Ultrastructural studies of amphibian neural fold fusion

Mak, Linda L.

doi:10.1016/0012-1606(78)90039-8

Cited by 34 publications

(16 citation statements)

References 21 publications

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“…Once cell-cell contact has been made,ceilsurface carbohydrates markedly decrease as neurulation is completed. The resultsofothercell surface labelingexperiments-concanavalin A(con-A)-hemocyanin, Alcian blue, lanthanum nitrate-ha ve also identi fied the presence of carbohydrates on the neuroepithelium [15][16][17][18], 012 Lee et al [19] reported that labeled Con-A binds to the apical surface of the closing neuroectoderm, alters the surface membrane activity and, in a high percentage of embryos, interrupts the process of neurulation.…”

Section: Initial Morphological Events In Neural Tube Closurementioning

confidence: 99%

Role of Complex Carbohydrates and Neurulation

McLone¹,

Knepper²

1985

Pediatr Neurosurg

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Extracellular and cell-coat complex carbohydrates play a major role in critical cellular functions, e.g., cell recognition and cell-to-cell adherence, which are involved in neurulation. To date, available evidence suggests that neurulation is a combination of intercellular and extracellular biochemical and morphological events which are under the direction of the genome. To define the carbohydrate components that are essential to neurulation, normal C-57 and abnormal splotch (Sp/Sp) mouse embryos were studied using fluorescein-labeled lectins and computer-aided microspectrophotometric analysis of hyaluronate lyase and chondroitin ABC lyase-sensitive Alcian blue staining. Preliminary results of these studies indicate that the neuroepithelium of the splotch Sp/Sp mutant, a genetic model of a primary neural tube defect, is characterized by alterations in the type and amount of glycoconjugates and in the concentration of individual glycosaminoglycans. This review of mammalian neurulation discusses the importance of complex carbohydrates on the cell surface of the neuroepithelium of the closing neural fold.

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Section: Initial Morphological Events In Neural Tube Closurementioning

confidence: 99%

Role of Complex Carbohydrates and Neurulation

McLone¹,

Knepper²

1985

Pediatr Neurosurg

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“…Several studies have shown that similar extracellular matrices exist, covering the apical surface of epithelial cells in various embryonal primordia at moments prior to epithelial fusion, for example, in the nasal folds [Gaare and Langman, 1977;Burk et al, 1979], the otic vesicle [Sinning and Olson, 1988], the lens vesicle [Gato et al, 2001] and the palate [Greene and Kochhar, 1974;Pratt and Hassell, 1975;Souchon, 1975]. In this regard, it has been shown that these neuroepithelial cells on the tip of the neural folds or other primordia have ultra-structural characteristics compatible with active secretion processes occurring before fusion [González Santander and Martínez Cuadrado, 1976;Mak, 1978;Rovasio and Monis, 1981;Sinning and Olson, 1988;Alonso et al, 1998a].…”

Section: Discussionmentioning

confidence: 99%

“…Yet the relevance of such mechanisms needs to be supported by experimental evidence. At brain level, one of the changes described as occurring prior to fusion affects both the surface of the cells about to fuse (the appearance of cytoplasmic prolongations of the same type as the pseudopodia and extracellular vesicles), as well as their internal morphology (the appearance of many apical intracellular vesicles) [Mak, 1978]; similar changes have been reported during palatal fusion [Souchon, 1975;Schupbach et al, 1983;Taya et al, 1999;Martínez-Álva-rez et al, 2000a, b]. Furthermore, there has been a report on an extracellular matrix interposed between the apical neural folds immediately prior to contact between the neural folds on both sides [Mak, 1978;Sadler, 1978].…”

