首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
    
This article describes the growth of the anuran pectoral girdle of Rana pipiens and compares skeletal development of the shoulder to that of long bones. The pectoral girdle chondrifies as two halves, each adjacent to a developing humerus. In each, the scapula and coracoid form as single foci of condensed chondrocytes that fuse, creating a cartilaginous glenoid bridge articulating with the humerus. Based on histological sections, both the dermal clavicle and cleithrum begin to ossify at approximately the same time as the periosteum forms around the endochondral bones. The dermal and endochondral bones of the girdle form immobile joints with neighboring girdle elements; however, the cellular organization and growth pattern of the scapula and coracoid closely resemble those of a long bone. Similar to a long bone epiphysis, distal margins of both endochondral elements have zones of hyaline, stratified, and hypertrophic cartilages. As a result, fused elements of the girdle can grow without altering the glenoid articulation with the humerus. Comparisons of anuran long bone and pectoral girdle growth suggest that different bones can have similar histology and development regardless of adult morphology.  相似文献   

2.
The Hox gene complement of zebrafish, medaka, and fugu differs from that of other gnathostome vertebrates. These fishes have seven to eight Hox clusters compared to the four Hox clusters described in sarcopterygians and shark. The clusters in different teleost lineages are orthologous, implying that a "fish-specific" Hox cluster duplication has occurred in the stem lineage leading to the most recent common ancestor of zebrafish and fugu. The timing of this event, however, is unknown. To address this question, we sequenced four Hox genes from taxa representing basal actinopterygian and teleost lineages and compared them to known sequences from shark, coelacanth, zebrafish, and other teleosts. The resulting gene genealogies suggest that the fish-specific Hox cluster duplication occurred coincident with the origin of crown group teleosts. In addition, we obtained evidence for an independent Hox cluster duplication in the sturgeon lineage (Acipenseriformes). Finally, results from HoxA11 suggest that duplicated Hox genes have experienced diversifying selection immediately after the duplication event. Taken together, these results support the notion that the duplicated Hox genes of teleosts were causally relevant to adaptive evolution during the initial teleost radiation.  相似文献   

3.
    
Endocasts of the osseous labyrinth have the potential to yield information about both phylogenetic relationships and ecology. Although bony labyrinth morphology is well documented in many groups of fossil vertebrates, little is known for early Neopterygii, the major fish radiation containing living teleosts, gars and the bowfin. Here, we reconstruct endocasts of the bony labyrinth and associated structures for a sample of Mesozoic neopterygian fishes using high‐resolution computed tomography. Our sample includes taxa unambiguously assigned to either the teleost (Dorsetichthys, “Pholidophorus,” Elopoides) and holostean (“Aspidorynchus,” “Caturus,” Heterolepidotus) total‐groups, as well as examples of less certain phylogenetic position (an unnamed parasemionotid and Dapedium). Our models provide a test of anatomical interpretations for forms where bony labyrinths were reconstructed based on destructive tomography (“Caturus”) or inspection of the lateral wall of the cranial chamber (Dorsetichthys), and deliver the first detailed insights on inner ear morphology in the remaining taxa. With respect to relationships, traits apparent in the bony labyrinth and associated structures broadly support past phylogenetic hypotheses concerning taxa agreed to have reasonably secure systematic placements. Inner ear morphology supports placement of Dapedium with holosteans rather than teleosts, while preserved structure in the unnamed parasemionotid is generalized to the degree that it provides no evidence of close affinity with either of the crown neopterygian lineages. This study provides proof‐of‐concept for the systematic utility of the inner ear in neopterygians that, in combination with similar findings for earlier‐diverging actinopterygian lineages, points to the substantial potential of this anatomical system for addressing the longstanding questions in the relationships of fossil ray‐finned fishes to one another and living groups. J. Morphol. 279:426–440, 2018. © 2016 Wiley Periodicals, Inc.  相似文献   

4.
5.
    
Understanding embryonic development and ontogeny of species is a crucial part of any further biology, ecology and conservation studies. The present study describes the first detailed normal embryonic development of a tooth‐carp, Aphanius sophiae (Heckel, 1847), from fertilization to post‐ hatching. Aphanius sophiae spontaneously spawned at 24 ± 1°C. The newly laid eggs were transparent and spherical (1.45 ± 0.20 mm). We documented developmental times at 24 ± 1°C to egg activation (0.5 hr), cleavage (3 hr), blastula (10 hr), gastrula (20 hr), neurula (24 hr), somite (28 hr), turnover (60 hr), blood circulation (70 hr) and hatching (330 hr). This study contributes to a further understanding of the embryology and the early ontogeny of A. sophiae and may help improve the culture of other threatened species of the genus Aphanius.  相似文献   

6.
The developmental stages of 12 Erythrocebus patas embryos, ranging in gestational age from 30 to 50 days, is described. The pattern of embryogenesis in E. patas closely parallels the anatomic characteristics of human and other nonhuman primate embryos between stages 12 and 23. However, there is a delay in development in E. patas similar to that observed in human embryos which differs from the macaques and baboons. This temporal difference in the embryonic period is an important factor in the design and analysis of early pregnancy studies in this species.  相似文献   

7.
8.
    
