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  • 1
    Electronic Resource
    Electronic Resource
    Atavisms and atavistic mutations (1995)
    [s.l.] : Nature Publishing Group
    Nature genetics 10 (1995), S. 126-127 
    Details
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Atavisms — the reappearance of ancestral characteristics in individual members of a species — serve to remind us that the genetic and developmental information originally used in the production of such characteristics has not been lost during evolution but lies quiescent within the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/ng0695-126
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  • 2
    Electronic Resource
    Electronic Resource
    Role of the neural crest in development of the cartilaginous cranial and visceral skeleton of the medaka, Oryzias latipes (Teleostei) (1988)
    Springer
    Anatomy and embryology 177 (1988), S. 297-305 
    Details
    ISSN: 1432-0568
    Keywords: Teleost ; Neural crest ; Development ; Chondrocranium ; Viscerocranium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neural crestectomies were performed on neurula stage medaka embryos to remove neural crest with tungsten needles from one of five anteriorly located zones. The embryos were allowed to develop to stage 35 (immediately posthatching) larvae, then cleared and stained for cartilage. An analysis of changes to the head skeletons indicated that most of the anterior neurocranium and the entire viscerocranium received neural crest contributions during development. The elements involved included; the lamina orbitonasalis of the nasal capsule, the trabeculae, Meckels' cartilage and the quadrate of the lower jaw, the pterygoid process, the orbital cartilages and the epiphyseals of the neurocranial roof, as well as all the elements of the hyoid and branchial arches. By further analysis of only those neural crest ablations which produced alterations to the head skeleton, the neural crest cells which contributed to the development of each element were mapped. They originated principally, from one of three regions; the mesencephalon (second most anterior zone removed, number II), the preotic rhombencephalon (zone III), or the postotic rhombencephalon (zone IV). Neural crest from the level of the prosencephalon (zone I) was not chondrogenic nor was neural crest from the fifth region (zone V) which extended beyond the 5th to about the 8th or 10th somite and marked the anterior end of trunk neural crest. The data are discussed and are found to be consistent with the results from other vertebrates and support the central role of the neural crest in the development and evolution of the vertebrate bead skeleton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315836
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  • 3
    Electronic Resource
    Electronic Resource
    Chondrogenic cell differentiation from membrane bone periostea (1997)
    Springer
    Anatomy and embryology 196 (1997), S. 349-362 
    Details
    ISSN: 1432-0568
    Keywords: Key words Chondrogenesis ; Osteogenesis ; Intramembranous bone ; Cartilage ; Cell differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Most craniofacial membrane bones are derived from neural crest (NC) cells. Interaction between NC cells and epithelium, and cellular condensation, are two major events that lead NC cells to become osteoblasts that deposit membrane bone. Unlike endochondral bone, membrane bone formation is not preceded by cartilage formation in normal development. However, chondrogenic potential in membrane bone is evidenced by several cartilage-associated phenomena in vivo. Furthermore, in vitro, periosteal cells of some membrane bones express cartilage phenotype gene products and even differentiate into chondrocytes. Hence, membrane bone periosteal cells can undergo chondrogenic differentiation. The precursor of chondrogenic cells in membrane bone is not clear: chondrocytes were proposed to arise from unipotential chondroprogenitor cells, bi- or multipotential progenitor cells, or differentiated osteogenic cells. There is experimental support for each, but studies on clonal and cell cultures provided more support for a common precursor of both chondro- and osteogenic cells. Moreover, in periostea, chondrogenesis probably arises from a differentiated cell type. Membrane bone formation in periostea may include a transient cell stage that is able to undergo both osteo- and chondrogenesis. Osteogenesis would be the normal pathway, but chondrogenesis can be evoked in certain microenvironments. It is not known whether microenvironmental factors trigger chondrogenesis through a universal molecular mechanism, nor is the molecule that triggers chondrogenesis known. Expression of neural cell adhesion molecule (NCAM) is down-regulated during commitment of periostal cells for secondary chondrogenesis, suggesting a possible regulatory role for NCAM in the alternative differentiation pathways of periosteal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050104
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  • 4
    Electronic Resource
    Electronic Resource
    Skull development during anuran metamorphosis (1988)
    Springer
    Anatomy and embryology 178 (1988), S. 219-227 
    Details
    ISSN: 1432-0568
