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At least 307 records · Page 17Linked to original sources
PubMed1990

Two unusual congenital anomalies of the tricuspid valve.

We describe two unusual congenital anomalies of the tricuspid valve discovered incidentally at autopsy. One is an abnormal attachment of the tricuspid septal leaflet to one of two posterior papillary muscles with a concomitant fusion of the right ventricular septal and anterior papillary muscles in a patient with ectodermal dysplasia. The other involves a fenestration defect of the septal leaflet of the tricuspid valve in a patient with aortic stenosis, coronary artery atherosclerosis, and cardiac amyloidosis.

Adolescent↗
PubMed1989

Ichthyosis with an unusual constellation of ectodermal dysplasias.

A unique disorder characterized by ichthyosis and defects of the appendages and teeth is reported. Scaly skin and absence of sweating were observed shortly after birth. During childhood there was progressive loss of hair, severe abnormalities of dentition and dystrophic changes of the nails following minor trauma. The patient experienced corneal ulceration, and examination of the eyes revealed a reduced number of meibomian glands and changes in the cornea consistent with previous ulcers. Dryness of the mucous membranes of the mouth was also observed. There is no previous report of an individual with this constellation of changes.

Alopecia↗
PubMed1988

The team approach to the management of ectodermal dysplasias.

1. The medical and dental needs of ED patients require multidisciplinary treatment. Because of the difficulty in identifying centers with genetic and dental services, locating the availability of these services should be undertaken first. 2. A team member for the specialties of genetics, pediatrics, dermatology, opthalmology, otolaryngology, orthodontics, prosthetics, and pediatric/general dentistry must be identified at each center. 3. An individual to act as liaison with other groups must be identified. 4. A team leader must be named; this individual may be the same or different from the specialists, and local teams must be established. 5. A protocol for communication among national and regional centers, identified specialists, and local teams must be established. 6. Each center should attempt to identify specialists in the region interested in participation. 7. Demographics of identified families need to be established. 8. As patient populations are found, the need for new centers can be identified. 9. As groups of the necessary specialists are identified in a need area, the establishment of new centers can begin. 10. A protocol for uniform record keeping and the centralization of the record base should be established. 11. Treatment protocols should be established to allow coordination of treatment and to support the research aspects of the centers. 12. Efforts need to be directed at establishing financial support for treatment not covered by third-party carriers. 13. Lobbying efforts need to be planned to seek changes in existing laws to provide for adjunctive dental care coverage under medical insurance policies. 14. Efforts need to be initiated to seek private and public funding for the centers. Grant preparation needs to be undertaken to seek support for research activities. 15. A protocol for the recording of ectodermal dysplasia information through a central registry, as is done through the Centers for Disease Control (CDC) with other recognized birth defects, is called for.

Ectodermal Dysplasia↗
PubMed1992

The function of the neurogenic genes during epithelial development in the Drosophila embryo.

The complex embryonic phenotype of the six neurogenic mutations Notch, mastermind, big brain, Delta, Enhancer of split and neuralized was analyzed by using different antibodies and PlacZ markers, which allowed us to label most of the known embryonic tissues. Our results demonstrate that all of the neurogenic mutants show abnormalities in many different organs derived from all three germ layers. Defects caused by the neurogenic mutations in ectodermally derived tissues fell into two categories. First, all cell types that delaminate from the ectoderm (neuroblasts, sensory neurons, peripheral glia cells and oenocytes) are increased in number. Secondly, ectodermal tissues that in the wild type form epithelial structures lose their epithelial phenotype and dissociate (optic lobe, stomatogastric nervous system) or show significant differentiative abnormalities (trachea, Malpighian tubules and salivary gland). Abnormalities in tissues derived from the mesoderm were observed in all six neurogenic mutations. Most importantly, somatic myoblasts do not fuse and/or form an aberrant muscle pattern. Cardioblasts (which form the embryonic heart) are increased in number and show differentiative abnormalities; other mesodermal cell types (fat body, pericardial cells) are significantly decreased. The development of the endoderm (midgut rudiments) is disrupted in most of the neurogenic mutations (Notch, Delta, Enhancer of split and neuralized) during at least two stages. Defects occur as early as during gastrulation when the invaginating midgut rudiments prematurely lose their epithelial characteristics. Later, the transition of the midgut rudiments to form the midgut epithelium does not occur. In addition, the number of adult midgut precursor cells that segregate from the midgut rudiments is strongly increased. We propose that, at least in the ectodermally and endodermally derived tissues, neurogenic gene function is primarily involved in interactions among cells that need to acquire or to maintain an epithelial phenotype.

