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  • 1
    Electronic Resource
    Electronic Resource
    Fine structure of the developing frontal bones and scales of the cranial vault in the cichlid fish Hemichromis bimaculatus (Teleostei, Perciformes) (1993)
    Springer
    Cell & tissue research 273 (1993), S. 511-524 
    Details
    ISSN: 1432-0878
    Keywords: Bone ; Scales ; Development ; Hemichromis bimaculatus (Teleostei, Perciformes)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The development of the frontal bone and the formation of the first head scales are described during post-embryonic ontogeny of Hemichromis bimaculatus, using light and transmission electron microscopy. The frontal bone originates close to the cartilaginous taenia marginalis in a loose mesenchymal cell condensation (=primordium) lying 1 μm from the epidermis with which it establishes no cell contacts. The anlage appears at 4.2 mm standard length (SL) in the form of the membranodermal component of the bone, and extends first over the brain and then over the eye; the neurodermal component forms later to surround the supraorbital canal. The first head scales appear at 10.0 mm SL in a dense cell condensation (papilla) adjoining the epidermal-dermal junction and, once formed, remain in this position. In both organs, the initial matrix is similarly composed of “woven-fibred” bone that soon mineralizes in a similar manner to other dermal elements. In some areas of the frontal bone, “parallel-fibred” bone is deposited unequally on both surfaces, whereas isopedine is deposited in scales on the deep surface only. Osteoblastic features confirm this eccentric growth. Differences in the shape, organization and localization of the mesenchymal condensations giving rise to the frontal bone and to the scale reflect the existence of two types of dermal cell condensations. Our data are compared with those available for the post-cranial dermal skeleton of fishes both from a developmental and structural viewpoint. Structural differences in the matrices of the frontal bone and scales are discussed in a phylogenetic perspective.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333705
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  • 2
    Electronic Resource
    Electronic Resource
    Development of cartilage and bone tissues of the anterior part of the mandible in cichlid fish: A light and TEM study (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 233 (1992), S. 357-375 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The present paper presents ultrastructural details of chondrogenesis of Meckel's cartilage and of ossification of its associated peri- and parachondral bones in a teleost fish, the cichlid Hemichromis bimaculatus. We have distinguished four stages during chondrogenesis, each of which is characterized by specific cellular and matrix features: blastema, primordium, differentiated cartilage and cartilage surrounded by perichondral bone. The blastema is characterized by prechondroblasts and the lack of cartilage matrix; the primordium by chondroblasts and the onset of secretion of matrix of fibrillar and granular nature; differentiated cartilage is characterized by chondrocytes and larger amounts of typical hyaline cartilage matrix. Once perichondral bone is laid down, the chondrocytes show degenerative features but not true hypertrophy. Differentiation of the cartilage cells is attended with cytoplasmic changes indicative of an increasing secretory activity. There is a regional calcification of the cartilage matrix by fusion of calcospherites. Chondrogenesis of the symphyseal area is continuous with that of the rami but starts slightly later. Formation of perichondral bone at the cartilage surface is attended with the deposition of a transitional zone apparently containing a mixture of the two matrices. The role of the perichondral cells is discussed and it is proposed that they may contribute to the formation of the two matrices. The transitional zone may then result either from a diffusion process or from the simultaneous deposition of elements of the two matrices. Growth of the cartilage is argued to be largely the result of matrix secretion, except in the symphyseal area where appositional growth probably occurs until the region is completely covered by perichondral bone. This paper provides a basis for further studies on the developmental interactions between cartilage, bone and teeth during mandibular development in cichlids. © 1992 Wiley-Liss, Inc.
