Pattern formation in the facial primordia

Development ◽  
1988 ◽  
Vol 103 (Supplement) ◽  
pp. 31-40 ◽  
Author(s):  
S. E. Wedden ◽  
J. R. Ralphs ◽  
C. Tickle
Keyword(s):  
Pattern Formation ◽  
Developmental Process ◽  
Positional Information ◽  
Chick Embryos ◽  
High Density Culture ◽  
Myogenic Cells ◽  
Lower Beak ◽  
Facial Defect ◽  
Cartilage Differentiation ◽  
The Face

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.

Epithelial-mesenchymal interactions in the development of chick facial primordia and the target of retinoid action

Development ◽  
1987 ◽  
Vol 99 (3) ◽  
pp. 341-351 ◽  
Author(s):  
S.E. Wedden
Keyword(s):  
Chick Embryos ◽  
Lower Beak ◽  
Meckel’S Cartilage ◽  
Cartilage Differentiation ◽  
Recombination Experiments ◽  
Retinoid Treatment ◽  
Frontonasal Mass ◽  
And Cartilage ◽  
Facial Morphogenesis

The development of the chick face involves outgrowth of buds of tissue, accompanied by the differentiation of cartilage and bone in spatially defined patterns. To investigate the role of epithelial-mesenchymal interactions in facial morphogenesis, small fragments of facial tissue have been grafted to host chick wing buds to continue their development in isolation. Fragments of the frontonasal mass give rise to typical upper-beak-like structures: a long central rod of cartilage, the prenasal cartilage and an egg tooth. Meckel's cartilage, characteristic of the lower beak, develops from fragments of the mandible. Removal of the ectoderm prior to grafting leads to truncated development. In fragments of frontonasal mass mesenchyme only a small spur of cartilage differentiates and there is no outgrowth. The mandible is less affected; a rod of cartilage still forms but the amount of outgrowth is reduced. Retinoid treatment of chick embryos specifically affects the development of the upper beak and outgrowth and cartilage differentiation in the frontonasal mass are inhibited. The mandibles, however, are unaffected and develop normally. In order to investigate whether the epithelium or the mesenchyme of the frontonasal mass is the target of retinoid action, recombinations of retinoid-treated and untreated facial tissue have been grafted to host wing buds. Recombinations of retinoid-treated frontonasal mass ectoderm with untreated mesenchyme develop normally whereas recombinations of untreated ectoderm with retinoid-treated mesenchyme lead to truncations. The amount of outgrowth in fragments of mandibular tissue is slightly reduced when either the ectoderm or the mesenchyme has been treated with retinoids. These recombination experiments demonstrate that the mesenchyme of the frontonasal mass is the target of retinoid action. This suggests that retinoids interfere with the reciprocal epithelial-mesenchymal interactions necessary for outgrowth and normal upper beak development.

Divorce: Consequences for Children

1995 ◽  
Vol 16 (8) ◽  
pp. 306-310
Author(s):  
Robert E. Emery ◽  
Mary Jo Coiro
Keyword(s):  
Family Life ◽  
Psychological Functioning ◽  
Developmental Process ◽  
Physical Separation ◽  
The Social ◽  
The Face ◽  
Extensive Body ◽  
Time Changes ◽  
Definition Of ◽  
Divorce Consequences

An extensive body of research exists on the consequences of divorce for children. The conclusions of this research are captured by the concept of resilience, children's ability to "bounce back" in the face of stress. Most children from divorced families cannot be distinguished from children from married families on objective measures of psychological functioning, including assessments of conduct, depression, anxiety, and school performance. Nevertheless, it is clear that divorce often creates many dramatic stressors for children, including involvement in their parents' conflicts, decreased contact with one parent, strained relationships with the other parent, and economic problems. Coping with these substantial changes can tax children's emotional resources and may leave them with lingering feelings of hurt, resentment, and longing for a parental reconciliation. The concept of resilience highlights both children's ability to cope with change and some of the painful consequences of coping with unwanted changes in family life. Definition Despite its familiarity, several considerations should be noted about the definition of divorce. First, divorce is a developmental process that unfolds over time. Changes in family life typically begin long before the physical separation and continue long after the legal divorce. Second, because divorce reaches into many areas of people's lives, theorists often talk about the "legal divorce," the "emotional divorce," the "emotional divorce," the "economic divorce," and the "social divorce."

