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At least 577 records · Page 32Linked to original sources
PubMed1991

Sweat testing to identify female carriers of X linked hypohidrotic ectodermal dysplasia.

X linked hypohidrotic ectodermal dysplasia (XHED) affects many epithelial functions, including sweat gland formation. Female carriers who manifest XHED may have defective dentition or a patchy distribution of sweating or both, as determined by starch and iodine sweat testing. Such sweat testing can be useful in assigning carrier status to at risk females in XHED families, and in obtaining an accurate diagnosis for isolated females who present with features of ectodermal dysplasia. The advantages of diagnosing female carriers of XHED include the optimisation of neonatal and paediatric care for affected male infants, who may be at substantial risk of death in infancy.

Adult↗
PubMed1993

Hypohidrotic ectodermal dysplasia, central nervous system malformation, and distinct facial features: confirmation of a distinct entity?

Internal hydrocephalus with partial hypoplasia of the cerebellum was observed in a severely mentally retarded boy who showed signs of ectodermal dysplasia. Diagnostic considerations are discussed. Reports of the triad mental retardation-CNS malformation-ectodermal dysplasia are rare. In 1989 we reported a case with these signs that shows a striking facial similarity to the case presented here.

Brain↗
PubMed1998

Autosomal recessive anhidrotic ectodermal dysplasia in a large Moroccan family.

We studied a large Moroccan family in which anhidrotic ectodermal dysplasia is transmitted as an autosomal recessive trait. Fourteen family members, both males and females, were affected and they all had a common ancestor. Linkage analysis by homozygosity mapping in this family will permit the gene localisation of this rare form of anhidrotic ectodermal dysplasia.

Child↗
PubMed2001

Ectodermal dysplasias: a new clinical-genetic classification.

The ectodermal dysplasias (EDs) are a large and complex nosological group of diseases, first described by Thurnam in 1848. In the last 10 years more than 170 different pathological clinical conditions have been recognised and defined as EDs, all sharing in common anomalies of the hair, teeth, nails, and sweat glands. Many are associated with anomalies in other organs and systems and, in some conditions, with mental retardation.The anomalies affecting the epidermis and epidermal appendages are extremely variable and clinical overlap is present among the majority of EDs. Most EDs are defined by particular clinical signs (for example, eyelid adhesion in AEC syndrome, ectrodactyly in EEC). To date, few causative genes have been identified for these diseases. We recently reviewed genes known to be responsible for EDs in light of their molecular and biological function and proposed a new approach to EDs, integrating both molecular-genetic data and corresponding clinical findings. Based on our previous report, we now propose a clinical-genetic classification of EDs, expand it to other entities in which no causative genes have been identified based on the phenotype, and speculate on possible candidate genes suggested by associated "non-ectodermal" features.

Ectodermal Dysplasia↗
PubMed1984

Differentiation of presumptive lens ectoderm of the chick in vitro studied with immunofluorescence techniques.

The differentiation capacity of presumptive lens ectoderm was studied in the chick by an in vitro technique using the appearance of central nervous system or lens-specific antigens as indicators of differentiation. Handling the explants resulted in 'autodifferentiation' of both antigens, but co-culture with alcohol-killed primitive node or optic cup material could induce much stronger differentiation. Little specificity exists in the reaction and a hypothesis is presented whereby selection between the two differentiation pathways is thought to be due mainly to maturation within the ectoderm and the inducing tissue plays a minor qualitative role.

Animals↗
PubMed1988

Ultrastructural study of contacts between cells of the dorsal ectoderm and chordamesoderm during gastrulation in Xenopus laevis.

In gastrulae of Xenopus laevis, various morphological types of intercellular approximation occur between the dorsal ectoderm and chordamesoderm. Ruthenium red staining reveals that in some areas the glycocalyces of heterotypic cells appear to come into contact. These observations, in conjunction with the results of previous studies, suggest that cell contacts offer a possible pathway for the transmission of inductive stimuli, and that they may be important in the regionalization of the neuralized ectoderm.

Animals↗
PubMed1994

Direct vs. indirect effects of trypan blue on the ectodermal cells of the 11.5-day rat embryo?

The effect of trypan blue on the 11.5-day rat conceptus after intravitelline vessel administration is described. For comparison, conceptuses injected with varying volumes of Hanks' BSS have also been studied. Trypan blue significantly retarded the growth and development of conceptuses after 6 hours incubation in vitro. The SEM revealed rounded ectodermal cells, some of which appeared disrupted. These cells seemed to cause some of the intersomitic grooves to disappear, making a number of the somites indistinct from the outside. Unlike cells of uninjected embryos, the surfaces of the affected ectodermal cells lacked microvilli and their perimeters were lined with microvilli-like structures which appeared matted together. It was concluded that trypan blue affected the embryo directly probably by disturbing its fluid and ionic balance.