    Keywords: Thyroid hormone ; Osteogenesis ; Skull ; Metamorphosis ; Amphibian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We examined the role of thyroid hormone (TH) in mediating cranial ossification during metamorphosis in the Oriental fire-bellied toad, Bombina orientalis. Exogenous T3 (3,3′,5-triiodo-L-thyronine) was administered in three treatment dosages (0.025, 0.25, and 2.5 μg) plus a control dosage via plastic micropellets implanted within the dermis of tadpoles of three Gosner developmental stages: 28/29, 30/31, 32/33. Tadpoles were recovered after 2, 4, 6, and 8 d, and scored for the presence of three bones —median parasphenoid and paired frontoparietals and exoccipitals—as seen in cleared-and-stained, whole-mount preparations. T3 induced precocious ossification in both a stage-dependent and a dosage-dependent manner; stage dependence corresponded precisely with the degree of osteogenic differentiation at the time of hormone administration. Precocious ossification thus was due to the T3-promoted growth and calcified matrix deposition of these centers. Differential TH sensitivity among osteogenic sites may underlie both the temporal cranial ossification sequences characteristic of metamorphosing amphibians as well as sequence differences commonly observed among taxa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318225
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  • 5
    Electronic Resource
    Electronic Resource
    Response of host embryonic chicks to grafts of additional adrenal glands (1970)
    Springer
    Cell & tissue research 108 (1970), S. 1-16 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal ; Avian ; Ultrastructure ; Graft ; Compensatory hypertrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the developing adrenal gland of the chick has been studied over the embryonic period 10 to 18 days. Cortical cells occur in double-rowed strands, are loosely attached in early development but more firmly attached later in development. Hypertrophy of mitochondria, endoplasmic reticulum, golgi body, lipid and vacuoles increases with increasing age. Two cell types (designated “Dark” and “Light”) were present at 17 days of incubation. Their significance is discussed. Medullary cells occur as single cells at 10 days but more usually in groups by 18 days. Catecholamine-containing granules are a prominent feature of the medullary cells, at all ages. Two cell types could be distinguished in the medulla at 17 days of incubation. These may represent adrenalin and noradrenalin-containing cells. Changes in the ultrastructure of host adrenal glands after exposure to an 18 day adrenal gland, grafted onto the host chorio-allantoic membrane at 8 days, were studied. The chief response within the cortex of the host involved retardation of organelle hypertrophy, so that 17 day hosts resembled 14 day controls. More light cells were seen in the host than in the control cells. The medullary tissue of the host was also retarded in development and the release of catecholamine-containing granules inhibited. The significance of these observations in relation to compensatory hypertrophy within the host is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335939
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  • 6
    Electronic Resource
    Electronic Resource
    Grafting of organs and tissues to the chorioallantoic membrane of the embryonic chick (1978)
    Springer
    Methods in cell science 4 (1978), S. 881-884 
    Details
    ISSN: 1573-0603
    Keywords: chorioallantoic membrane ; grafting ; organs ; differentiation ; morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00918539
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  • 7
    Electronic Resource
    Electronic Resource
    Paralysis and growth of the musculoskeletal system in the embryonic chick (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 45-56 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Avian embryos can be completely paralyzed by injection of neuromuscular-blocking agents. We used a single injection of decamethonium iodide to paralyze embryos at 7, 8, or 10 days of incubation and analyzed the growth of individual bones (clavicle, mandible, ulna, femur, tibia, humerus) and of individual muscles that act upon some of those bones (clavicular and sternal heads of m. pectoralis, and mm. biceps brachii, depressor mandibulae, pseudotemporalis, and adductor externus). Growth of the bones is not equally affected by paralysis. Only 27% of clavicular growth (by mass) but 77% of mandibular growth occurred in paralyzed embryos, whereas the four long bones exhibited 52-63% of their normal growth. Analysis of muscle weight, fiber length and physiological cross-sectional area (weight/fiber length) indicate that there was greater reduction of the muscles acting on the limbs than of those acting on the mandible, i.e., diminished growth of the skeleton is correlated with reduced muscular activity. Specific retardation of clavicular growth is due to fusion of sternal rudiments and collapse of the thorax, as well as virtual absence of the musculature that normally attaches to the clavicle. We discuss these results in the light of intrinsic and extrinsic factors governing growth of tne embryonic skeleton. Paralysis reduces skeletal growth by reducing both the movements taking place in ovo, and the loads imposed on the bones by muscle contraction, changes that represent alterations in the mechanical environment of the skeleton.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052060105
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  • 8
    Electronic Resource
    Electronic Resource
