Methionine and neural tube closure in cultured rat embryos: Morphological and biochemical analyses

Teratology ◽  
1990 ◽  
Vol 42 (4) ◽  
pp. 437-451 ◽  
Author(s):  
Caroline N. D. Coelho ◽  
Norman W. Klein
Keyword(s):  
Neural Tube ◽  
Neural Tube Closure ◽  
Rat Embryos ◽  
Biochemical Analyses ◽  
Tube Closure

Whole Rat Embryos Require Methionine for Neural Tube Closure when Cultured on Cow Serum

1989 ◽  
Vol 119 (11) ◽  
pp. 1716-1725 ◽  
Author(s):  
Caroline N. D. Coelho ◽  
James A. Weber ◽  
Norman W. Klein ◽  
Willard G. Daniels ◽  
Thomas A Hoagland
Keyword(s):  
Neural Tube ◽  
Neural Tube Closure ◽  
Rat Embryos ◽  
Tube Closure

Immunohistochemical localisation of chondroitin sulphate proteoglycans and the effects of chondroitinase ABC in 9- to 11-day rat embryos

Development ◽  
1989 ◽  
Vol 106 (4) ◽  
pp. 787-798
Author(s):  
G. Morriss-Kay ◽  
F. Tuckett
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Chondroitin Sulphate ◽  
Neural Crest Cell ◽  
Neural Crest Cells ◽  
Neural Tube Closure ◽  
Chondroitinase Abc ◽  
Rat Embryos ◽  
Crest Cell ◽  
Tube Closure

Studies on cell behaviour in vitro have indicated that the chondroitin sulphate proteoglycan (CSPG) family of molecules can participate in the control of cell proliferation, differentiation and adhesion, but its morphogenetic functions had not been investigated in intact embryos. Chondroitin/chondroitin sulphates have been identified in rat embryos at low levels at the start of neurulation (day 9) and at much higher levels on day 10. In this study we have sought evidence for the morphogenetic functions of CSPGs in rat embryos during the period of neurulation and neural crest cell migration by a combination of two approaches: immunocytochemical localization of CSPG by means of an antibody, CS-56, to the chondroitin sulphate component of CSPG, and exposure of embryos to the enzyme chondroitinase ABC. Staining of the CS-56 epitope was poor at the beginning of cranial neurulation; bright staining was at first confined to the primary mesenchyme under the convex neural folds late on day 9. In day 10 embryos, all mesenchyme cells were stained, but at different levels of intensity, so that primary mesenchyme, neural crest and sclerotomal cells could be distinguished from each other. Basement membranes were also stained, particularly bright staining being present where two epithelial were basally apposed, e.g., neural/surface ectoderms, dorsal aorta/neural tube, prior to migration of a population of cells between them. Staining within the neural epithelium was first confined to the dorsolateral edge region, and associated with the onset of neural crest cell emigration; after neural tube closure, neuroepithelial staining was more general. Neural crest cells were stained during migration, but the reaction was absent in areas associated with migration end-points (trigeminal ganglion anlagen, frontonasal mesenchyme). Embryos exposed to chondroitinase ABC in culture showed no abnormalities until early day 10, when cranial neural crest cell emigration from the neural epithelium was inhibited and neural tube closure was retarded. Sclerotomal cells failed to take their normal pathway between the dorsal aorta and neural tube. Correlation of the results of these two methods suggests: (1) that by decreasing adhesiveness within the neural epithelium at specific stages, CSPG facilitates the emigration of neural crest cells and the migratory movement of neuroblasts, and may also provide increased flexibility during the generation of epithelial curvatures; (2) that by decreasing the adhesiveness of fibronectin-containing extracellular matrices, CSPG facilitates the migration of neural crest and sclerotomal cells. This second function is particularly important when migrating cells take pathways between previously apposed tissues.