Animals↗
PubMed2001

Signaling and subcellular localization of the TNF receptor Edar.

Tabby and downless mutant mice have identical phenotypes characterized by deficient development of several ectodermally derived organs such as teeth, hair, and sweat glands. Edar, encoded by the mouse downless gene and defective in human dominant and recessive forms of autosomal hypohidrotic ectodermal dysplasia (EDA) syndrome, is a new member of the tumor necrosis factor (TNF) receptor superfamily. The ligand of Edar is ectodysplasin, a TNF-like molecule mutated in the X-linked form of EDA and in the spontaneous mouse mutant Tabby. We have analyzed the response of Edar signaling in transfected cells and show that it activates nuclear factor-kappaB (NF-kappaB) in a dose-dependent manner. When Edar was expressed at low levels, the NF-kappaB response was enhanced by coexpression of ectodysplasin. The activation of NF-kappaB was greatly reduced in cells expressing mutant forms of Edar associated with the downless phenotype. Overexpression of Edar did not activate SAPK/JNK nor p38 kinase. Even though Edar harbors a death domain its overexpression did not induce apoptosis in any of the four cell lines analyzed, nor was there any difference in apoptosis in developing teeth of wild-type and Tabby mice. Additionally, we show that the subcellular localization of dominant negative alleles of downless is dramatically different from that of recessive or wild-type alleles. This together with differences in NF-kappaB responses suggests an explanation for the different mode of inheritance of the different downless alleles.

Alleles↗
PubMed1996

Concanavalin-A-induced open neural tube defects in chick embryos.

Open neural tube defects developed in 12 of 122 alive chick embryos treated with exogenous lectin (concanavalin-A) at stages between 10 or 14 as defined by Hamburger and Hamilton. Embryos treated at stage 10, the time of anterior neuropore closure, developed exencephaly or extensive neural openings from the level of rhombencephalon to the thoracic spinal cord, while embryos treated at stages between 11 and 14, at posterior neuropore closure, developed only small myeloschisis in the thoracolumbar region. The failure of neural tube closure at a critical time is a major cause of neural tube defects.

Animals↗
PubMed2006

EDA signaling and skin appendage development.

The same morphogenetic signals are often involved in the development of different organs. For developing skin appendages, a model for tissue-specific regulation of signaling is provided by the EDA pathway, which accesses the otherwise ubiquitous NFkappaB transcription factors. EDA signaling is mediated by ectodysplasin, EDAR and EDARADD, which form a new TNF ligand-receptor-adaptor family that is restricted to skin appendages in vertebrates from fish to human. The critical function of the pathway was demonstrated in the hereditary genetic disorder Anhidrotic Ectodermal Dysplasia (EDA), which is characterized by defective formation of hair follicles, sweat glands and teeth. The pathway does not appear to initiate the development of the appendages, but is regulated by and regulates the course of further morphogenesis. In mice, transgenic and knockout strains have increasingly revealed features of the mechanism, and suggest possible non-invasive interventions to alleviate EDA deficiency, especially in sweat glands and eyes.

Amino Acid Sequence↗
PubMed1999

Aplasia cutis congenita in an infant of an initial triplet gestation: a case report.

Aplasia cutis congenita (ACC) is the clinical manifestation of an uncommon group of skin disorders. One postulated etiology is disseminated intravascular coagulation from release of thrombogenic maternal arising from placental injury or fetal demise. This leads to disruption of the ectodermal blood supply responsible for the skin defects. We present a neonate with group V ACC, one of an initial triplet gestation, associated with fetal demise at 14 weeks and formation of a fetus papyraceus. The practice of selective fetal reduction as a result of multiple gestation seen with the use of fertility drugs may in theory increase the incidence of group V ACC.

Administration, Topical↗
PubMed1995

"New" ectodermal dysplasia with mental retardation and syndactyly.