    Variation and timing of the cranial ossification sequence of the oriental fire-bellied toad, Bombina orientalis (Amphibia, Discoglossidae) (1984)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 182 (1984), S. 245-255 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sequence of appearance of the 17 different skull bones in the oriental fire-bellied toad, Bombina orientalis, is described. Data are based primarily on samples of ten or 11 laboratory-reared specimens of each of 11 Gosner developmental stages (36-46) representing middle through late metamorphosis. Ossification commences as early as stage 37 (hind limb with all five toes distinct), but the full complement of adult bones is not attained until stage 46 (metamorphosis complete). Number of bones present at intermediate stages is poorly correlated with external morphology. As many as four Gosner developmental stages elapse before a given bone is present in all specimens following the stage at which it may first appear. The modal ossification sequence is frontoparietal, exoccipital, parasphenoid, septomaxilla, premaxilla, vomer, nasal, maxilla, angulosplenial, dentary, squamosal, quadratojugal, pterygoid, prootic, interfrontal, sphenethmoid, and mentomeckelian. Most specimens are consistent with this sequence, despite the poor correlation between cranial ossification and external development as assayed by Gosner stage.The timing of cranial ossification in Bombina orientalis differs in many respects from that described for two other, distantly related anurans, the leopard frog (Rana pipiens) and the western toad (Bufo boreas). These include the total number and sequence of appearance of bones, and the timing of ossification relative to the development of external morphology. Interspecific variation may reflect differences in the timing of the tissue interactions known to underlie skeletal differentiation and evolution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051820302
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  • 9
    Electronic Resource
    Electronic Resource
    Development of the head skeleton of the Japanese medaka, Oryzias latipes (Teleostei) (1987)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 193 (1987), S. 135-158 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The identification, spatial relationships, and sequences of development of the cartilaginous and bony elements of the chondrocranium, osteocranium, and splanchnocranium in the medaka, Oryzias latipes, are described here for the first time. The development of the cartilaginous head skeleton commences at stage 29 and is essentially complete by stage 35 (hatching). The parasphenoid bone and two pairs of branchiostegals are present at this stage and several other replacement and dermal bones begin to appear shortly thereafter. Development of the osteocranium and ossification of the splanchnocranium continue throughout the larval and juvenile phases and are essentially complete at sexual maturity at approximately 3 months (at 25°C), at which time the fish range in length between 25 and 30 mm.The description of the adult head skeleton of O. latipes is compared to those of O. melastigma, O. luzonesis, and other Oryzias spp. previously described and a redesignation of the relationships between certain elements in the adult head skeleton is proposed, based on the developmental data presented. Furthermore, the value of the medaka as a model teleost to study the embryological origins of, and in particular, the neural crest contributions to, the cranial and visceral skeleton is outlined based on certain characteristics of the medaka's life history traits. These include the ease of obtaining embryos for which the exact time of fertilization is known (without sacrificing any brood stock) and the relatively rapid development of the chondrocranium, which is nearly complete at hatching, a process which can occur in as short a time as 6 days (at 34°C). The usefulness of the ontogenetic data obtainable from further studies into the embryonic origins of head and visceral skeletal elements revealed in the present study, is briefly discussed.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051930203
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  • 10
    Electronic Resource
    Electronic Resource
    Skull development during anuran metamorphosis: I. Early development of the first three bones to form - the exoccipital, the parasphenoid, and the frontoparietal (1988)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 195 (1988), S. 247-256 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In anuran amphibians, cranial bones typically first form at metamorphosis when they rapidly invest or replace the cartilaginous larval skull. We describe early development of the first three bones to form in the Oriental fire-bellied toad, Bombina orientalis - the parasphenoid, the frontoparietal, and the exoccipital - based on examination of serial sections. Each of these bones is fully differentiated by Gosner stage 31 (hindlimb in paddle stage) during premetamorphosis. This is at least six Gosner developmental stages before they are first visible in whole-mount preparations at the beginning of prometamorphosis. Thus, developmental events that precede and mediate the initial differentiation of these cranial osteogenic sites occur very early in metamorphosis - a period generally considered to lack significant morphological change. Subsequent development of these centers at later stages primarily reflects cell proliferation and calcified matrix deposition, possibly in response to increased circulating levels of thyroid hormone which are characteristic of later metamorphic stages. Interspecific differences in the timing of cranial ossification may reflect one or both of these phases of bone development. These results may qualify the use of whole-mount preparations for inferring the sequence and absolute timing of cranial ossification in amphibians.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051950303
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