Animals↗
PubMed1998

The gene defective in anhidrotic ectodermal dysplasia is expressed in the developing epithelium, neuroectoderm, thymus, and bone.

Anhidrotic ectodermal dysplasia (EDA) is characterized by defects in the development of teeth, hair, and sweat glands. To study the expression of the human gene defective in EDA in human fetal development (Weeks 6-23 of gestational age) and in adult tissues, in situ hybridization and immunohistochemistry were used. First signs of expression were detected at Week 8 in epidermis and in neuroectodermal cells. Starting at Week 12, osteoblasts and thymus were positive for EDA mRNA. Hair follicles expressed EDA mRNA from 18 weeks. The presence of the EDA protein coincided with mRNA expression in the tissues examined. The expression pattern of the EDA gene is consistent with typical involvement of the skin in the syndrome. However, the expression is not limited to the ectodermal tissues and many sites of expression are not obviously reflected in the clinical features of the syndrome.

Adult↗
PubMed1983

Evidence from thiol histochemistry for homology between the Tabby-crinkled syndrome in mice and human ectodermal dysplasia.

Mutant mice carrying the sex-linked gene Tabby (Ta), and others carrying crinkled (cr), an autosomal mimic of Ta, were studied histochemically with respect to the sulfhydryl: disulfide ratios in their skin and hair and the SH levels in their tooth germs. As compared to normal controls, the mutant animals demonstrated significantly elevated SH:S-S ratios (skin and hair) and SH levels (tooth germs) in the ectodermal components of these tissues. This finding corresponds with previously reported biochemical data on a form of human ectodermal dysplasia (ED), and therefore supports the hypothesis that these mutations in mice may be homologous to the genes for human ED.

Animals↗
PubMed1977

Calcification of basal ganglia and cerebellar roof nuclei in mentally defective patient with hidrotic ectodermal dysplasia. Analysis of intracranial concretions by electon microprobe.

This report describes, for the first time, an analysis by electron microprobe of concretions in the brain of an individual with striopallidodentate calcification. We also report the unique association of this intracranial syndrome with hidrotic ectodermal dysplasia. An institutionalized male with impaired intellectual function and hidrotic ectodermal dysplasia was known since the age of 3 years to have bilateral radiopaque densities in the region of the basal ganglia on skull roentgenogram. He died at age 29 in congestive heart failure from rheumatic pancarditis. At autopsy, concretions were identified in globus pallidus, caudate nuclei, thalamus, and dentate nuclei. Mineral deposits within the brain, analyzed by energy dispersive x-ray microanalysis, consisted predominately of calcium and phosphorus. Trace amounts of magnesium, iron, and silicon also were detected.

Adult↗
PubMed2003

A zone of frontonasal ectoderm regulates patterning and growth in the face.

A fundamental set of patterning genes may define the global organization of the craniofacial region. One of our goals has been to identify these basic patterning genes and understand how they regulate outgrowth of the frontonasal process, which gives rise to the mid and upper face. We identified a molecular boundary in the frontonasal process ectoderm, defined by the juxtaposed domains of Fibroblast growth factor 8 and Sonic hedgehog, which presaged the initial site of frontonasal process outgrowth. Fate maps confirmed that this boundary region later demarcated the dorsoventral axis of the upper beak. Ectopic transplantation of the ectodermal boundary region activated a cascade of molecular events that reprogrammed the developmental fate of neural crest-derived mesenchyme, which resulted in duplications of upper and lower beak structures. We discuss these data in the context of boundary/morphogen models of patterning, and in view of the recent controversy regarding neural crest pre-patterning versus neural crest plasticity.

Animals↗
PubMed2004

Combinatorial Fgf and Bmp signalling patterns the gastrula ectoderm into prospective neural and epidermal domains.