Section: Introductionmentioning

confidence: 99%

“…At brain level, one of the changes described as occurring prior to fusion affects both the surface of the cells about to fuse (the appearance of cytoplasmic prolongations of the same type as the pseudopodia and extracellular vesicles), as well as their internal morphology (the appearance of many apical intracellular vesicles) [Mak, 1978]; similar changes have been reported during palatal fusion [Souchon, 1975;Schupbach et al, 1983;Taya et al, 1999;Martínez-Álva-rez et al, 2000a, b]. Furthermore, there has been a report on an extracellular matrix interposed between the apical neural folds immediately prior to contact between the neural folds on both sides [Mak, 1978;Sadler, 1978]. The presence of this surface coat material in the fusion of the neural folds has been shown to be a phylogenetic constant, having been described in the embryos of amphibians [Rice and Moran, 1977;Mak, 1978], birds [Lee et al, 1976;Rovasio and Monis, 1981;Schoenwolf and Fisher, 1983] and mammals [Sadler, 1978].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, there has been a report on an extracellular matrix interposed between the apical neural folds immediately prior to contact between the neural folds on both sides [Mak, 1978;Sadler, 1978]. The presence of this surface coat material in the fusion of the neural folds has been shown to be a phylogenetic constant, having been described in the embryos of amphibians [Rice and Moran, 1977;Mak, 1978], birds [Lee et al, 1976;Rovasio and Monis, 1981;Schoenwolf and Fisher, 1983] and mammals [Sadler, 1978].…”

Section: Introductionmentioning

confidence: 99%

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Chondroitin Sulphate-Mediated Fusion of Brain Neural Folds in Rat Embryos

Alonso

Moro

Martín

et al. 2008

Cells Tissues Organs

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Previous studies have demonstrated that during neural fold fusion in different species, an apical extracellular material rich in glycoconjugates is involved. However, the composition and the biological role of this material remain undetermined. In this paper, we show that this extracellular matrix in rat increases notably prior to contact between the neural folds, suggesting the dynamic behaviour of the secretory process. Immunostaining has allowed us to demonstrate that this extracellular matrix contains chondroitin sulphate proteoglycan (CSPG), with a spatio-temporal distribution pattern, suggesting a direct relationship with the process of adhesion. The degree of CSPG involvement in cephalic neural fold fusion in rat embryos was determined by treatment with specific glycosidases.In vitro rat embryo culture and microinjection techniques were employed to carry out selective digestion, with chondroitinase AC, of the CSPG on the apical surface of the neural folds; this was done immediately prior to the bonding of the cephalic neural folds. In all the treated embryos, cephalic defects of neural fold fusion could be detected. These results show that CSPG plays an important role in the fusion of the cephalic neural folds in rat embryos, which implies that this proteoglycan could be involved in cellular recognition and adhesion.

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Disruption of proteoglycans in neural tube fluid by β-D-xyloside alters brain enlargement in chick embryos

et al. 1998

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Following neurulation, the anterior end of the neural tube undergoes a dramatic increase in size due mainly to the enlarging of the brain cavity. This cavity is filled with so-called neural tube fluid (NTF), whose positive pressure has been shown to play a key role in brain morphogenesis. This fluid contains a water-soluble matrix, rich in chondroitin sulfate (CS), which has been proposed as an osmotic regulator of NTF pressure genesis. The purpose of the present study is to observe the influence of CS on NTF osmolality and its relation to NTF hydrostatic pressure and brain expansion. NTF was obtained by means of microaspiration from the mesencephalic cavity of chick embryos. The osmolality of NTF between H.H. stages 20 and 29 was measured on the basis of its cryoscopic point. CS synthesis was disrupted by using beta-D-xyloside and the induced variations in brain volume were measured by means of morphometry. We also measured the variations in NTF osmolality, hydrostatic pressure, and the concentration of CS and sodium induced by means of beta-D-xyloside. Our data reveal that, at the earliest stages of development analyzed, variations in NTF osmolality show a characteristic pattern that coincides with the developmental changes in the previously described fluid pressure. Chick embryos treated with beta-D-xyloside, a chemical that disrupts CS synthesis, displayed a notable increase in brain volume but no other apparent developmental alterations. Morphometric analysis revealed that this increase was due to hyperenlargement of the brain cavity. Beta-D-xyloside brings about specific changes in the biochemical composition of NTF, which entails a large increase in CS concentration, mainly in the form of free chains, and in that of sodium. As a result, the fluid's osmolality and brain intraluminal pressure increased, which could account for the increase in size of the brain anlage. These data support the hypothesis that the intraluminal pressure involved in embryonic brain enlargement is directly dependent on NTF osmolality, and that the concentrations of CS and its associated microions could play a key role in the regulation of this process.

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Ultrastructural studies of amphibian neural fold fusion

Cited by 34 publications

References 21 publications

Role of Complex Carbohydrates and Neurulation

Role of Complex Carbohydrates and Neurulation

Chondroitin Sulphate-Mediated Fusion of Brain Neural Folds in Rat Embryos

Disruption of proteoglycans in neural tube fluid by β-D-xyloside alters brain enlargement in chick embryos

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