bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of laminin and collagens during avian neural crest development
Authors: Duband Jean-Loup , Thiery Jean Paul 
Published: April 2021

ABSTRACT
The distribution of type I, III and IV collagens and laminin during neural crest development was studied by immunofluorescence labelling of early avian embryos. These components, except type III collagen, were present prior to both cephalic and trunk neural crest appearance. Type I collagen was widely distributed throughout the embryo in the basement membranes of epithelia as well as in the extracellular spaces associated with mesenchymes. Type IV collagen and laminin shared a common distribution primarily in the basal surfaces of epithelia and in close association with developing nerves and muscles. In striking contrast with the other collagens and laminin, type III collagen appeared secondarily during embryogenesis in a restricted pattern in connective tissues.
The distribution and fate of laminin and type I and IV collagens could be correlated spatially and temporally with morphogenetic events during neural crest development. Type IV collagen and laminin disappeared from the basal surface of the neural tube at sites where neural crest cells were emerging. During the course of neural crest cell migration, type I collagen was particularly abundant along migratory pathways whereas type IV collagen and laminin were distributed in the basal surfaces of the epithelia lining these pathways but were rarely seen in large amounts among neural crest cells. In contrast, termination of neural crest cell migration and aggregation into ganglia were correlated in many cases with the loss of type I collagen and with the appearance of type IV collagen and laminin among the neural crest population. Type III collagen was not observed associated with neural crest cells during their development.
These observations suggest that laminin and both type I and IV collagens may be involved with different functional specificities during neural crest ontogeny, (i) Type I collagen associated with fibronectins is a major component of the extracellular spaces of the young embryo. Together with other components, it may contribute to the three-dimensional organization and functions of the matrix during neural crest cell migration, (ii) Type III collagen is apparently not required for tissue remodelling and cell migration during early embryogenesis, (iii) Type IV collagen and laminin are important components of the basal surface of epithelia and their distribution is consistent with tissue remodelling that occurs during neural crest cell emigration and aggregation into ganglia.
The development of animal cap cells in Xenopus: a measure of the start of animal cap competence to form mesoderm
Authors: Jones E. A. , Woodland H. R. 
Published: April 2021

ABSTRACT
Grafting, together with tissue identification by monoclonal antibodies, has been used to study the allocation of Xenopus animal cap cells to the ectodermal or mesodermal lineages. Animal cap cells become responsive at stage and lose responsiveness to mesodermal induction at, or just after, stage (depending on the batch of embryos). The ability of the vegetal yolky cells to induce mesoderm disappears between stages and 11. It is present at stage 6– and may exist before this. The emergence of competence to respond at stage , coupled with the fact that the endoderm is already capable of induction at this stage, suggests that mesodermal induction begins at this point in the intact embryo.
Role of the neural crest in development of the trabeculae and branchial arches in embryonic sea lamprey, Petromyzon marinus (L)
Authors: Langille Robert M. , Hall Brian K. 
Published: April 2021

Abstract
Lamprey embryos were obtained by artificial fertilization to ascertain the contributions made by the neural crest to the head skeleton. Early-neurula-stage embryos of Petromyzon marinus were subjected to neural crest extirpation along the anterior half from one of seven zones, raised to a larval stage at which control larvae exhibit well-developed skeletons and analysed by light microscopy for any abnormalities to the cranial and visceral skeleton. The removal of premigratory neural crest at the level of the anterior prosencephalon (zone I) and at the level of somites 6 to 8 (zone VII) had no effect on skeletal development. However, the extirpation of neural crest from the intervening regions was positively correlated with deletions/reductions to the trabeculae (basicranial elements) and to the branchial arches (viscerocranial elements). Alterations to the trabeculae (16/27 cases, or 59 %) occurred only after extirpation of zones II-V (corresponding to the posterior prosencephalon to midrhombencephalon) while alterations to the branchial arches (21/28 cases, or 75 %) occurred only after removal of neural crest from zones IH-VI (corresponding to the mesencephalon to the level of the fifth somite). Furthermore, the first three branchial arches were correlated in a majority of cases with neural crest from zone III, the next two arches with zones IV, V and VI and the last two arches with zone VI. Organs that develop within or adjacent to the area of neural crest extirpation such as the brain, notochord and lateral mesodermal derivatives were not affected. Parachordals were never altered by the operations nor were there any discernible changes to developing mucocartilage or to the prechondrogenic otic capsule. The contributions of the neural crest to the petromyzo-nid head skeleton described herein are compared with the roles of neural crest in the development of cranial and visceral skeletal elements in other vertebrates. The importance of these findings to the current hypothesis of the phylogeny of the vertebrate skeleton and the central role of the neural crest in vertebrate cephalization is discussed.
Development of macroglial cells in rat cerebellum II. An in situ immunohistochemical study of oligodendroglial lineage from precursor to mature myelinating cell
Authors: Reynolds Richard , Wilkin Graham P. 
Published: April 2021