The embryonic cerebellum contains topographic cues that guide developing inferior olivary axons

Development ◽  
1997 ◽  
Vol 124 (4) ◽  
pp. 861-870 ◽  
Author(s):  
A. Chedotal ◽  
E. Bloch-Gallego ◽  
C. Sotelo
Keyword(s):  
Inferior Olive ◽  
Positional Information ◽  
Original Position ◽  
Chick Embryos ◽  
In Vitro Experiments ◽  
In Vitro System ◽  
Target Region ◽  
Inferior Olivary ◽  
Anteroposterior Polarity

The formation of the olivocerebellar projection is supposed to be regulated by positional information shared between pre- and postsynaptic neurons. However, experimental evidence to support this hypothesis is missing. In the chick, caudal neurons in the inferior olive project to the anterior cerebellum and rostral ones to the posterior cerebellum. We here report in vitro experiments that strongly support the existence of anteroposterior polarity cues in the embryonic cerebellum. We developed an in vitro system that was easily accessible to experimental manipulations. Large hindbrain explants of E7.5-E8 chick embryos, containing the cerebellum and its attached brainstem, were plated and studied using axonal tracing methods. In these cultures, we have shown that the normal anteroposterior topography of the olivocerebellar projection was acquired, even when the cerebellar lamella was detached from the brainstem and placed again in its original position. We also found that, following various experimental rotations of the anteroposterior axis of the cerebellum, the rostromedian olivary neurons still project to the posterior vermis and the caudolateral neurons to the anterior vermis, that now have inverted locations. Thus, the rotation of the target region results in the rotation of the projection. In addition, we have shown that the formation of the projection map could be due to the inability of rostromedian inferior olivary axons to grow in the anterior cerebellum. All these experiments strongly indicate that olivocerebellar fibers recognize within their target region polarity cues that organize their anteroposterior topography, and we suggest that Purkinje cells might carry these cues.

scholarly journals How is the face formed and when it goes wrong: In relation to Cleft Lip/Palate

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Fozia Khan
Keyword(s):  
Cleft Lip ◽  
Normal Development ◽  
Cleft Lip And Palate ◽  
Complex Structure ◽  
First Trimester ◽  
Facial Defect ◽  
Facial Defects ◽  
The Face ◽  
Embryonic Life ◽  
Cleft Lip Palate

The normal development of the face relies upon the correct morphogenesis of structures in utero that usually occurs within the first trimester of embryonic life. The face is a very complex structure involving many genes and factors and with it being such a crucial part of life, both physically and aesthetically and therefore mentally, its important for everything to be just right. However, when the normal process doesn’t go to plan this results in dysmorphogenesis, which cleft lip and palate (CLP) is an example of as the lip/palate doesn’t fuse together and the infant is left with a gap. Although the exact cause of CLP is unknown, it is thought to be a mixture of genetics, environment and the teratogens the mothers are exposed to within the environment. This report will demonstrate the normal development of the face for the purpose of understanding how it goes wrong, resulting in CLP. Since there is still a lot to be understood about CLP it will also shed light on recent advances in relating SHH and certain genes as a possible cause for this dysmorphogenesis. The report will also briefly look at the relation of CLP with the genes associated with syndromic and non-syndromic diseases and the different types of CLP. There are many other facial defects that are a result of dysmorphogenesis, however as CLP is one of the most common yet poorly understood facial defect, it will be the main focus of this report.

