Perturbation of cranial neural crest migration by the HNK-1 antibody.

The HNK-1 antibody recognizes a carbohydrate moiety that is shared by a family of cell adhesion molecules and is also present on the surface of migrating neural crest cells. Here, the effects of the HNK-1 antibody on neural crest cells were examined in vitro and in vivo. When the HNK-1 antibody was added to neural tube explants in tissue culture, neural crest cells detached from laminin substrates but were unaffected on fibronectin substrates.

Effects of isotretinoin on the behavior of neural crest cells in vitro.

Isotretinoin (13-cis-retinoic acid), an anti-acne medication, has been found to cause severe birth defects which affect the craniofacial elements, ear, heart, thymus, and central nervous system. Many of these structures receive contributions from the cranial neural crest. Here, we examine the possibility that these teratogenic effects are due to disturbances in neural crest development.

Cholinergic neurones acquire adrenergic neurotransmitters when transplanted into an embryo.

During development, cells become progressively restricted, until they reach their final phenotype. Differentiation was originally thought to be irreversible, but phenotypic plasticity has been observed in a variety of cell types, for example sympathetic neurones, the limb blastema and some glial cell types. A detailed description of the individual steps that lead to expression or reversal of phenotype is essential to understand the molecular events underlying cell differentiation.

An in vitro assay for neural crest cell migration through the somites.

Neural crest cells in the trunk of the avian embryo come into contact with the somites and neural tube during the course of their migration. However, the relationship between the somites and the early migratory routes followed by these cells is not yet completely understood. Here, we use a tissue culture assay to examine if avian neural crest cells migrate through the somites.

An antibody to a receptor for fibronectin and laminin perturbs cranial neural crest development in vivo.

Previous studies from this laboratory (M. Bronner-Fraser (1985). J.

Distribution of a putative cell surface receptor for fibronectin and laminin in the avian embryo.

The cell substratum attachment (CSAT) antibody recognizes a 140-kD cell surface receptor complex involved in adhesion to fibronectin (FN) and laminin (LM) (Horwitz, A., K. Duggan, R.

Neural tube-derived factors influence differentiation of neural crest cells in vitro: effects on activity of neurotransmitter biosynthetic enzymes.

Previously, we have demonstrated that a factor present in chick embryo extract or medium conditioned by neural tube cells supports adrenergic differentiation of some neural crest cells in vitro. These studies have been extended here to examine the effects of this factor(s) on the development of enzymes involved in neurotransmitter biosynthesis. The time course of expression of choline acetyltransferase (ChAT), a marker for cholinergic cells, and dopamine-beta-hydroxylase (DBH), a marker for adrenergic cells, was examined in neural crest cell cultures grown under three conditions: in medium containing 10% embryo extract, in medium containing 2% embryo extract, and in medium containing 2% embryo extract that was conditioned by neural tube cells (NTCM).

Analysis of the early stages of trunk neural crest migration in avian embryos using monoclonal antibody HNK-1.

The monoclonal antibody HNK-1 was used to identify neural crest cells in serial sections of avian embryos to provide a detailed description of the distribution of trunk neural crest cells. The results indicate the presence of three migratory routes in the trunk: (1) a ventral pathway through the anterior sclerotome; (2) a ventral pathway between the neural tube and the posterior sclerotome; and (3) a dorsolateral pathway between the somites and ectoderm. Neural crest cells were first seen entering the anterior half of the sclerotome at about the time the somite begins to dissociate to form the dermomyotome and sclerotome, approximately 5-10 somites rostral to the most recently formed somite.

Guidance of neural crest migration. Latex beads as probes of surface-substratum interactions.

The experiments reviewed in this chapter examine the translocation of various cell types and latex beads on a neural crest pathway. The cells and beads are implanted into the embryo via an injection technique that can be used to characterize the embryonic pathways or the injected cells themselves. The results demonstrate that postmigratory neural crest cells, undifferentiated neural crest cells, and retinal pigment epithelial cells will translocate to ventral sites after implantation.

The influence of neural tube-derived factors on differentiation of neural crest cells in vitro. I. Histochemical study on the appearance of adrenergic cells.

The neural crest gives rise to numerous derivatives including adrenergic and cholinergic neurons, supportive cells of the nervous system, and melanocytes. In tissue culture, neural crest cells explanted from both cranial and trunk regions were found to differentiate into adrenergic neuroblasts or into pigmented cells when grown in medium containing 10% chick embryo extract. When the embryo extract concentration was lowered to 2%, no catecholamine-containing cells (as assayed by formaldehyde-induced fluorescence) were detected, although pigment cells were observed.

Alterations in neural crest migration by a monoclonal antibody that affects cell adhesion.

The possible role of a 140-kD cell surface complex in neural crest adhesion and migration was examined using a monoclonal antibody JG22, first described by Greve and Gottlieb (1982, J. Cell. Biochem.

Effects of different fragments of the fibronectin molecule on latex bead translocation along neural crest migratory pathways.

Previous studies from this laboratory have utilized latex beads as probes of embryonic migratory pathways. After microinjection into embryos at the time of neural crest migration, uncoated latex polystyrene beads were found to translocate to ventral sites and to settle in the vicinity of endogenous neural crest derivatives. However, latex beads coated with fibronectin did not translocate ventrally, but remained associated with cells surrounding the implantation site.

Translocation of latex beads after laser ablation of the avian neural crest.

Previous studies from this laboratory (M.E. Bronner-Fraser, 1982, Dev.

Latex beads as probes of a neural crest pathway: effects of laminin, collagen, and surface charge on bead translocation.

In the trunk region of avian embryos, neural crest cells migrate along two pathways: dorsally just under the ectoderm, and ventrally between the neural tube and the somites. Previous work from this laboratory has shown that uncoated latex beads are able to translocate along the ventral neural crest pathway after injection into young embryos; however, beads coated with fibronectin are restricted from the ventral route ( Bronner -Fraser, M.E.

Clonal analysis of the avian neural crest: migration and maturation of mixed neural crest clones injected into host chicken embryos.

Quail neural crest cells were grown in vitro at clonal density for 7 to 10 days. Mixed neural crest colonies and clones (containing both pigmented and unpigmented cells) were implanted into the trunk region of 2 1/2-day-old host chicken embryos by a previously described injection technique (Bronner and Cohen '79). Here we describe the migratory behavior and subsequent phenotypic expression of the injected cells.