Cresta neural, cuarta hoja, germinativa embrionaria / Neural crest, fourth embryonary germinative leaf

RESUMEN Las células de la cresta neural son pluripotenciales y son llamadas la cuarta hoja germinativa del embrión. Con el objetivo de estructurar los referentes teóricos actualizados que sustenten la afirmación precedente y que constituirá material de estudio para los estudiantes de las Ciencias Médicas, se realizó la revisión de 28 referencias bibliográficas, de ellas 89% actualizadas. Estas células aparecen durante la neurulación y pasado este proceso transitan de epitelial a mesenquimatosa; migran siguiendo señales de la matriz extracelular a todo el cuerpo del embrión diferenciándose en tejidos disimiles. Muy vinculados en su evolución a mecanismos epigenéticos, hacen a esta población celular vulnerables a ser dañadas invocándose en la etiología de diferentes defectos congénitos y enfermedades crónicas no trasmisibles como cáncer. Como conclusión por su pluripotencialidad y por los mecanismos moleculares que distinguen su evolución son consideradas por muchos autores la cuarta hoja germinativa del embrión (AU).

SUMMARY Neural crest cells are pluripotentials, and are called the fourth germinative leaf of the embryo. With the objective of structuring the updated theoretical referents backing up the precedent affirmation that will be study material for the students of Medical Sciences, the authors reviewed 28 bibliographic references, 89 % of them updated. These cells appear during neurulation and after this process they transit from epithelial to mesenchymal; following extracellular matrix signals, they migrate to the whole embryo body differentiating themselves in dissimilar tissues. Tightly related in their evolution to epigenetic mechanisms, this cell population is very likely to be damaged and so they are invoked in the etiology of different congenital defects and noncommunicable chronic diseases like cancer. In conclusion, due to their pluripotentiality and the molecular mechanisms distinguishing their evolution, many authors consider them the embryo´s fourth germinative leaf (AU).

Understanding of Human Embryo Development for Teratogen Counselling

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.

Células de la cresta neural: Evolución, bases embrionarias y desarrollo cráneo-facial. Revisión sistemática de la literatura / Neural crest cells: Evolution, embryonic bases and craniofacial development. Systematic literature review

Las células de la cresta neural constituyen una población de células embrionarias - pluripotenciales que se diferencian desde el neuro-ectodermo y cuya aparición se constituye en una innovación evolutiva que le permitió a los vertebrados desarrollar una serie de estructuras morfo-funcionales para adaptarse de un estilo de alimentación suspensívora-filtradora a una predadora activa mucho mas eficiente. Esta revisión sistemática de la literatura describe el papel fundamental de las células de la cresta neu - ral en el desarrollo evolutivo y embrionario de las estructuras cráneo-faciales. Con este propósito se realizó una búsqueda en PubMed a través del descriptor en salud (MeSh) "neural crest" combinado con las expresiones "neurulation, evolution, embryonic and fetal development, craniofa - cialdevelopment" a través de los conectores boleanos "AND" y "+". Palabras claves: Neurulación, placa neu- ral, cresta neural, células de la cresta neural, desarrollo embrionario y fetal, desarrollo cráneo-facial.

The neural crest cells are a population of embryonic stem cells that differentiate from the neuro-ectoderm and whose appearance constitutes an evolutionary innovation allowed vertebrates develop different morpho-functional structures to adapt from asuspensivorous eating style to a predatory style, much more efficient. This systematic literature review describes the essential role of neural crest cells in the evolutionary and embryonic development of the craniofa - cial structures of the vertebrates.For this purpose we searched PubMed through the Medical Subject Headings (MeSh) "neural crest" combined with the terms "neurula - tion, evolution, embryonic and fetal develo - pment, craniofacial development" through the Boolean connectors"AND" y "+".

[ Effect of chick Embryonic Somites on Neural Rosette Formation in Mouse Embryonic Stem Cells]

The aim of the present study is to understand if EBs can generate neural rosette upon co-culture with chick embryo sornites. The mouse ES cells, line Royan Bi, were cultured in hanging drops to induce embryoid bodies [EBs] formation. Somites were isolated from the chick embryos and then embedded in alginate solution. Finally, alginate beads containing somites were co-cultured with EBs. RA was added to some EBs according to 2-12+12+ protocol Mean percentage of EBs containing early and late rosettes in somite, control and RA was 1456%, 2.6% and 0.0%, respectively and what is important to rosette formation in EBs was the preseice of neural inducing components as well as the time course of neural differentiation of EBs Chick embryonic somites can induce ES cells -derived EBs to generate rosttte structures with neuron formation capacity

Dilatación del ventrículo terminal: presentación de un caso: Revisión de la literatura / Ventricular terminalis dilation: Report of one case: Literature review

Objective: to make a bibliographical review in purpose of an infrequent case of cystic dilatation of the conus ventriculus terminalis. Description: Female patient of 34 years old, who consults for invalidating anal pain and rectal tenesmus. The MRI shows an image compatible with cystic dilatation of ventriculus terminalis. Intervention: The treatment consists in simple wide laminectomy; midline microsurgical myelotomy and marsupialization with subaracnoidal space. Following myelotomy and fenestration a significant reduction in size of the cyst was seen in MRI. Conclusion: The patient clinical response was good in relation with her initial situation (invalidating anal pain), only persists the parestesis in the right dermatomas L5-S1. This last symptom requires medical co-adyuvance (CBZ). Radiological evolution of the lesion was excellent. To 5 years only post-surgical changes are evident.