We describe a girl with an unusual form of ectodermal dysplasia. She was mildly mentally retarded, had normal height, weight, and head circumference, a large scalp defect, a peculiar face with large palpebral fissures, a broad nasal bridge and constantly open mouth, abnormally-modeled ears, syndactyly of fingers/toes, mild hypohidrosis, and severe onychogryposis. Her hair was short, abundant, and stiff, her eyebrows were sparse, and her skin was dry. Analysis of the literature showed that this type of association of ectodermal dysplasia and other defects has not been previously described.

Abnormalities, Multiple↗
PubMed2003

Ablation of specific expression domains reveals discrete functions of ectoderm- and endoderm-derived FGF8 during cardiovascular and pharyngeal development.

Fibroblast growth factor 8 (Fgf8) is expressed in many domains of the developing embryo. Globally decreased FGF8 signaling during murine embryogenesis results in a hypomorphic phenotype with a constellation of heart, outflow tract, great vessel and pharyngeal gland defects that phenocopies human deletion 22q11 syndromes, such as DiGeorge. We postulate that these Fgf8 hypomorphic phenotypes result from disruption of local FGF8 signaling from pharyngeal arch epithelia to mesenchymal cells populating and migrating through the third and fourth pharyngeal arches. To test our hypothesis, and to determine whether the pharyngeal ectoderm and endoderm Fgf8 expression domains have discrete functional roles, we performed conditional mutagenesis of Fgf8 using novel Crerecombinase drivers to achieve domain-specific ablation of Fgf8 gene function in the pharyngeal arch ectoderm and endoderm. Remarkably, ablating FGF8 protein in the pharyngeal arch ectoderm causes failure of formation of the fourth pharyngeal arch artery that results in aortic arch and subclavian artery anomalies in 95% of mutants; these defects recapitulate the spectrum and frequency of vascular defects reported in Fgf8 hypomorphs. Surprisingly, no cardiac, outflow tract or glandular defects were found in ectodermal-domain mutants, indicating that ectodermally derived FGF8 has essential roles during pharyngeal arch vascular development distinct from those in cardiac, outflow tract and pharyngeal gland morphogenesis. By contrast, ablation of FGF8 in the third and fourth pharyngeal endoderm and ectoderm caused glandular defects and bicuspid aortic valve, which indicates that the FGF8 endodermal domain has discrete roles in pharyngeal and valvar development. These results support our hypotheses that local FGF8 signaling from the pharyngeal epithelia is required for pharyngeal vascular and glandular development, and that the pharyngeal ectodermal and endodermal domains of FGF8 have separate functions.

Animals↗
PubMed2006

The mouse Ovol2 gene is required for cranial neural tube development.

The Ovo gene family encodes a group of evolutionarily conserved transcription factors and includes members that reside downstream of key developmental signaling pathways such as Wg/Wnt and BMP/TGF-beta. In the current study, we explore the function of Ovol2, one of three Ovo paralogues in mice. We report that Ovol2 is expressed during early-mid embryogenesis, particularly in the inner cell mass at E3.5, in epiblast at E6.5, and at later stages in ectodermally derived tissues such as the rostral surface (epidermal) ectoderm. Embryos in which Ovol2 is ablated exhibit lethality by E10.5, prior to which they display severe defects including an open cranial neural tube. The neural defects are associated with improper Shh expression in the underlying rostral axial mesoderm and localized changes of neural marker expression along the dorsoventral axis, as well as with expanded cranial neural tissue and reduced cranial surface ectoderm culminating in a lateral shift of the neuroectoderm/surface ectoderm border. We propose that these defects reflect the involvement of Ovol2 in independent processes such as regionalized gene expression and neural/non-neural ectodermal patterning. Additionally, we present evidence that Ovol2 is required for efficient migration and survival of neural crest cells that arise at the neuroectoderm/surface ectoderm border, but not for their initial formation. Collectively, our studies indicate that Ovol2 is a key regulator of neural development and reveal a previously unexplored role for Ovo genes in mammalian embryogenesis.

Animals↗
PubMed1976

Midline cutaneous and spinal defects. Midline cutaneous abnormalities associated with occult spinal disorders.

