Understanding limb development not only gives insights into the outgrowth and differentiation of the limb, but also has clinical relevance. Limb development begins with two paired limb buds (forelimb and hindlimb buds), which are initially undifferentiated mesenchymal cells tipped with a thickening of the ectoderm, termed the apical ectodermal ridge (AER). As a transitional embryonic structure, the AER undergoes four stages and contributes to multiple axes of limb development through the coordination of signalling centres, feedback loops, and other cell activities by secretory signalling and the activation of gene expression. Within the scope of proximodistal patterning, it is understood that while fibroblast growth factors (FGFs) function sequentially over time as primary components of the AER signalling process, there is still no consensus on models that would explain proximodistal patterning itself. In anteroposterior patterning, the AER has a dual-direction regulation by which it promotes the sonic hedgehog (Shh) gene expression in the zone of polarizing activity (ZPA) for proliferation, and inhibits Shh expression in the anterior mesenchyme. In dorsoventral patterning, the AER activates Engrailed-1 (En1) expression, and thus represses Wnt family member 7a (Wnt7a) expression in the ventral ectoderm by the expression of Fgfs, Sp6/8, and bone morphogenetic protein (Bmp) genes. The AER also plays a vital role in shaping the individual digits, since levels of Fgf4/8 and Bmps expressed in the AER affect digit patterning by controlling apoptosis. In summary, the knowledge of crosstalk within AER among the three main axes is essential to understand limb growth and pattern formation, as the development of its areas proceeds simultaneously.
Animals ; Apoptosis ; Body Patterning ; Bone Morphogenetic Proteins/biosynthesis* ; Developmental Biology ; Ectoderm/metabolism* ; Extremities/embryology* ; Fibroblast Growth Factor 10/metabolism* ; Fibroblast Growth Factors/biosynthesis* ; Gene Expression Regulation ; Hedgehog Proteins/biosynthesis* ; Homeodomain Proteins/biosynthesis* ; Mesoderm/metabolism* ; Mice ; Signal Transduction ; Wnt Proteins/biosynthesis*

Noonan syndrome (NS) and NS-related disorders (cardio-facio-cutaneous syndrome, Costello syndrome, NS with multiple lentigines, or LEOPARD [lentigines, ECG conduction abnormalities, ocular hypertelorism, pulmonic stenosis, abnormal genitalia, retardation of growth and sensory neural deafness] syndrome) are collectively named as RASopathies. Clinical presentations are similar, featured with typical facial features, short stature, intellectual disability, ectodermal abnormalities, congenital heart diseases, chest & skeletal deformity and delayed puberty. During past decades, molecular etiologies of RASopathies have been growingly discovered. The functional perturbations of the RAS-mitogen-activated protein kinase pathway are resulted from the mutation of more than 20 genes (PTPN11, SOS1, RAF1, SHOC2, BRAF, KRAS, NRAS, HRAS, MEK1, MEK2, CBL, SOS2, RIT, RRAS, RASA2, SPRY1, LZTR1, MAP3K8, MYST4, A2ML1, RRAS2). The PTPN11 (40–50%), SOS1 (10–20%), RAF1 (3–17%), and RIT1 (5–9%) mutations are common in NS patients. In this review, the constellation of overlapping clinical features of RASopathies will be described based on genotype as well as their differential diagnostic points and management.
Congenital Abnormalities ; Costello Syndrome ; Diagnosis ; Ectoderm ; Electrocardiography ; Genitalia ; Genotype ; Heart Diseases ; Humans ; Hypertelorism ; Intellectual Disability ; Lentigo ; Noonan Syndrome ; Panthera ; Protein Kinases ; Puberty, Delayed ; Pulmonary Valve Stenosis ; Thorax

Autoimmune polyendocrine syndrome type 1 (APS-1), or autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy is a rare, autosomal recessive autoimmune disease caused by a mutation of the autoimmune regulator (AIRE) gene. The main symptom triad in APS-1 comprises chronic mucocutaneous candidiasis, adrenal insufficiency, and hypoparathyroidism. Various autoimmune diseases and ectodermal abnormalities are also commonly associated with the syndrome. The treatment of APS-1 includes hormone replacement and symptom control. It is important to monitor such patients for clinical manifestations of their disease through regular follow-up. We report the case of a 10-year-old Korean girl with APS-1 due to a novel compound heterozygous mutation of the AIRE gene. This patient's main clinical manifestations were adrenal insufficiency and chronic mucocutaneous candidiasis. The patient had a previously known pathogenic variant of c.1513delG (p.Ala505ProfsTer16), and a newly discovered variant of c.1360dupC (p.His454ProfsTer50).
Adrenal Insufficiency ; Autoimmune Diseases ; Candidiasis, Chronic Mucocutaneous ; Child ; Ectoderm ; Female ; Follow-Up Studies ; Humans ; Hypoparathyroidism ; Polyendocrinopathies, Autoimmune