The role of microfilaments in cranial neurulation in rat embryos: effects of short-term exposure to cytochalasin D

Development ◽  
1985 ◽  
Vol 88 (1) ◽  
pp. 333-348
Author(s):  
Gillian Morriss-Kay ◽  
Fiona Tuckett
Keyword(s):  
Neural Tube ◽  
Amorphous Material ◽  
Cytochalasin D ◽  
Neural Tube Closure ◽  
Rat Embryos ◽  
Stage Of Development ◽  
Microfilament Bundles ◽  
Short Term Exposure ◽  
Tube Closure

During the late stages of cranial neurulation in mammalian embryos, the neural epithelium becomes concave. A thick subapical band of microfilament bundles, attached to junctions which are both vertical and horizontal in orientation, can be seen by TEM. Prior to this the neural epithelium is first biconvex and then V-shaped in transverse section, microfilament bundles are absent, and the subapical junctions are only vertical in orientation. In order to determine the role of microfilaments in cranial neurulation, rat embryos were exposed to cytochalasin D (0·15 μg ml−1) for lh at three stages of development: convex neural fold stage, early concave (prior to midline apposition at the forebrain/midbrain junction: ‘preapposition’) and later concave (‘postapposition’). They were subsequently washed and cultured in addition-free medium for 5,12, 24 or 36h, then examined alive and by LM, TEM, or SEM. The degree of neural fold collapse varied with the stage of development: at the convex stage there was only slight opening out of the neural groove; early concave (preapposition) neural folds collapsed laterally to a horizontal position; later concave (postapposition) neural folds showed widening of the midbrain/hindbrain neuropore and slight neuroepithelial eversion at the anterior neuropore. Neural epithelium which had been concave prior to cytochalasin D treatment changed in structure so that the cells were broader and shorter; most of the subapical junctions were vertical in orientation, and microfilament bundles were represented either as a mass of amorphous material adjacent to the junctions, or as separated and broken filaments. Re-elevation of neural folds in ‘recovery’ cultures was accompanied by regeneration of apical microfilament bundles and horizontal junctions. Embryos which had been exposed to cytochalasin D at the convex or later concave stage of cranial neural fold development were able to complete cranial neural tube closure; none of the early-concave-stage embryos achieved apposition at the forebrain/midbrain junction, and all had major cranial neural tube defects. The results suggest that contraction of apical microfilament bundles plays an essential role in elevation of the neural folds and in the generation of concave curvature during the later stages of cranial neurulation. During the convex neural fold stage, microfilaments are important in maintaining neuroepithelial apposition in the neural groove, but are not crucial to maintenance of the convex shape. Successful formation and maintenance of the forebrain/midbrain apposition point at the appropriate time is considered to be essential for subsequent brain tube closure.

Assessment of Teratogenic Effects of Lidocaine in Rat Embryos Cultured In Vitro 

1998 ◽  
Vol 89 (6) ◽  
pp. 1553-1558 ◽  
Author(s):  
Masahiko Fujinaga
Keyword(s):  
Neural Tube ◽  
Neural Tube Closure ◽  
Control Group ◽  
Sprague Dawley ◽  
Teratogenic Effects ◽  
Rat Embryos ◽  
Slight Growth ◽  
Tube Closure ◽  
Neural Tube Closure Defects

Background Lidocaine has been reported to cause neural tube closure defects in vitro in mice at clinically relevant concentrations. However, no studies have been conducted to further investigate this potentially hazardous effect of lidocaine. This study was aimed to reassess teratogenic effects of lidocaine in vitro in rats. Methods Sprague-Dawley rat embryos were explanted at 8:00 AM on gestational day 9 and were cultured in medium containing various concentrations of lidocaine. (Embryos in the control group were cultured without lidocaine). After 50 h of culture, they were evaluated for growth size and morphology, including the neural tube closure. Results In the presence of 250 microM of lidocaine, embryos showed a increased incidence of situs inversus compared with control group but were otherwise normal. At 375 microM, embryos showed slight growth retardation but no significant morphologic abnormalities. At 500 microM, all viable embryos showed severe morphologic abnormalities. However, morphologic abnormalities were so-called nonspecific types and neural tube closure defects were not observed. Conclusions Results from the current study indicate that lidocaine causes teratogenic effects in vitro in rats only at concentrations much higher than clinically relevant concentrations. Furthermore, lidocaine did not cause neural tube closure defects at any concentrations evaluated.

Sign in / Sign up

Export Citation Format

Share Document