Studies in fish and amphibia have shown that graded Bmp signalling activity regulates dorsal-to-ventral (DV) patterning of the gastrula embryo. In the ectoderm, it is thought that high levels of Bmp activity promote epidermal development ventrally, whereas secreted Bmp antagonists emanating from the organiser induce neural tissue dorsally. However, in zebrafish embryos, the domain of cells destined to contribute to the spinal cord extends all the way to the ventral side of the gastrula, a long way from the organiser. We show that in vegetal (trunk and tail) regions of the zebrafish gastrula, neural specification is initiated at all DV positions of the ectoderm in a manner that is unaffected by levels of Bmp activity and independent of organiser-derived signals. Instead, we find that Fgf activity is required to induce vegetal prospective neural markers and can do so without suppressing Bmp activity. We further show that Bmp signalling does occur within the vegetal prospective neural domain and that Bmp activity promotes the adoption of caudal fate by this tissue.

Animals↗
PubMed2004

Six1 promotes a placodal fate within the lateral neurogenic ectoderm by functioning as both a transcriptional activator and repressor.

Cranial placodes, which give rise to sensory organs in the vertebrate head, are important embryonic structures whose development has not been well studied because of their transient nature and paucity of molecular markers. We have used markers of pre-placodal ectoderm (PPE) (six1, eya1) to determine that gradients of both neural inducers and anteroposterior signals are necessary to induce and appropriately position the PPE. Overexpression of six1 expands the PPE at the expense of neural crest and epidermis, whereas knock-down of Six1 results in reduction of the PPE domain and expansion of the neural plate, neural crest and epidermis. Using expression of activator and repressor constructs of six1 or co-expression of wild-type six1 with activating or repressing co-factors (eya1 and groucho, respectively), we demonstrate that Six1 inhibits neural crest and epidermal genes via transcriptional repression and enhances PPE genes via transcriptional activation. Ectopic expression of neural plate, neural crest and epidermal genes in the PPE demonstrates that these factors mutually influence each other to establish the appropriate boundaries between these ectodermal domains.

Animals↗
PubMed2007

Ectodysplasin has a dual role in ectodermal organogenesis: inhibition of Bmp activity and induction of Shh expression.

Ectodermal organogenesis is regulated by inductive and reciprocal signalling cascades that involve multiple signal molecules in several conserved families. Ectodysplasin-A (Eda), a tumour necrosis factor-like signalling molecule, and its receptor Edar are required for the development of a number of ectodermal organs in vertebrates. In mice, lack of Eda leads to failure in primary hair placode formation and missing or abnormally shaped teeth, whereas mice overexpressing Eda are characterized by enlarged hair placodes and supernumerary teeth and mammary glands. Here, we report two signalling outcomes of the Eda pathway: suppression of bone morphogenetic protein (Bmp) activity and upregulation of sonic hedgehog (Shh) signalling. Recombinant Eda counteracted Bmp4 activity in developing teeth and, importantly, inhibition of BMP activity by exogenous noggin partially restored primary hair placode formation in Eda-deficient skin in vitro, indicating that suppression of Bmp activity was compromised in the absence of Eda. The downstream effects of the Eda pathway are likely to be mediated by transcription factor nuclear factor-kappaB (NF-kappaB), but the transcriptional targets of Edar have remained unknown. Using a quantitative approach, we show in cultured embryonic skin that Eda induced the expression of two Bmp inhibitors, Ccn2/Ctgf (CCN family protein 2/connective tissue growth factor) and follistatin. Moreover, our data indicate that Shh is a likely transcriptional target of Edar, but, unlike noggin, recombinant Shh was unable to rescue primary hair placode formation in Eda-deficient skin explants.

Animals↗
PubMed1989

The albino-deletion complex in the mouse defines genes necessary for development of embryonic and extraembryonic ectoderm.

A detailed embryological analysis has been undertaken on embryos carrying the c4FR60Hd-, c5FR60Hg- or c2YPSj-albino deletions of mouse chromosome 7. Embryos homozygous for the c4FR60Hd deletion are abnormal at day 7.5 of gestation. The extraembryonic ectoderm does not develop, and primitive-streak formation and mesoderm production do not occur. In contrast, extensive development of the extraembryonic ectoderm, as well as mesoderm production, are observed in the c5FR60Hg- and c2YPSj-homozygous embryos. The mesoderm does not, however, organize into somites and the neural axis does not form. The embryos are grossly abnormal by day 8.5 of development. There are two other albino deletions (c6H and c11DSD) that are known to affect the embryo around the time of gastrulation (Niswander et al. 1988), and the lethal phenotype observed for the c4FR60Hd-homozygous embryos is similar to that described for c6H-homozygous embryos, whereas the c5FR60Hg- and c2YPSj-homozygous embryos display a phenotype that is similar to c11DSD-homozygous embryos. A detailed complementation analysis using these five deletions revealed that the c5FR60Hg, c2YPSj and c11DSD deletions could partially complement the phenotype produced by the c4FR60Hd and c6H deletions in any combination. Extensive development of the extraembryonic structures and production of mesoderm occurs in the compound heterozygotes. These results suggest that the distal breakpoints of the c5FR60Hg, c2YPSj and c11DSD deletions lie more proximal than the distal breakpoints of the c4FR60Hd and c6H deletions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Retinoic acid application to chick wing buds leads to a dose-dependent reorganization of the apical ectodermal ridge that is mediated by the mesenchyme.