    Additional Material: 44 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092330304
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  • 3
    Electronic Resource
    Electronic Resource
    Bone and cartilage resorption in relation to tooth development in the anterior part of the mandible in cichlid fish: A light and TEM study (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 234 (1992), S. 1-14 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This paper presents ultrastructural features of the contact region between particular tooth germs and Meckel's cartilage prior to, during, and after initial resorption of the perichondral bone and of the cartilage in the cichlids Hemichromis bimaculatus and Astatotilapia burtoni. Imminent resorption opposite such teeth is announced by the presence, in this region, of a particular cell type, considered to be a stage in the cytodifferentiation of osteoclasts. Slightly later, an osteoclast with typical ruffled border is seen to open a fenestra in the perichondral bone which surrounds Meckel's cartilage. Although the action of the osteoclast is directed primarily towards the bone, it may also affect, to a much lesser extent, the underlying uncalcified cartilage. Typically, fibroblast-like cells invade the resorption cavity along with the osteoclast; the tooth germ soon follows. Capillaries are seen to invade the cartilage only at a later stage when a large cavity has been established. It is proposed that the fibroblast-like cells may have a dual function: degradation of cartilage and deposition of new bone. Although these processes are normally limited to the area surrounding tooth germs at specific loci, tooth germs in other positions may sometimes be seen to invade the cartilage. They do so either passively, because of the existence of such a cavity, or as a result of their own resorption-inducing activity. Whatever the mechanism, attachment bone is being deposited within the erosion cavity and on the surface of the exposed perichondral bone. The stimuli possibly eliciting resorption of Meckel's cartilage are discussed. It is hypothesized that pressure exerted by the growing tooth germ may stimulate the osteoblasts covering the bone surface and, in this way, provoke osteoclastic bone resorption. © 1992 Wiley-Liss, Inc.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092340102
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  • 4
    Electronic Resource
    Electronic Resource
    Light and TEM study of nonregenerated and experimentally regenerated scales of Lepisosteus oculatus (holostei) with particular attention to ganoine formation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 240 (1994), S. 189-207 
    Details
    ISSN: 0003-276X
    Keywords: Lepisosteus oculatus ; Scales ; Scale regeneration ; Ganoine formation ; Transmission electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: The structure of nonregenerated and experimentally regenerated scales of the holostean fish Lepisosteus oculatus and the events taking place before and during ganoine depostition on the scale surface were studied. The aim of this study was to answer the question of the origin of the ganoine in lepisosteids, the scales of which are devoid of dentine, and to compare them to ganoine formation in polypterid scales and to enamel formation in teeth.Methods: Two adult specimens were used and the scale structure was studied using light and transmission electron microscopy. Regeneration was used as an alternative to the lack of developmental stages and to induce ganoine deposition on the scale surface.Results: Nonregenerated scales are composed of a thick, avascular bony plate capped by ganoine that is covered either by the epidermis or by dermal elements. The ganoine surface is separated from the covering soft tissues by an unmineralized layer, the ganoine membrane. During the first 2 months of regeneration, the bony plate forms. It differs from the bony plate of nonregenerated scales only by its large, woven-fibered central region and by the presence of numerous vascular canals. Shortly before ganoine deposition, the osteoblasts cease their activity and an epithelial sheet comes to contact them and spreads on the bony surface. This epithelial sheet is connected to the epidermis by a short epithelial bridge only and is composed of two layers: the inner ganoine epithelium (IGE), in contact with the bone surface and composed of juxtaposed columnar cells that synthesize the ganoine matrix, preganoine; the outer ganoine epithelium (OGE), composed of elongated cells, the surface of which is separted from the overlying dermal space by a basal lamina. Isolated patches of preganoine are deposited by the IGE cells in the upper part of the osteoid matrix of the scale. The interpenetrated preganoine and osteoid matrices constitute an anchorage zone, between ganoine and bone. Preganoine patches fuse and a continuous layer of preganoine is progressively synthesized by the IGE cells. Preganoine progressively mineralizes to become ganoine.Conclusions: The processes of ganoine formation are similar to those known for the ganoine in the polypterid scales and to those described for enamel deposition in teeth. Ganoine is enamel. © 1994 Wiley-Liss, Inc.