Myoepithelioma was recognized as a histological distinct entity by the World Health Organization (WHO) in 1991. Myoepithelial cells are believed to be of ectodermal origin. In salivary glands, the myoepithelial cells that surround the intercalated ducts are spindled, which is in contrast to the large stellate ones that envelop the acini. Myoepithelioma is a benign salivary gland tumor that consists entirely of myoepithelial cells. A 53-year-old man presented with a 1-year history of a painless mass originating from the right parotid gland. The mass grew rapidly reaching a size of approximately 6 cm. The patient had no facial paralysis. The authors performed right parotidectomy. Immunohistochemistry study of this tumor showed that it was positive for vimentin, positive for S-100, focally positive for pancytokeratin, and focally positive for p63 and that it had a Ki-67 labeling index (below 10%). Additionally, the tumor was negative for epithelial membrane antigen, negative for actin, negative for desmin, negative for CD34 and negative for anaplastic lymphoma kinase. The authors present a case of benign spindle cell myoepithelioma of the parotid gland in a 53-year-old man diagnosed after immunohistochemistry study, describing its importance, along with a brief review of the literature.
Actins ; Desmin ; Ectoderm ; Facial Paralysis ; Humans ; Immunohistochemistry ; Lymphoma ; Middle Aged ; Mucin-1 ; Myoepithelioma ; Parotid Gland ; Parotid Neoplasms ; Phosphotransferases ; Salivary Glands ; Vimentin ; World Health Organization

Ectopic sebaceous glands are found very rarely in the esophagus; heretofore, several cases have been reported. The sebaceous gland is originally a source of an endodermal origin; however, there have been controversies regarding whether the origin of the esophageal ectopic sebaceous gland is ectodermal or endodermal. Ectopic sebaceous glands of the esophagus usually do not cause symptoms; thus, they are often found incidentally on endoscopy for routine health screening. Endoscopic findings are characterized by single or multiple yellow patches or nodular lesions of various sizes, sometimes with small central openings. We report two cases of esophageal ectopic sebaceous glands found incidentally during endoscopy with magnifying endoscopic findings. The lesions were in the mid-esophagus and lower esophagus, respectively, and both endoscopic findings were similar as multiple yellowish patches or plaques. Magnifying endoscopy revealed the openings of the excretory ducts surrounded by circular microvessels in both cases.
Ectoderm ; Endoderm ; Endoscopy* ; Esophagus ; Mass Screening ; Microvessels ; Sebaceous Glands*

BACKGROUND AND OBJECTIVES: Epidermoid and dermoid cysts are benign cystic lesions, lined by ectodermal squamous epithelium. They are not common in the head and neck areas, which constitute ~7% of all cases of epidermoid and dermoid cysts. The aim of this study was to investigate the clinical characteristics of epidermoid and dermoid cysts that developed around the ear. SUBJECTS AND METHODS: The clinical records were retrospectively reviewed for patients confirmed histologically as idiopathic epidermoid and dermoid cysts of the ear from January 2011 to December 2015. RESULTS: Total 15 cases consisted of 14 epidermoid cysts and only 1 dermoid cyst. There were 11 males and 4 females (mean age of 37.8±16.8 years old). Right side was 7 cases and left was 8. The cyst was located at the lobule in 4 cases, at the ear canal in 4 cases, at the preauricular area in 4 cases, and at the postauricular area in 3 cases. In cases of epidermoid cysts, there was no significant difference in age, sex, and size according to the location. Patients with cysts on helix were younger than others. CONCLUSIONS: This study demonstrated that most cutaneous cysts developing around the ear were epidermoid cysts and there was no site preference for occurrence of epidermoid cysts.
Dermoid Cyst* ; Ear Canal ; Ear* ; Ectoderm ; Epidermal Cyst ; Epithelium ; Female ; Head ; Humans ; Male ; Neck ; Retrospective Studies