Congenital Dermal Sinuses: An Clinical Analysis of 20 Cases

OBJECTIVE: Congenital dermal sinus is a rare congenital disease that results from the failure of the neuroectoderm to separate from the surface ectoderm during the process of neurulation, where there is communication between the skin and the deeper structures. Their pathogenesis, clinical course and treatment strategy are well known. We analyze our series and compare our results with other series. METHODS: Twenty patients were diagnosed as congenital dermal sinus and confirmed pathologically from October 1986 to July 2003 at our hospital. We studied the patients' clinical manifestations, radiological findings and pathological profiles. RESULTS: Seven cases were located in the suboccipital area and 13 cases were located in the spinal area. Interestingly, 4 of 13 spinal lesion cutaneous openings were located lower than the 3rd sacral body level. 8 of 20 lesions were terminated at neural structures, 4 of 20 lesions were terminated at the intradural portion and others terminated at the extradural portion. Nine anomalies were combined with the dermal sinus, including 4 lipomas, 2 Currarino's triad, 1 encephalocele, 1 myelomeningocele and 1 diastematomyelia. Eleven patients had dermoid tumors. CONCLUSION: Congenital Dermal Sinus must be surgically removed immediately if they are diagnosed. The surgical procedure of congenital dermal sinus is complete removal, but in some cases, complete removal is impossible. In those cases, we removed all epithelial tissues. We consider sacrococcygeal dimple almost invariably have no connection with intraspinal structures. But, if other cutaneous manifestations are combined with cutaneous pits, it can communicate with the sacrococcygeal dimple.

Experimental Study on the Effects of Cabarmazepine on the Neurulation in Early Chick Embryos and Immunohistochemical Staining for Fibronectin

Teratogenic effects of carbamazepine, an anticonvulsant, on the neurulation of the explanted early chick embryos were studied utilizing the punched-out filter paper explantation and culture technique. Fresh fertilized white leghorn hen eggs were incubated for 20-30 hours in an egg incubator. The Hamburger and Hamilton stage 4-11 chick embryos were explanted using the punched-out filter paper explantation technique and cultured in the CO2 cell culture incubator for 6-10 hours. They were randomly divided into a control group and an experimental group. The experimental group was divided into five subgroups according to the carbamazepine concentrations of 20micrometer 40micrometer 100micrometer 200micrometer 400micrometer with which the Ham's F-10 culture media were treated. The morphological characteristics and the incidences of teratogenic effects on the neurulation of early chick embryos in the control and experimental groups were compared with each other using the stereomicroscope and the electron microscope. The chick embryos of the same developmental stage were selected from the control and experimental groups, and immunohistochemical staining for fibronectin was done by the double-bridge PAP method. The results were as follows. 1) Of the 41 chick embryos cultured in the Ham's F-10 media without carbamazepine, 38 embryos(92.7%) developed normally, and 3 embryos(7.3%) developed abnormally. In contrast, among the 98 embryos cultured in the carbamazepine-treated media, 54 embryos(55.1%) developed abnormally. The frequent anomalous features were deformities of the neural folds, failure of neural tube closure, derangement of somites, and developmental arrest. 2) The frequency and severity of abnormal embryos increased in dose-dependent fashion. The embryos cultured in the media treated each with 20micrometer 40micrometer 100micrometer 200micrometer 400micrometer of carbamazepine developed abnormally in 12.5%, 21.1%, 60.0%, 81.0%, 86.4% respectively. 3) The scanning electron microscopic findings in neuroepithelial cells of abnormally developed embryos were flattened and smooth cellular surface with diminished surface blebs and microvilli, and size irregularity of the cells. On transmission electron microscope, underdevelopment of intracellular microfilaments was seen, but there was no significant change in the intracellular organelle. 4) The immunohistochemical stainability of the extracellular fibronectin at the basal side of the neuroepithelium was decreased in the carbamazepine-treated embryos.

Changes of Amniotic Fluid Glucose Concentration in an Isolated Rat Embryos / 대한해부학회지