    Additional Material: 50 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092400206
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  • 5
    Electronic Resource
    Electronic Resource
    Fine structure of regenerating scales and their associated cells in the cichlid Hemichromis bimaculatus (Gill) (1984)
    Springer
    Cell & tissue research 237 (1984), S. 537-547 
    Details
    ISSN: 1432-0878
    Keywords: Scale ; Regeneration ; Ultrastructure ; Cichlid ; Hemichromis bimaculatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Scale regeneration has been studied in Hemichromis bimaculatus. The removed scale, which serves as a control, is covered by its surrounding scleroblasts as can be seen with scanning electron microscopy. Subsequently, during regeneration, a population of scleroblasts arises in the empty dermal pocket as shown with transmission electron microscopy. At first, an elongated papilla of regeneration forms, probably from the differentiation of dermal fibroblasts. A scale anlage composed of the osseous layer appears in the middle of the papilla, which becomes a regenerating bag. All the surrounding large scleroblasts are involved in scale formation, although later three populations of scleroblasts specialize according to their location around the scale. Superficial scleroblasts flatten when the final thickness of the osseous layer of the scale is attained; the deep scleroblasts are responsible for the formation of the basal plate whereas marginal scleroblasts increase the diameter of the osseous layer of the scale. During scale regeneration, scleroblasts are more numerous and larger than during scale ontogenesis. In particular, deep scleroblasts form a columnar epithelium when the basal plate is laid down, a feature which is not found during scale ontogenesis. Moreover, the regenerated basal plate exhibits an orthogonal “plywood” arrangement that is never seen in the embryonic scale where the “plywood” is of the intermediate type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228438
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  • 6
    Electronic Resource
    Electronic Resource
    Evidence that mineralized spherules are involved in the formation of the superficial layer of the elasmoid scale in cichlids Cichlasoma octofasciatum and Hemichromis bimaculatus (Pisces, Teleostei): an epidermal active participation? (1988)
    Springer
    Cell & tissue research 253 (1988), S. 165-172 
    Details
    ISSN: 1432-0878
    Keywords: Scale formation ; Mineralization ; Epidermis ; Cichlasoma octofasciatum, (Teleostei) ; Hemichromis bimaculatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The region between the epidermis and the surface of the overlapping part of scales has been studied in two cichlid teleosts using transmission electron microscopy. In a few specimens only, numerous mineralized spherules (∼1 μm in diameter) are observed in the loose dermis and at the scale surface, and form a large part of the superficial outer limiting layer of the scale. In the loose dermis (stratum laxum) and close to the scale surface spherules are either free or included in dermal cells. When free, they are dispersed in the extracellular matrix of the dermis, among the fibrils of anchoring bundles, and fused with the scale surface. When included in cell vacuoles, they lie close to the lamina densa and to the scale surface. Steps in the formation of the mineralized spherules are only seen in the lamina densa of the basement membrane. The spherules contain needle-like mineral crystals radially orientated and an organic matrix of stippled material and dense granules, some of which form concentric lines around the centre of the spherules. The results suggest that mineralized spherules form in the lamina densa and pass through the dermis to the scale surface in which they are incorporated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221751
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  • 7
    Electronic Resource
    Electronic Resource
    Osteoclasts in teleost fish: Light-and electron-microscopical observations (1990)
    Springer
    Cell & tissue research 260 (1990), S. 85-94 
    Details
    ISSN: 1432-0878
    Keywords: Osteoclasts ; Bone resorption ; Salmo fario, Myleus rhomboidalis, Eigenmannia virescens, Astatotilapia elegans, Astatotilapia burtoni, Hemichromis bimaculatus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This paper reports the common occurrence of osteoclasts during normal and experimental bone resorption in a number of teleost fishes. Light-microscopical observations on osteoclasts are presented in resorption areas on perichondral bone (mandibula and pharyngeal jaws of cichlids and vertebrae of gymnotids), on dermal bone (mandibula of salmonids and characoids and frontal bone of cichlids), on chondroid bone (pharyngeal jaws of cichlids), and on elasmoid body scales (eichlids and gymnotids). Osteoclasts acting along the bone surface usually lie in a Howship's lacuna whereas others are wrapped around bone extremities. Electronmicroscopical observations reveal that teleost osteoclasts show features similar to those of higher vertebrate osteoclasts, c.g., the presence of a ruffled border and the occurrence of numerous vacuoles, lysosomes and mitochondria. The multinucleated aspect that characterizes osteoclasts in other vertebrate groups is not a distinct feature of teleost osteoclasts since some are possibly mononucleated. Teleost osteoclasts are also able to resorb uncalcified tissues adjoining bone resorption areas, either as a primary process directed toward the tissue (basal plate of elasmoid scale) or as a secondary phenomenon (cartilage).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297493