Local application of retinoic acid to wing buds of chick embryos leads to dose- and position-dependent changes in the pattern of cellular differentiation. Early effects of retinoid treatment on the apical ectodermal ridge coordinate pattern changes and morphogenesis. The length of the apical ridge increases when additional digits will form but decreases when digits are lost. These changes in length can be understood in terms of a threshold response to the local retinoid concentration that results in either disappearance or maintenance of the ridge (Lee & Tickle, J. Embryol. exp. Morph. 90, 139-169 (1985)). Here, we have analysed the mechanisms involved in ridge disappearance by locally applying retinoic acid to the apex of stage 20 chick wing buds. With this treatment regime, low doses give duplicated digit patterns and higher doses truncations. The height of the apical ridge is progressively reduced with increasing doses of retinoid and the time course of ridge flattening indicates that the height of the ridge is correlated with bud outgrowth. With high doses of retinoic acid, the typical ridge, a pseudostratified epithelium in which the columnar cells are tightly packed, disappears and the epithelium at the tip of the bud consists of loosely packed cuboidal cells. Shortly after treatment, there is a decrease in the number of gap junctions between ridge cells. This early change in cell contacts suggests that gap junctions may be involved in maintaining epithelial morphology. When treated epithelium is recombined with untreated mesenchyme, an apical ridge is reestablished and distal structures can be generated. In contrast, when treated mesenchyme is recombined with the epithelium from normal buds, only proximal structures are formed. Therefore, retinoids can lead to a reorganization of the apical ectodermal ridge which is mediated and maintained by the mesenchyme.

Animals↗
PubMed1990

Ectoderm nuclei from sea urchin embryos contain a Spec-DNA binding protein similar to the vertebrate transcription factor USF.

The Spec gene family of Stronglyocentrotus purpuratus is expressed exclusively in aboral ectoderm cells during embryogenesis. To investigate the regulation of Spec gene activity, the region around the Spec1 transcriptional initiation site was analyzed for sites of protein-DNA interaction. One high-affinity site bound a factor termed SpF1 within the Spec1 5' untranslated leader region at position +39 to +60. The core sequence recognized by SpF1, CACGTG, is the same as that of the upstream stimulatory factor (USF), a widely occurring vertebrate transcription factor containing a myc-HLH motif. A comparison of USF- and SpF1-binding activities suggested that SpF1 was a sea urchin version of USF. SpF1 activity was detectable only in ectoderm cells of the embryo, implying that it has a role as a cell type-specific transcription factor. SpF1-binding sites were also found upstream of the Spec2a and Spec2c genes in the same conserved sequence block as Spec1. Extracts from Lytechinus pictus embryos showed an SpF1-like activity, suggesting that SpF1 is conserved in sea urchins. Surprisingly, changes in the Spec1, Spec2a, or Spec2c genes that removed or modified the SpF1-binding site had no effect on expression when reporter gene fusions containing these mutations were injected into sea urchin eggs and analyzed for expression during embryogenesis. We propose that, while SpF1 may not be essential for expression of the exogenously introduced reporter genes, it may be required for proper regulation of the endogenous Spec genes.

Animals↗
PubMed1991

Development of the Xenopus laevis hatching gland and its relationship to surface ectoderm patterning.

An antibody that recognizes tyrosine hydroxylase can be used as a marker for hatching gland cells in Xenopus embryos. Using this marker, we have shown that hatching gland cells are induced at the end of gastrulation and that presumptive hatching gland cells are localized to the anterior neural folds in Xenopus. The movements of neurulation bring the hatching gland cells together to form a characteristic Y pattern on the dorsoanterior surface of the head. The Y pattern delineates several zones of surface ectoderm which can be visualized by the presence or absence of ciliated cells. As development proceeds the hatching gland pattern is altered, demonstrating the active changes involved in forming the face. Lithium, UV irradiation and retinoic acid can be used to alter the hatching gland pattern in specific ways which help to understand the underlying mechanisms of ectodermal patterning.

Animals↗