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Applications and Needs of Models for Dermatological Research
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
The wa-l mutation, which is mimicked by the TGFα knockout mouse, is a good example of a mutation that can be associated with a specific hair defect. Animal breeding and gene mapping experiments confirmed that the mutant loci are the same. Detailed work is now needed to determine why the lack of this growth factor causes the waved coat phenotype. Whether or not this is related to differential growth of portions of the follicle can now be studied. A similar approach can be taken for other mutations in which the gene product is known. For example, the study of migration of melanocytes, which are abnormal in the steel mouse mutation, can be performed to determine the migration and tracking properties of those cells. The relationship of the defect to the longevity of migrating neural crest cells, blood, and germ cells can also be determined.10
Familial Neuroblastoma
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
During embryonal development, the neural crest containing multipotent neural crest cells is formed in the dorsal part of the neural tube that will later become the brain and the spinal cord. With the ability to undergo epithelial-to-mesenchymal transition and migrate to various body locations, neural crest cells are committed to progressively restricted cell lineages, and eventually differentiate into a diversity of cell types, including the peripheral nervous system (neurons, glial cells, and Schwann cells), endocrine and paraendocrine cells, melanocytes in the epidermis, craniofacial cartilage, bone, and connective tissue [2].
The embryonic period
Published in Frank J. Dye, Human Life Before Birth, 2019
When the neural folds fuse to form the neural tube, a region of ectoderm (neuroectoderm) disappears from the surface and the balance of the ectoderm (epidermal ectoderm) closes over it. Actually, a small population of ectodermal cells disappears from the surface but is not incorporated into the neural tube; this population of cells is called the neural crest (see Figure 8.9A). Neural crest cells migrate from their initial position and give rise to a variety of structures in the developing embryo; for example, ganglia (collections of nerve cells outside the CNS), pigment cells (some of which provide us with a tan when we are exposed to the sun), and some cells (medulla) of the adrenal glands (which produce the hormones that prepare us for “fight or flight”).
Brugada syndrome
Published in Acta Cardiologica, 2021
Haarika Korlipara, Giridhar Korlipara, Srinivas Pentyala
Elizari et al. [28] proposed another mechanism behind the pathophysiology of BrS known as the neural crest hypothesis. Neural crest cells are found in extra-cardiac locations and play a fundamental role in the myocardial development of the RVOT as well as surrounding structures. Abnormal myocardialization caused by abnormal cardiac neural crest cell expression can lead to the repolarization heterogeneities underlying the phenotype of BrS. Furthermore, faster or slower migration of the cardiac neural crest cells has been demonstrated to be directly correlated with overexpression or under-expression of connexin43 (Cx43), a gap junction protein. The authors suggest that the abnormal migration of the neural crest cells would produce inhomogeneous transmural and regional Cx43 expression in the right ventricle, leading to the conduction slowing and delayed activation of the RVOT found in BrS.
Extraocular muscle hypoplasia associated with Axenfeld-Rieger syndrome
Published in Strabismus, 2021
Milo De Decker, Catherine Cassiman, Ingele Casteels, Koenraad Devriendt, Patricia Delbeke
However, in animal models, periocular neural crest cells are essential for extraocular muscle formation and organization. Both retinoic acid and Pitx2 regulate expression of muscle-specific transcription factors such as Myf5, Myog and Myod1 that are required for extraocular muscle myogenesis and survival.13 Diehl et al. demonstrated that PITX2 gene dose regulates both morphogenesis and gene expression in developing extraocular muscles. The expression of key muscle-specific transcription factor genes is regulated by PITX2 gene dose, suggesting that the level of PITX2 protein is essential for correct initiation of the myogenic regulatory cascade in extraocular muscles.14 Based on that observation, Park and colleagues propose the hypothesis that the PITX2 gene plays a role in the development of anterior segment and extraocular muscles in ARS, encoding a homeodomain transcription factor expressed in both neural crest and mesoderm during embryonic development.12
An unusual ophthalmic presentation of Wolf-Hirschhorn syndrome
Published in Ophthalmic Genetics, 2021
Gökhan Çelik, Bilge Batu Oto, Osman Kızılay, Oğuzhan Kılıçarslan, Handan Hakyemez Toptan
To our knowledge this case is the first in literature to have both colobomatous ocular cyst and optic nerve head malformations in the same eye associated with WHS. Both optic disc coloboma and morning glory anomaly occur as a result of defect in fetal fissure closure and this may suggest that, they are different presentations of the same pathology within the same spectrum of disease. The optic nerve coloboma becoming edematous with accumulation of cerebrospinal fluid may gain the appearance of morning glory anomaly. The defects are mostly caused by midline closure defects and fetal fissure closure defects due to interruption in neural crest cell motility and migration during early weeks of gestation. This unusual presentation of ocular findings in WHS indicate that optic nerve head malformations may appear in the range of ophthalmic manifestations of WHS and further studies would provide a proper classification.