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  • 8
    Electronic Resource
    Electronic Resource
    Development and fine structure of the bony scutes in Corydoras arcuatus (Siluriformes, callichthyidae) (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 215 (1993), S. 225-244 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development and the structure of the bony scutes have been studied in a growth series of the armored catfish Corydoras arcuatus using light and electron microscopy. Fibroblast-like cell condensations appear in the dermis, in the posterior region of the caudal peduncle, and these will constitute the scute papillae. Collagen bundles of the preexisting dermis colonized by the papilla cells are remodeled and incorporated in the papilla to form, in addition to newly synthesized woven-fibered bony material, the initium of the scute. This process of formation differs from that described for the dermal papilla of an elasmoid scale. During growth, the osteoblasts surrounding the scute constitute the scute sac in which the scute grows. Parallel-fibered bone is deposited on both sides of the initium, and osteoblasts are incorporated within the scute matrix. The remodeling and incorporation of collagen bundles of the preexisting dermis is maintained during growth only in the deep, anterior region of the scute. The posterior region and the upper surface of the scute are close to the epidermal-dermal boundary. When growth slows down in the upper part of the scute, a characteristic, well-mineralized tissue, composed of thin vertical fibrils and granules and devoid of typical striated collagen fibrils, is deposited on the scute surface. A new term, hyaloine, is introduced for this nonosseous, highly mineralized layer constituting the upper part of the scute. Hyaloine shows thin electron-dense lines, which probably correspond to periodic growth arrests. The structure and localization of the hyaloine are compared to other well-mineralized, similar tissues found on the surface of the dermal skeleton in lower vertebrates. © 1993 Wiley-Liss, Inc.
    Additional Material: 35 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052150305
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  • 9
    Electronic Resource
    Electronic Resource
    Scales in young Polypterus senegalus are elasmoid: New phylogenetic implications (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 186 (1989), S. 315-323 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A component of the basal plate which has a plywood-like organization similar to that of the elasmoid scales of teleosts is described in the scales of Polypterus senegalus for the first time. The origin and development of this structure is studied in young (50-117 mm, standard length) and adult (225 and 240 mm) specimens using light and electron microscopy. In 50 mm fish, the scales are imbricated and composed mainly of a succession of orthogonal collagen layers forming a plywood-like structure, the isopedin. The outer surface of the scale is ornamented locally by irregular patches of collagenous material. The layers are not mineralized, whereas the superficial patches are well calcified. The isopedin thickens until it has 12-15 layers and then stops growing (88 mm fish). It mineralizes irregularly from its upper part, and two vascular regions, surrounded by woven-fibered osseous material, form on the outer and deeper surfaces of the isopedin. These regions thicken while the vascular canals close by centripetal deposition of parallel-fibered osseous tissue. The outer region is the superficial part of the mature scale (called here osteodentin), which is covered by the ganoine deposited by the epidermal cells. The deeper part constitutes the definitive basal plate, composed of parallel-fibered osseous tissue. The results show (1) that the young ganoid scales of Polypterus senegalus have a structure similar to that of typical elasmoid scales; and (2) that the isopedin structure does not change during ontogeny and so represents a permanent record of the first ontogenetic stages. The phylogenetic implication of these results is that the elasmoid scales of teleosts arose by a process of paedomorphosis.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001860308
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