The two sites of fusion of the neural folds and the two neuropores in the human embryo

OʼRahilly, Ronan; Müller, Fabiola

doi:10.1002/tera.10007

Cited by 136 publications

(97 citation statements)

References 30 publications

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“…For example, the longitudinal axis of an embryo, whether fish, chick, mouse or human, is rostrocaudal rather than anteroposterior. Usages such as anterior neural plate for the rostral part of the neural plate are undesirable, and the neuropores are rostral (or cranial) and caudal [Nomina embryologica, 1989;O'Rahilly and Müller, 2002]. Finally, the word primitive, with The term prochordal rather than prechordal was used.…”

Section: Discussionmentioning

confidence: 99%

The Prechordal Plate, the Rostral End of the Notochord and Nearby Median Features in Staged Human Embryos

Müller

OʼRahilly

2003

Cells Tissues Organs

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The enigmatic structure known as the prechordal plate and also the precursors of the notochord were reassessed in 101 human embryos of stages 8–14; 36 were controlled by precise graphic reconstructions. Various measurements were made and the appearance of median structures was tabulated. The prechordal plate, which has been unequivocally found first at stage 7, is usually detectable at stage 8 as a highly developed mesendodermal mass in contact with the floor of the neural groove. At stages 9 and 10 the plate is related to neuromere D1. Cellular migration laterad at stages 9–11 gives rise to the bilateral premandibular condensations, which are lateral to the adenohypophysial primordium, and at stages 13 and 14 these condensations are closely related to the future tentorium cerebelli. The notochordal process is first visible at stage 7, and its dorsal part constitutes the notochordal plate at stage 8. At stages 8–10 the notochordal and prechordal plates appear continuous, but they are distinguishable histologically. The notochordal plate becomes intercalated in the endoderm of the foregut and begins to give rise to the notochord at stages 10 and 11. Bifurcation occurs rostrally at stage 12: the dorsal limb disappears, whereas the ventral limb is the definitive continuation. The topographical relationships of the prechordal and notochordal plates, the notochord, the adenohypophysis, and the oropharyngeal membrane are documented. Definitions and pertinent remarks on terminology are included, comparative data are considered, and the origin and derivatives of the prechordal plate are discussed. In addition to giving rise to external ocular muscles, the possibility of contributions to the heart and the tentorium cerebelli is raised. The importance of the plate in the development of the forebrain, as well as in the production of median anomalies such as holoprosencephaly and cyclopia, is stressed.

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Section: Discussionmentioning

confidence: 99%

The Prechordal Plate, the Rostral End of the Notochord and Nearby Median Features in Staged Human Embryos

Müller

OʼRahilly

2003

Cells Tissues Organs

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“…During neural tube closure, the neural folds are brought together at the dorsal midline to form the neural tube and adhere to each other. In humans and other mammals, closure of the neural tube is thought to be initiated by sites of fusion at more than one place along the anterior-posterior axis (Van Allen et al 1993;O'Rahilly and Muller 2002;Sulik et al 1998). The first fusion occurs in humans when there are 4-6 somite pairs present, at Carnegie stage (C) 10, and closure continues though C12 with the closure of the caudal neuropore (O'Rahilly and Muller 2002).…”

Section: Introductionmentioning

confidence: 99%

SNPs in the neural cell adhesion molecule 1 gene (NCAM1) may be associated with human neural tube defects

et al. 2005

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Neural tube defects (NTDs) are common birth defects, occurring in approximately 1/1,000 births; both genetic and environmental factors are implicated. To date, no major genetic risk factors have been identified. Throughout development, cell adhesion molecules are strongly implicated in cellcell interactions, and may play a role in the formation and closure of the neural tube. To evaluate the role of neural cell adhesion molecule 1 (NCAM1) in risk of human NTDs, we screened for novel single-nucleotide polymorphisms (SNPs) within the gene. Eleven SNPs across NCAM1 were genotyped using TaqMan. We utilized a family-based approach to evaluate evidence for association and/or linkage disequilibrium. We evaluated American Caucasian simplex lumbosacral myelomeningocele families (n=132 families) using the family based association test (FBAT) and the pedigree disequilibrium test (PDT). Association analysis revealed a significant association between risk for NTDs and intronic SNP rs2298526 using both the FBAT test (P=0.0018) and the PDT (P=0.0025). Using the HBAT version of the FBAT to look for haplotype association, all pairwise comparisons with SNP rs2298526 were also significant. A replication study set, consisting of 72 additional families showed no significant association; however, the overall trend for overtransmission of the less common allele of SNP rs2298526 remained significant in the combined sample set. In addition, we analyzed the expression pattern of the NCAM1 protein in human embryos, and while NCAM1 is not expressed within the neural tube at the time of closure, it is expressed in the surrounding and later in differentiated neurons of the CNS. These results suggest variations in NCAM1 may influence risk for human NTDs.

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“…These include: 1) closure of neuropores and separation of the neural tube from amniotic cavity, 2) appearance of the neuromeres and subdivision of the neural crest, 3) presence of the five chief parts of the brain, 4) formation of the cerebral hemispheres, 5) formation of the nuclei of the cranial nerves in the brain stem, 6) development of the cranial nerves ganglia, and 7) appearance of the branches of the cranial nerves. In humans, only two sites of fusion of the neural folds and two neuropores are found and the closure of the anterior neuropore is bidirectional [25,26]. It proceeds simultaneously from a dorsal lip (midbrain -diencephalon border) and from a ventral lip (telencephalic region).…”

Section: Discussionmentioning

confidence: 99%

Early development of the facial nerve in human embryos at stages 13–15

et al. 2015

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The two sites of fusion of the neural folds and the two neuropores in the human embryo

Cited by 136 publications

References 30 publications

The Prechordal Plate, the Rostral End of the Notochord and Nearby Median Features in Staged Human Embryos

The Prechordal Plate, the Rostral End of the Notochord and Nearby Median Features in Staged Human Embryos

SNPs in the neural cell adhesion molecule 1 gene (NCAM1) may be associated with human neural tube defects

Early development of the facial nerve in human embryos at stages 13–15

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