Abstract
Using immunofluorescence with a panel of antibodies that recognize antigens expressed by oligodendroglia, the myelin-producing cells of the CNS, at different stages of differentiation from precursor to mature cell, we have investigated the development of cells of this lineage in cryostat sections of rat cerebellum. Our results are consistent with the view that glial precursors, identified by their expression of the ganglioside GD3, arise in the subependymal layers of the 4th ventricle and migrate to their final position in the cerebellum via the superior medullary velum, and to some extent the peduncles. As the cells reach their final destination they make the transition to recognizable galactocerebroside (GC)-expressing oligodendroglia, via a GD3+/GC+ intermediate. The myelin-associated protein 2′,3′-cyclic nucleotide 3′-phospho-hydrolase (CNP) appears at the same time as GC, whereas myelin basic protein (MBP) is expressed 2–3 days after GC and CNP, immediately prior to myelin formation. A very clear progression of oligodendroglial differentiation was observed from the SMV into the base of the cerebellum, up into the white matter (WM) tracts of the folia, and then away from this central white matter into the granule cell and Purkinje cell layers, and finally the molecular layer. The time delay between the expression of GC, CNP and MBP was the same for oligodendroglia in all of these layers, suggesting the presence of an intrinsic clock controlling the initial expression of these myelin components. The early appearance of CNP in oligodendroglia suggests a role for this protein in the early stages of myelinogenesis.
Vasculogenesis and angiogenesis in embryonic-stem-cell-derived embryoid bodies
Authors: Risau Werner , Sariola Hannu , Zerwes Hans-Günter , Sasse Joachim , Ekblom Peter , Kemler Rolf , Doetschman Thomas 
Published: April 2021

Abstract
Embryonic stem cells (ESC) have been established previously from the inner cell mass cells of mouse blastocysts. In suspension culture, they spontaneously differentiate to blood-island-containing cystic embryoid bodies (CEB). The development of blood vessels from in situ differentiating endothelial cells of blood islands, a process which we call vasculogenesis, was induced by injecting ESC into the peritoneal cavity of syngeneic mice. In the peritoneum, fusion of blood islands and formation of an in vivo-like primary capillary plexus occurred. Transplantation of ESC and ESC-derived complex and cystic embryoid bodies (ESC-CEB) onto the quail chorioallantoic membrane (CAM) induced an angiogenic response, which was directed by nonyolk sac endoderm structures. Neither yolk sac endoderm from ESC-CEB nor normal mouse yolk sac tissue induced angiogenesis on the quail CAM. Extracts from ESC-CEB stimulated the proliferation of capillary endothelial cells in vitro. Mitogenic activity increased during in vitro culture and differentiation of ESC. Almost all growth factor activity was associated with the cells. The ESC-CEB-derived endothelial cell growth factor bound to heparin-sepharose. The identification of acidic fibroblast growth factor (FGF) in heparin-sepharose-puri-fied material was accomplished by immunoblot experiments involving antibodies against acidic and basic FGF. We conclude that vasculogenesis, the development of blood vessels from in situ differentiating endothelial cells, and angiogenesis, the sprouting of capillaries from preexisting vessels, are very early events during embryogenesis which can be studied using ESC differentiating in vitro. Our results suggest that vasculogenesis and angiogenesis are differently regulated.
Transcription of the segment-polarity gene wingless in the imaginal discs of Drosophila, and the phenotype of a pupal-lethal wg mutation
Authors: Baker Nicholas E. 
Published: April 2021

