4.6. This screening resulted in the isolation of full length cDNAs for the chicken homolog of HOX4F (cognate of mouse Hox-4.6), which we have termed GHox-4.6, and the chicken homolog of human HOX1I, which we have named GHox-1i, a paralog of Hox-4.6 in the HOX 1 cluster. The homeodomains encoded by GHox-4.6 and GHox-1i differ by only three amino acids, and the two proteins show extensive similarity along their entire lengths. Despite their sequence similarity, in situ hybridization analysis has revealed that GHox-4.6 and GHox-1i exhibit strikingly different spatial patterns of expression during embryonic chick limb development. At early stages of limb development (stages 20-22), GHox-4.6 transcripts are present in high amounts throughout the posterior half of the limb mesoderm and are absent from the anterior half of the mesoderm, an expression pattern consistent with the possible involvement of GHox-4.6 in the specification of posterior positional identity. In contrast, GHox-1i exhibits no distinct anterior-posterior polarity of expression at stage 22, but rather is expressed in high amounts throughout the mesenchyme of the limb bud. At later stages of development (stage 25), GHox-1i continues to be expressed in high amounts throughout the undifferentiated mesenchyme subjacent to the apical ectodermal ridge, and, in addition, is expressed in the mesodermal cells in the proximal peripheral regions of the limb bud subjacent to the ectoderm which are differentiating into nonchondrogenic lineages. Conversely, little or no expression of GHox-1i is detectable in the proximal central core of the limb bud where chondrogenic differentiation is occurring. Thus, GHox-1i is expressed by the undifferentiated subridge mesenchymal cells and proximal peripheral mesenchymal cells of the limb bud that are being inhibited from undergoing chondrogenesis by the apical ectodermal ridge and nonridge ectoderm.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1992

Ectodermal dysplasias associated with clefting: significance of scalp dermatitis.

Several clinical syndromes are characterized by ectodermal dysplasia (ED) in association with clefting of the lip and/or palate. The three most commonly recognized entities are (1) the EEC syndrome (ectodermal dysplasia, ectrodactyly, cleft lip/palate); (2) the Rapp-Hodgkin syndrome with ectodermal dysplasia, cleft lip/palate, and mid facial hypoplasia; and (3) the Hay-Wells or AEC syndrome (ankyloblepharon, ectodermal defects, cleft lip/palate). The clinical characteristics of these entities as well as several less common syndromes are reviewed and summarized. The presence of scalp dermatitis in patients with the AEC syndrome and less often the Rapp-Hodgkin syndrome is emphasized.

Cleft Lip↗

PubMed1979

Anhidrotic ectodermal dysplasia with lacrimal anomalies.

Ectodermal dysplasia and its related disorders may present with ocular symptoms due to involvement of the ectodermal components of the eye. This paper reports a case of congenital anhidrotic ectodermal dysplasia presenting to the ophthalmologist with epiphora due to lacrimal atresia. The embryonic origin of the lacrimal system suggests that lacrimal anomalies in association with ectodermal disorders are commoner than reports indicate. Their management consists in accurate evaluation of the anomaly followed by surgery.

Child↗

PubMed1976

Development of teratomas from the ectoderm of mouse egg cylinders.

We studied the developmental capacities of the primary ectoderm and endoderm of 6-day embryos of hybrids between strains 129/Sv-SIJ C P and A/He mice by grafting these germ layers into the testes of adult mice for 30 days. Grafts of embryonic ectoderm gave rise to teratocarcinomas composed of undifferentiated embryonal cells and derivatives of all three germ layers including respiratory and alimentary epithelium. Grafts of extraembryonic ectoderm gave rise to invasive trophoblastic giant cells. Grafts of endoderm did not develop.

Animals↗

PubMed1975

[Hidrotic ectodermal dysplasia].

This paper reports a family with typical features of hidrotic ectodermal dysplasia (h.e.d.). Although some members of the family showed phenotypical similarities to anhidrotic ectodermal dysplasia, there is no doubt about the classification of this disorder into hidrotic ectodermal dysplasia because of its manifest symptomatology (hypo- and dystrichosis deformity of nails, autosomal-dominant heredity, normal sweating). This suggests that the phenotypical similarities are obvious and important findings of h.e.d.

Adolescent↗

PubMed1978

[Lenticular and adenohypophyseal differentiation in the oral region ectoderm of chick embryos in tissue culture].

The ectoderm of oral regions from the chick embryos at the stage of 10 to 19 somites was cultivated in vitro and on chorioallantois in the complex with underlying tissues. In all the explants which, besides ectoderm, contained head gut and mesenchyme, lentoids and lenses formed within 6 days of in vitro cultivation. All specific antigens of chicken lens (alpha, beta- and delta-crystallins) were found in them by means of immunofluorescence. In the explants which contained diencephalon, besides single lentoids or lenses, adenohypophyses were found. The possibility of direct lens-inducing effect of the head gut endoderm on the ectoderm of oral region and the participation of diencephalon in this process are discussed.

Animals↗

PubMed1975

The community of human malformation syndromes that shares ectodermal dysplasia and deformities of the hands and feet.

Syndromes of human congenital malformation may be classified be recognizing communities of syndromes that share multiple phenotypic similarities involving their principal diagnostic features. A community of syndromes that shares various expressions of ectodermal dysplasia and various deformities of the hands and feet is proposed; these syndromes are divisible into two classes according to the presence or absence of anomalies in the nasal or labial regions of the face. The dysmorphogenetic validity of the division is supported by the fact that the syndromes without nasal or labial anomalies have a high frequency of sensorineural deafness as one expression of ectodermal dysplasia whereas those without such anomalies do not. The usefulness of such a syndromal community as a base for evolving a taxonomic scheme of dysmorphogenetic relatedness amongst different syndromes is illustrated.

Abnormalities, Multiple↗