iPS cells are derived from somatic cells via transduction and expression of selective transcription factors. Both viral-integrating (like retroviral) and non-integrating (like, mRNA or protein-based) techniques are available for the production of iPS cells. In the field of dentistry, iPS cells have been derived from stem cells of apical papilla, dental pulp stem cells, and stem cells from exfoliated deciduous teeth, gingival and periodontal ligament fibroblasts, and buccal mucosa fibroblasts. iPS cells have the potential to differentiate into all derivatives of the 3 primary germ layers i.e. ectoderm, endoderm, and mesoderm. They are autogeneically accessible, and can produce patient-specific or disease-specific cell lines without the issue of ethical controversy. They have been successfully tested to produce mesenchymal stem cells-like cells, neural crest-like cells, ameloblasts-like cells, odontoblasts-like cells, and osteoprogenitor cells. These cells can aid in regeneration of periodontal ligament, alveolar bone, cementum, dentin-pulp complex, as well as possible Biotooth formation. However certain key issues like, epigenetic memory of iPS cells, viral-transduction, tumorgenesis and teratoma formation need to be overcome, before they can be successfully used in clinical practice. The article discusses the sources, pros and cons, and current applications of iPS cells in dentistry with an emphasis on encountered challenges and their solutions.
Cell Line ; Dental Cementum ; Dental Papilla ; Dentistry* ; Ectoderm ; Endoderm ; Epigenomics ; Fibroblasts ; Germ Layers ; Induced Pluripotent Stem Cells ; Memory ; Mesoderm ; Mouth Mucosa ; Periodontal Ligament ; Regeneration ; RNA, Messenger ; Stem Cells ; Teratoma ; Tooth, Deciduous ; Transcription Factors

Human embryology is the study of development from a single cell to a baby in 9 months. Implantation occurs at the end of the first week of development. The second week of development is known as the week of 2's. Gastrulation, the most characteristic event occurring in the third week, establishes three germ layers composed of ectoderm, mesoderm, and endoderm. The three germ layers and neural crest cells lead to the development of their own tissues and organs during the embryonic period, which extends from the third to the eighth week. Major congenital malformations occur in the embryonic period. The fetal period, from the third month to the day of birth, is the time for maturation of tissues and organs, and growth of the body. Because of the close relationship between embryology and congenital abnormalities, knowledge of human development is essential to assess the effects on the embryo when the mother has been exposed to teratogens. This paper briefly reviews the normal embryonic development and associated congenital malformation.
Congenital Abnormalities ; Ectoderm ; Embryology ; Embryonic Development* ; Embryonic Structures* ; Endoderm ; Female ; Gastrulation ; Germ Layers ; Human Development ; Humans* ; Mesoderm ; Mothers ; Neural Crest ; Neurulation ; Parturition ; Pregnancy ; Teratogens

No abstract available.
Ectoderm*

BACKGROUND: Both the skin and the neurologic system are derived from the ectoderm during embryogenesis, and thus patients with neurologic disorders may have accompanying dermatologic diseases. For example, seborrheic dermatitis is more frequently observed in patients with Parkinsonism and other neurologic disorders. To date, however, there has been limited review on dermatologic diseases in neurosurgical in-patients. OBJECTIVE: The purpose of this study was to characterize dermatological problems encountered in a neurosurgery unit and to compare these data to previous reports of in-patient dermatologic consultations. METHODS: A retrospective review was conducted over all in-patient dermatology consultations from the neurosurgery unit during a 3-year period. RESULTS: Of 2,770 dermatology consultations, 463 (16.7%) came from the department of neurosurgery. The most frequent age group was the 6th decade of life, and the ratio of men to women was 1.07. Consults were most frequently placed from patients with intracranial hemorrhage (23.8%). Eczema/dermatitis (36.5%; n=204) and cutaneous infections (27.0%; n=151) accounted for more than half of all dermatological consultations, followed by cutaneous adverse drug reactions (11.8%; n=66). Additionally, seborrheic dermatitis was significantly more frequent (p=0.048, odds ratio=1.96) in patients with intracranial hemorrhage. CONCLUSION: This study characterizes the distribution of skin disorders in patients admitted to the neurosurgery service based on the consultations that have been made for dermatologic evaluation. Collaboration between the neurosurgeons and dermatologists may improve the quality of patient care and help to better predict the occurrence of these conditions.
Cooperative Behavior ; Dermatitis, Seborrheic ; Dermatology ; Drug-Related Side Effects and Adverse Reactions ; Ectoderm ; Embryonic Development ; Female ; Humans ; Intracranial Hemorrhages ; Male ; Nervous System Diseases ; Neurosurgeons ; Neurosurgery ; Parkinsonian Disorders ; Patient Care ; Pregnancy ; Referral and Consultation ; Retrospective Studies* ; Skin