Failure of separation of the neuroectoderm from the epithellal ectoderm to proceed in an orderly and complete fashion results in a wide variety of defects involving the skin, spinal cord, and cauda equina, as well as the surrounding structures of mesodermal origin. Congenital dermal sinuses occur most commonly in the lumbosacral region, are usually associated with a spina bifida, and may connect the skin directly to the spinal canal. Epidermoid or dermoid cysts may form at any point along a dermal sinus. Four types of cutaneous or subcutaneous abnormalities commonly seen associated with occult spinal disorders are abnormal hair, angioma, lipoma, and dimple. It is essential that these lesions are investigated at an early age, since surgical excision may prevent future neurologic deficits.

Adolescent↗
PubMed1997

Cranial anomaly of homozygous rSey rat is associated with a defect in the migration pathway of midbrain crest cells.

Craniofacial development of vertebrates depends largely on neural crest contribution and each subdomain of the crest-derived ectomesenchyme follows its specific genetic control. The rat small eye (rSey) involves a mutation in the Pax-6 gene and the external feature of rSey homozygous embryos exhibits craniofacial defects in ocular and frontonasal regions. In order to identify the mechanism of craniofacial development, we examined the cranial morphology and migration of cephalic crest cells in rSey embryos. The chondrocranial defects of homozygous rSey embryos primarily consisted of spheno-orbital and ethmoidal anomalies. The former defects appeared to be brought about by the lack of the eye. In the ethmoid region, the nasal septum and the derivative of the medial nasal prominence were present, while the rest of the nasal capsule, as well as the nasal and lachrymal bones, were totally absent except for a pair of cartilaginous rods in place of the nasal capsule. This suggests that the primary cranial defect is restricted to the lateral nasal prominence derivatives. Dil labeling revealed the abnormal migration of crest cells specifically from the anterior midbrain to the lateral nasal prominence in homozygous rSey embryos. Pax-6 was not expressed in the crest cells but was strongly expressed in the frontonasal ectoderm. To determine whether or not this migratory defect actually resides in environmental cues, normal midbrain crest cells from wild-type embryos were labeled with Dil and were orthotopically injected into host rSey embryos. Migration of the donor crest cells into the lateral nasal prominence was abnormal in homozygous host embryos, while they migrated normally in wild-type or heterozygous embryos. Therefore, the cranial defects in rSey homozygous embryos are due to inappropriate substrate for crest cell migration towards the lateral nasal prominence, which consistently explains the cranial morphology of homozygous rSey embryos.

Animals↗
PubMedDate not supplied

[Effect of the Tabby mutation on the dentition of mice].

The X-linked hypohidrotic ectodermal dysplasia in man leads to dental defects and is homologous to the Tabby (Ta) mutation in mouse. We currently investigate the effects of the Ta mutation on odontogenesis. The incisor germ of Ta showed an abnormal size and shape, a change in the balance between prospective crown- and root-analogue tissues and retarded cytodifferentiation. Although the enamel organ in Ta incisors was smaller, a larger proportion of the dental papilla was covered by preameloblasts-ameloblasts. The independent development of the labial and lingual parts of the enamel organ in rodent lower incisor might reflect their heterogeneous origin, as demonstrated for the upper incisor. The mandibular cheek dentition in Ta mice exhibits large variations classified in five morphotypes, based on the tooth number, shape, size and position. In Ta embryos, the mesio-distal extent of the dental epithelium was similar to that in WT, but its segmentation was altered. These morphotypes could be explained by a tentative model suggesting that 1) the positions of tooth boundaries differ in Ta and WT molars and among the Ta morphotypes; 2) the tooth patterns are determined by the distal boundary of the most mesial tooth primordium while the distal teeth take advantage of the remaining dental epithelium; 3) one tooth primordium in Ta mice might derive from adjacent parts of two primordia in WT.

Ameloblasts↗
PubMed1998

Drosophila engrailed can substitute for mouse Engrailed1 function in mid-hindbrain, but not limb development.

The Engrailed-1 gene, En1, a murine homologue of the Drosophila homeobox gene engrailed (en), is required for midbrain and cerebellum development and dorsal/ventral patterning of the limbs. In Drosophila, en is involved in regulating a number of key patterning processes including segmentation of the epidermis. An important question is whether, during evolution, the biochemical properties of En proteins have been conserved, revealing a common underlying molecular mechanism to their diverse developmental activities. To address this question, we have replaced the coding sequences of En1 with Drosophila en. Mice expressing Drosophila en in place of En1 have a near complete rescue of the lethal En1 mutant brain defect and most skeletal abnormalities. In contrast, expression of Drosophila en in the embryonic limbs of En1 mutants does not lead to repression of Wnt7a in the embryonic ventral ectoderm or full rescue of the embryonic dorsal/ventral patterning defects. Furthermore, neither En2 nor en rescue the postnatal limb abnormalities that develop in rare En1 null mutants that survive. These studies demonstrate that the biochemical activity utilized in mouse to mediate brain development has been retained by Engrailed proteins across the phyla, and indicate that during evolution vertebrate En proteins have acquired two unique functions during embryonic and postnatal limb development and that only En1 can function postnatally.