Cellular patterning of fast and slow fibres in the intermandibularis muscle of chick embryos

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 329-339 ◽  
Author(s):  
L.G. Robson
Keyword(s):  
Cell Types ◽  
Specific Pattern ◽  
Slow Muscle ◽  
Limb Bud ◽  
Muscle Fibres ◽  
Chick Embryos ◽  
Myogenic Cells ◽  
Lower Jaw ◽  
Cellular Pattern

The way in which the pattern of cell types arises during development of individual muscles was explored. The pattern of cellular differentiation resulting from the synthesis of particular fast and slow myosin heavy chains (MyHC) was investigated in the intermandibularis muscle in the lower jaw of chick embryos. The intermandibularis muscle has a proximodistal pattern of fibre type distribution. The distal region of the muscle contains a ratio of 1.5:1 fast to slow muscle fibres, which increases to > 2.5:1 in the proximal region. The intermandibularis muscle is assembled in a proximodistal sequence, with both fast and slow muscle cells differentiating within the earliest muscle and then establishing the specific pattern of cell types. This pattern is not dependent on a specific innervation source, as normal lower jaw muscles develop and the intermandibularis has the same graded cellular pattern when the mandibular primordium is grafted to the limb bud stump. Micromass cultures were used to explore the pool of potentially myogenic cells that are available to construct the muscles. Even before the muscle differentiates in vivo, both fast and slow cells are present in the primordia. These potentially myogenic cells are already distributed within the primordium in a proximodistal fashion that mimics the cellular pattern found in the muscle that develops.

scholarly journals CONTACT-MEDIATED REVERSIBLE SUPPRESSION OF MYOGENESIS

1972 ◽  
Vol 54 (1) ◽  
pp. 166-173 ◽  
Author(s):  
Mark Nameroff
Keyword(s):  
Extracellular Matrix ◽  
Ion Exchange ◽  
Active Agent ◽  
Ion Exchange Resins ◽  
Chick Embryos ◽  
Myogenic Cells ◽  
Chondrocyte Cultures ◽  
Basic Resin ◽  
Continuous Presence ◽  
Exchange Resins

Chondrocytes from the vertebral columns of 11-day chick embryos were cultured in the continuous presence of 5-bromodeoxyuridine (BUdR) Under these conditions the cells form multilayers but synthesize little extracellular matrix as determined by toluidine blue metachromasia or sulfate-35S incorporation into polysaccharide. Myogenic cells from the breast muscles of 11-day chick embryos formed myotubes when plated into BUdR-treated chondrocyte cultures. When plated on untreated chondrocyte multilayers or on multilayers which had been permitted to recover from BUdR treatment for 3 days, myogenic cells failed to form myotubes Since extracellular matrix is present in untreated chondrocyte cultures and reappears in multilayers recovering from BUdR treatment, it is suggested that extracellular matrix is the active agent in the suppression of myogenesis An attempt was made to duplicate the suppressing activity of multilayer cultures by using ion exchange resins as substrates for myogenic cells Myotubes formed on acidic and basic resin particles If extracellular matrix is the active suppressing agent, it may have to fulfill certain spatial distributional requirements before its activity is expressed

scholarly journals Analysis of the effects of Streptomyces hyaluronidase on formation of the neural tube

Development ◽  
1983 ◽  
Vol 73 (1) ◽  
pp. 1-15
Author(s):  
Gary C. Schoenwolf ◽  
Marilyn Fisher
Keyword(s):  
Spinal Cord ◽  
Extracellular Matrix ◽  
Hyaluronic Acid ◽  
Neural Tube ◽  
Neural Tube Defects ◽  
Developmental Process ◽  
Chick Embryos ◽  
In Ovo ◽  
Dorsal Midline ◽  
Specific Protease

Chick embryos at stages 8 to 9 were treated in ovo with Streptomyces hyaluronidase (SH) to determine whether neurulation occurs normally in embryos depleted of hyaluronic acid, a major component of the extracellular matrix. Open neural tube defects occurred in 60–94 % (depending on the particular enzyme batch) of the embryos treated with SH and examined after an additional 24 h of incubation. Defects were confined mainly to the spinal cord. The neural folds underwent elevation in defective regions but failed to converge and fuse across the dorsal midline. The extracellular matrix of embryos treated with SH was depleted consistently, as determined with sections stained with Alcian blue. Control experiments were done to ensure that neural tube defects were not caused by non-specific protease contamination of SH, or by digestion products of hyaluronic acid. We propose several plausible and testable mechanisms through which the extracellular matrix might influence the complex developmental process of neurulation.

Sign in / Sign up

Export Citation Format

Share Document