In the rat, the neural plate appears at day 9 and the neural tube closes at day 10.3. During neurulation, the neuroepithelium is exposed directly to amniotic fluid and blood circulation begins at day 10.5. Accordingly, amniotic fluid may be an important source of nutrition for normal development of the nervous system. Among many different components of amniotic fluid, glucose is known as common currency of metabolism and the developing embryo is more dependent on this. The purpose of this study is to provide basic data on the capacity of amniotic fluid as a source of glucose for neurulating rat embryos. In the first part of this paper, isolated days 10, 11 and 16 rat embryos with intact amnion were used to pursue the change of the glucose concentratons in the amniotic fluid. The day 10 embryo amniotic fluid glucose disappeared after 20 minutes, and the day 11 amniotic fluid glucose disappeared after 33 minutes. The day 16 amniotic fluid glucose showed no significant changes during 40 minutes. In the second part of this paper, the author determined the time required for glucose concentraton in the day 10 amniotic fluid to be 0 mg% at glucose free Hanks` solution. The day 10 amniotic fluid glucose disappeared afttar 10 minutes. Another embryos were exposed to glucose free Hank`s solution for 10 minutes, and switched immediately to regular Hank`s for measuring the changes of amniotic fluid glucose, that is `charging Phenomena`. During the first 15 minutes amniotic glucose was charged to nearly normal level, and after that it decreased. These changes were similar to the results from the first experiment. These results indicate that neurulating embryo has a potential for restoring its amniotic glucose concentration to the normal level rapidly. So harmful effects of hypoglycemic states may be compensated by this `charging phenomena` of amniotic fluid during neurulation.

Congenital Dermal Sinus at Thoracic Region Associated

Congenital dermal sinus (CDS) is a rare entity widely known to occur as a result of the of the failure of the neuroectoderm to separate from the cutaneous ectoderm during the process of neurulation at the third to fifth week of gestation. The lesion can occur at any level of the craniospinal axis, but are located predominantly at the lumbosacral and occipital region. CDS of thoracic region and cervical region are rare. The patient with CDS presents with meningitis and/or mass effect from the associated inclusion tumor. They are usually dermoid or epidermoid cyst. Teratoma is rarely associated with CDS. We report our experience of CDS an 11-month old boy associated with an intramedullary dermoid tumor at the thoracic region, and together we report a review of the literature.

Ultrastructural Changes in the Neurulation of Early Chick Embryos Treated with Diphenylhydantoin

Teratogenic effects of a diphenylhydantoin on the neurulation of the explanted early chick embryos were studied using the punched-out filter paper explantation technique. The 6th to 9th Hamburger and Hamilton staged chick embryos were explanted and cultured in the Ham's F-10 media treated with 15 microgram/ml, 30 microgram/ml, 60 microgram/ml, 90 microgram/ml, 120 microgram/ml of diphenylhydantoin in the CO2 incubator for 6-9 hours. The morphological chracteristics and the ultrastructural changes of the neuroepithelium of early chick embryos were compared with the control and experimental group using the stereomicroscope and the electron microscope. Of th 40 chick embryos cultured in the Ham's F-10 media without drug, 37 embryos(92.5%) developed normally and 3 embryos(7.5%) developed abnormally in 94 embryos(61.4%). The frequent anomalous features of the embryos were deformities of the neural folds in the cranial regions, failure of neural tube closure, dispersion of somites and developmental arrest. The scanning electron microscopic findings of neuropithelial cells of abnormally developed embryos were diminished surface blebs and microvilli, flattened and smooth cellular surfaces, and irregular size of cells. The transmission electron microscopic findings of neuroepithelial cells of abnormally developed embryos showed no significant changes of the development of intracellular organelles except the smooth cellular surface and mild underdevelopment of microfilaments.

The Effect of Ca++ on Neurulation of Early Chick Embryos

Chick embryos have been used widely as model systems for studies in experimental embryology and teratology. Especially early chick embryos are very useful for studies of neural tube defects. We made a try to figure out the effect of Ca++ on neurulation using Ca++ antagonist and Ca++ free media in early chick embryo, which is stage 8 by Hamburger & Hamilton classification. After 6~9 hours incubation in media treated with verapamil and media without Ca++, we observed the effects of these agents by LM and EM. All of 12 embryos incubated in Ca++ free media showed that neural tube was diffusely opened along the whole axis and other deformity was not found. The chick embryos cultured in medium treated with verapamil revealed various abnormalities in dose related manner. The case of arrest of the growth was also observed, which was not found Ca++ free media group. On scanning electron microscopic examination, the surface of neuroepithelium was flattened in embryos cultured in Ca++ free media.

The Effect of Local Anesthetics on Neurulation of Early Chick Embryos

Chick embryos have been used widely as model systems for studies in experimental embryology and teratology. Especially early chick embryos are very useful for studies of neural tube defects. Local anesthetics such as lidocaine, tetracaine and ketamine are known to inhibit the formation of microfilaments and cause neural tube defects. We made a try to figure out the effect of local anesthetics on neurulation in early chick embryo, which is stage 8 by Hamburger & Hamiliton classification. After 6~9 hours incubation in media treated with above local anesthetics, we observed the effects of these agents by LM and EM. Stage 8 chick embryos responded to local anesthetics in a dose related manner. Tetracaine showed most potent effects. Neural folds failed to make a contact, so the neural tube was left open. In high dosage, the case of no growth or little growth of embryo was also observed. On scanning electron microscopic examination, the surface of neuroepithelium was flattened in embryos treated with ketamines. On transmission electron microscopic examination. neuroepithelium of embryos cultured in ketamine showed the decrease of microfilaments and less conspicuous feature of mitochondria and rough ER(endoplasmic reticulum)'s.