Abstract
wingless (wg) is a segment-polarity gene in Drosophila which is related to the murine proto-oncogene inl-1. In Drosophila embryos, wg transcription defines part of each parasegment. In situ hybridization shows that wg is also expressed in the imaginal discs which give rise to the adult during metamorphosis. Transcripts are localized in the apical cytoplasm of disc cells, and accumulate in different patterns in dorsal and ventral discs. The wgCX3 mutation produces morphological defects in the adult structures derived from these imaginal discs. The results show that wg is involved in the development of the adult, as well as the embryo, but that the imaginal discs do not express this segment-polarity gene in an identical pattern to the embryonic segments.
Developmental expression of a neurofilament-M and two vimentin-like genes in Xenopus laevis
Authors: Sharpe C. R. 
Published: April 2021

Abstract
A hamster vimentin cDNA probe has been used to isolate and characterize three Xenopus laevis intermediate filament genes, named XIF1, XIF3 and XIF6. Of these, XIF6 shows 89 % homology at the amino acid level to a portion of porcine neurofilament-M. XIF6 is transcribed solely in nervous tissue of embryos, commencing at the late neural tube stage. Expression is totally dependent on an interaction between mesoderm and ectoderm during gastrulation and can be used as a marker of neural induction.
XIF1 shows 94 % homology and XIF3 83 % homology to hamster vimentin at the amino acid level over a region of the protein. Although XIF1 and XIF3 show more homology to vimentin than to any other intermediate filament gene, they have distinct temporal and spatial patterns of expression. XIF1 expression most resembles that of vimentin in higher vertebrates, being expressed in embryonic myotome and nerve cord, whilst XIF3 is unusual in that its expression is restricted predominantly to the head in tailbud embryos.
Stripes of positional homologies across the wing blade of Drosophila melanogaster
Authors: Simpson P. , Messal M. El , Prado J. Moscoso Del , Ripoll P. 
Published: April 2021

Abstract
Clones of cells mutant for shaggy transform all hairs into bristles on the wing blade of Drosophila. Different types of bristles are formed at different locations. It is shown that, although shaggy cells are unable to make a correct decision between an epidermal cell pathway and that of a sensory bristle, they are nevertheless able to respond correctly to positional cues. A compilation of many clones led to the construction of a map of positional homologies in which all of the cells in any one area will produce the same kind of bristle. The result is a series of stripes oriented perpendicular to the anteroposterior axis of the wing and parallel to the dorsoventral axis. The significance of these stripes in relation to mechanisms of pattern formation is discussed.
The application of molecular genetics to detection of craniofacial abnormality
Authors: Moore Gudrun , Ivens Alasdair , Chambers Joanna , Bjornsson Arni , Arnason Alfred , Jensson Olafur , Williamson Robert 
Published: April 2021

ABSTRACT
Congenital malformations such as secondary cleft palate can be exclusively monogenic or polygenic, but most cases have a multifactorial origin involving both environmental and genetic factors, making genetic analysis difficult. The new techniques of molecular genetics have allowed the successful chromosomal localization of mutant genes in disorders that show a simple Mendelian segregation, whether autosomal dominant (e.g. Huntington’s disease), autosomal recessive (cystic fibrosis) or X-Iinked (Duchenne muscular dystrophy). Recently, a large Icelandic family (over 280 members) with X-linked secondary cleft palate and ankyloglossia (tongue-tied) has been used as a model to localize the mutant gene associated with this craniofacial clefting. The gene has been sub-chromosomally localized to Xql3–q21.1, using anonymous probe DXYS1; a LOD score of 3· 07 was obtained.
We are preparing cosmid libraries from DNA from mouse cell lines containing only the relevant part of the human X chromosome, introduced by chromosome-mediated gene transfer. Cosmids that contain human X-chromosome sequences will be isolated and analysed for overlapping sequences and RFLPs (restriction fragment length polymorphisms) and the regions further defined by pulsed-field gel electrophoresis and the identification of coding sequences. This should give data on the location and structure of a gene involved in the craniofacial development of the human palatine shelves. This gene, and its protein product, will identify one component of the pathway that causes nonfusion of the palate. In the long term, the understanding of the expression of this sex-linked gene for secondary cleft palate and ankyloglossia will provide a model for the molecular identification of other genes regulating processes in craniofacial development whose expression is hidden in phenotypic, polygenic complexity.
Pattern formation in the facial primordia
Authors: Wedden S. E. , Ralphs J. R. , Tickle C. 
Published: April 2021