Animals↗
PubMedDate not supplied

Use of triple tissue blastocyst reconstitution to study the development of diploid parthenogenetic primitive ectoderm in combination with fertilization-derived trophectoderm and primitive endoderm.

Diploid mouse conceptuses lacking a paternal genome can form morphologically normal but small fetuses of up to 25 somites, but they invariably fail to develop beyond mid-gestation. Such conceptuses differ from normal most notably in the poor development of extra-embryonic tissues which are largely of trophectodermal and primitive endodermal origin. However, it is not clear whether the demise of diploid parthenogenetic (P) or gynogenetic (G) conceptuses is attributable entirely to the defective development of these two tissues or whether differentiation of the primitive ectoderm, the precursor of the foetus, extra-embryonic mesoderm and amnion, is also impaired by the absence of a paternal genome. Therefore, a new blastocyst reconstitution technique was used which enabled primitive ectoderm from P blastocysts to be combined with primitive endoderm and trophectoderm from fertilization-derived (F) blastocysts. One third of the 'triple tissue' reconstituted blastocysts that implanted yielded foetuses. However, all foetuses recovered on the 11th or 12th day of gestation were small and, with one exception, either obviously retarded or arrested in development. The exception was a living 44 somite specimen which is the most advanced P foetus yet recorded. Foetuses were invariably degenerating in conceptuses recovered on the 13th day. In contrast, at least 16% of control reconstituted blastocysts with primitive ectoderm as well as primitive endoderm and trophectoderm of F origin developed normally on the 13th day of gestation or to term. Hence, the presence of a paternal genome seems to be essential for normal differentiation of all 3 primary tissues of the mouse blastocyst. The P foetuses that developed from reconstituted blastocysts were so closely invested by their membranes that they often showed abnormal flexure of the posterior region of the body. Several also showed a deficiency of allantoic tissue. Therefore, the possibility that the defect in development of P primitive ectoderms resided in their extra-embryonic tissues was investigated by analysing a series of chimaeras produced by injecting them into intact F blastocysts. The foregoing anomalies were not discernible even when P cells made a large contribution to the extra-embryonic mesoderm or amnion plus umbilical cord. Furthermore, selection against P cells was no greater in extra-embryonic derivatives of the primitive ectoderm than in the foetus itself.

Animals↗
PubMed1994

Pax-6 is first expressed in a region of ectoderm anterior to the early neural plate: implications for stepwise determination of the lens.

The Pax-6 gene encodes a DNA-binding transcription factor essential to normal development of the mammalian eye. We have found that in the chick embryo, the Pax-6 gene is first expressed in a crescent-shaped region of future head ectoderm that adjoins the anterior margin of the early neural plate. As development proceeds, this region of Pax-6-positive ectoderm becomes divided into two bilateral domains. Upon contact with the optic vesicles, portions of these domains give rise to the invaginating lens placodes, which contain high levels of Pax-6 mRNA. As with mouse, rat, and zebrafish, chick Pax-6 is also expressed in the neural epithelium of the forebrain and optic vesicles. However, our results indicate that the onset of expression in the prospective head ectoderm occurs at a substantially earlier stage. Experiments involving unilateral ablation of the anterior neural plate indicate that contact with an optic vesicle is not required to maintain expression of Pax-6 in the ectoderm. Experiments in which optic vesicles have been displaced from their normal location further suggest that positioning of Pax-6 domains in the head ectoderm is independent of neighboring optic vesicles. Homozygous defects in the mouse and rat Pax-6 gene are known to cause complete failure of lens formation at the optic vesicle stage and block subsequent development of the optic cup. Our results raise the possibility that Pax-6 may be involved in the early establishment of lens-competent regions within the head ectoderm.

Amino Acid Sequence↗