ABSTRACT
Pattern formation is the developmental process that leads to the spatial ordering of cell differentiation. We have explored the problem of pattern formation in the development of the face of chick embryos. At early stages, the developing face consists of a series of small buds of tissue, the facial primordia that encircle the primitive mouth. The concepts of positional information provide a framework for considering how the patterns of differentiated cells are generated in the face. We suggest that the cranial neural crest cells must first be informed to which facial primordium they belong and then of their position within that primordium.
The cells of the early primordia appear indistinguishable. However, when the mesenchyme cells are placed in high-density culture, cartilage differentiates. The extent and pattern of cartilage differentiation is characteristic for the cell population of each facial primordium. Myogenic cells also differentiate in the cultures, but the proportion of myogenic cells is independent of the extent of chondrogenesis. Within the facial primordia, a set of epithelial-mesenchymal interactions appears to be required for outgrowth and pattern formation along the proximodistal axis of the chick beaks. In culture, face epithelium locally inhibits cartilage differentiation and suggests that another set of epithelial-mesenchymal interactions may be involved in cell patterning. The mechanisms involved in specifying the mediolateral axis of the face, for example, the midpoint of the upper beak, are not known.
Vitamin A derivatives, collectively known as retinoids, affect the development of the face of chick embryos and lead to a specific facial defect. Upper beak development is inhibited but the lower beak develops normally. The response to retinoids could be related to the specification of cells to belong to the facial primordium that will form the upper beak. Alternatively, retinoids may interfere with positional cues that operate to inform cells of their position within that primordium.
Control of pathfinding by the avian trunk neural crest
Authors: Erickson Carol A. 
Published: April 2021

ABSTRACT
We have determined the pathways taken by the trunk neural crest of quail and examined the parameters that control these patterns of dispersion. Using antibodies that recognize migratory neural crest cells (HNK-1), we have found that the crest cells take three primary pathways: (1) between the ectoderm and somites, (2) within the intersomitic space and (3) through the anterior somite along the basal surface of the myotome.
The parameters controlling dispersion patterns of neural crest cells are several. The pathways are filled with at least two adhesive molecules, laminin and fibronectin, to which neural crest cells adhere tenaciously in culture. The pattern of migration through the somite may be accounted for in part by the precocious development of the basal lamina of the dermamyotome in the anterior half of the somite; this basal lamina contains both fibronectin and laminin and the neural crest cells prefer to migrate on it. In contrast, the regions into which the crest cells do not invade are filled with relatively nonadhesive molecules such as chondroitin sulphate. Some of the pathways are filled with hyaluronic acid, which stimulates the migration of neural crest cells when they are cultured in three-dimensional gels, presumably by opening spaces. Neural crest cells are also constrained to stay within the pathways by basal laminae, which act as barriers and through which crest cells do not go. Therefore, crest pathways are probably defined by several redundant factors.
The directionality of crest cell migration is probably due to contact inhibition, which can be demonstrated in tissue culture. Various grafting experiments have suggested that chemotaxis and haptotaxis do not play a role in controlling the dispersion of the crest cells away from the neural tube.
We have documented the extraordinary ability of neural crest cells to disperse in the embryo, even when they are grafted into sites in which they would normally not migrate. We have evidence that the cells’ production of plasminogen activator, a proteolytic enzyme, and also the minimal tractional force that crest cells exert on the substratum as they migrate, contribute to this migratory ability.
Accumulation of collagen III at the cleft points of developing mouse submandibular epithelium
Authors: Nakanishi Yasuo , Nogawa Hiroyuki , Hashimoto Yoko , Kishi Jun-Ichi , Hayakawa Taro 
Published: April 2021

ABSTRACT
The distribution of collagens I, III, IV and V was studied by immunoperoxidase staining of early developing mouse submandibular glands. Collagen I was always present in the extracellular matrices of the mesenchyme and at the epithelial-mesenchymal interfaces of the 12-day gland with no clefts and of the 13-day gland with a few definite clefts. Collagen III was found in a similar fashion to that of collagen I in the mesenchyme, but the distribution at the epithelial-mesenchymal interfaces was very different. In the mid 12-day gland with a round lobule, collagen III was distributed at every slightly indented site of basal epithelial surfaces. At the late 12-day stage, a few initial signs of cleft appeared on the surface, at which accumulation of collagen III became evident. Intense immunoreaction of collagen III in the early 13-day gland was seen at the bottom of every narrow cleft. No specific accumulation of collagens IV and V was observed in clefts of the late 12-day and early 13-day glands.
Staining of collagen III in the 12-day gland cultured for 10 h in the presence of bovine dental pulp collagenase inhibitor, which has been shown to stimulate cleft initiation, was very prominent at the bottom of every narrow cleft. These observations suggest that collagen III works as a key substance for either in vitro or in vivo cleft initiation of the mouse embryonic submandibular epithelium.
Spatial- and temporal-restricted pattern for amelogenin gene expression during mouse molar tooth organogenesis
Authors: Snead Malcolm L. , Luo Wen , Lau Eduardo C. , Slavkin Harold C. 
Published: April 2021

ABSTRACT
Position- and time-restricted amelogenin gene transcription was analysed in developing tooth organs using in situ hybridization with asymmetric complementary RNA probes produced from a cDNA specific to the mouse 26×103Afr amelogenin. In situ analysis was performed on developmentally staged fetal and neonatal mouse mandibular first (MO and maxillary first (M1) molar tooth organs using serial sections and three-dimensional reconstruction. Amelogenin mRNA was first detected in a cluster of ameloblasts along one cusp of the M1 molar at the newborn stage of development. In subsequent developmental stages, amelogenin transcripts were detected within foci of ameloblasts lining each of the five cusps comprising the molar crown form. The number of amelogenin transcripts appeared to be position-dependent, being more abundant on one cusp surface while reduced along the opposite surface. Amelogenin gene transcription was found to be bilaterally symmetric between the developing right and left M1 molars, and complementary between the M1 and M1 developing molars; indicating position-restricted gene expression resulting in organ stereoisomerism. The application of in situ hybridization to forming tooth organ geometry provides a novel strategy to define epithelial-mesenchymal signal(s) which are believed to be responsible for organ morphogenesis, as well as for temporal- and spatial-restricted tissue-specific expression of enamel extracellular matrix.
Early innervation of the metanephric kidney
Authors: Sariola H. , Holm K. , Henke-Fahle S. 
Published: April 2021

AbstractDuring kidney differentiation, the nephrogenic mesenchyme converts into renal tubules and the ureter bud branches to form the collecting system. Here we show that in the early undifferentiated kidney rudiment there is a third cell type present. In whole-mount preparations of cultured undifferentiated metanephric kidneys, neurones can be detected by immunohistochemical means with antibodies against the neurofilament triplet, 13AA8, and against neuronal cell surface gangliosides, Q211. Clusters of neuronal cell bodies can be seen in the mesenchyme close to the ureter bud. The terminal endings of neurites are found around the mesenchymal condensates that later become kidney tubules. A similar distribution of neurites can be revealed in tissue sections of kidney grafts growing in the chicken chorioallantoic membranes. In primary cultures of the ureter bud cells, neurones are con-stantly present. In another report, we have shown that, in experimental conditions, neurones are in-volved in regulation of kidney morphogenesis. The present results raise the possibility that neurones of the metanephric kidney may have this function in vivo as well.