The development of Callorhinchus milii, a primitive chondrichthyan fish (Subclass Holocephali) is described in detail based on a complete series of embryos from stage 17 to hatching. The external features of these specimens, in comparison with other chondrichthyan embryos, are used to establish the first staging table for any chimaeroid species. Each stage of C. milii is defined by a suite of morphological characters in addition to total length, including the number of somites, extent of external pigmentation, eye size and shape, head flexure, heart morphology, and size and shape of paired and unpaired fins. Particular attention is given to features of the gill arches and associated structures, including external gill filaments and the opercular flap. Embryos of this species also possess a transient rostral bulb, a feature unique to chimaeroids. Embryological development of Callorhinchus milii is similar to that previously described for sharks and batoids (Subclass Elasmobranchii), including the spiny dogfish, Squalus acanthias, the Japanese bullshark, Heterodontus japonicus, the lesser spotted dogfish, Scyliorhinus canicula, the frill shark, Chlamydoselachus anguineus, the guitarfish, Rhinobatus halavi, and the skate, Raja brachyura. Callorhinchus milii is also similar in overall development to another holocephalan, Hydrolagus colliei. A review of previous staging schemes confirms that early morphological development in all three major chondrichthyan lineages (sharks, batoids, and chimaeras) can be correlated using a common set of stages. A uniform staging system is provided that should prove useful in continuing ontogenetic and phylogenetic studies of this entire clade of fishes. J. Morphol. 236:25–47, 1998. © 1998 Wiley-Liss, Inc.  相似文献   

9.
  相似文献   

10.
    
Major advances have been made in the last 10 years in the genetics of skeletogenesis. This has followed the general progress in our understanding of the genetic control of development in chicken and mouse and more recent advances in human genetics. This large field now encompasses three smaller but distinct fields of investigation. Those are skeleton patterning, cell differentiation in the skeleton, and cell function in the skeleton. This review focuses primarily on advances in understanding cell differentiation and cell function in the skeleton at the genetic level. Dev. Genet. 22:301–313, 1998. © 1998 Wiley-Liss, Inc.  相似文献   

11.
    
The presence of a synsacrum formed by the fusion of vertebrae that come into closed contact with the ilium and ischium is a feature that characterizes the clade Xenarthra. Nevertheless, the proper identity of each vertebral element that forms it is a matter of discussion. In this article, we provide ontogenetic information about skeletal ossification of the xenarthran synsacrum and define the position of the sacrocaudal limit within it. We analyzed the synsacrum of 25 specimens of nonadult and 101 adult armadillos and anteaters: Dasypus hybridus, D. novemcinctus, Chaetophractus vellerosus, C. villosus, Tamandua tetradactyla, and Myrmecophaga tridactyla. Two sets of vertebrae were identified: an anterior set, often attached to the iliac bones, in which transverse processes are originated mainly from an expansion of the base of the neural arches, and secondarily from a lateroventral ossification center. A posterior set is characterized by a series of vertebrae along which extra lateral ossifications (described here for the first time) are developed and form exclusively the transverse processes. Among armadillos, the sacrocaudal limit is set between the last vertebrae attached to the iliac bones and the first vertebrae that form the dorsal border of the sacroischial fenestra. In addition, anterior free caudals also showed extra lateral ossifications forming exclusively the transverse processes, supporting the notion that more posterior synsacrals are in fact caudal vertebrae that were incorporated to the synsacrum. In pilosans, the sacrocaudal limit is set between the first vertebrae that come into contact with the ischial bones and the immediately anterior one. However, the pattern of homologies is obscured by the low resolution in the ontogenetic sequence when compared to that of armadillos. J. Morphol. 276:494–502, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   

12.
    
The persistence of the notochord into the skeletally mature life stage is characteristic of gekkotans, but is otherwise of rare occurrence among amniotes. The taxonomic diversity of Gekkota affords the opportunity to investigate the structure and development of this phylogenetically ancestral component of the skeleton, and to determine its basic characteristics. The gekkotan notochord spans almost the entire postcranial long axis and is characterized by a moniliform morphology with regularly alternating zones of chordoid and chondroid tissue. Chordoid tissue persists in the region of intervertebral articulations and occupies the cavitations that lie between the centra of the amphicoelous vertebrae. Chondroid tissue is restricted to zones in which the diameter of the notochord is reduced, corresponding to mid‐vertebral locations. In the tail, these zones of chondroid tissue are associated with the autotomic fracture planes. Chondroid tissue first manifests during late embryogenesis, appears to differentiate from pre‐existing chordoid tissue, and has the histological and histochemical characteristics of cartilage. Our observations lend support to the hypothesis that cartilage can be derived directly from notochordal tissue, and suggest that the latter may be an evolutionary and developmental precursor to chordate cartilage. The persistence of chordoid tissue in the intervertebral regions of amphicoelous vertebrae is consistent with a suite of paedomorphic traits exhibited by gekkotans and suggests that the typical hydrostatic nature of notochordal tissue may play a role in mechanically governing patterns of displacement between adjacent amphicoelous vertebrae that lack extensive centrum‐to‐centrum contact. Morphol., 2012. © 2012 Wiley Periodicals, Inc.  相似文献   

13.
14.
    
The production of cartilage (chondrogenic patterning) in the limb is one of the best‐studied examples of the emergence of form in developmental biology. At the core of the theoretical study is an effort to understand the mechanism that establishes the characteristic distribution of cartilage in the embryonic limb, which defines the future sites and shapes of bones that will be present in the mature limb. This review article gives an overview of the history and current state of a rich literature of mathematical and computational models that seek to contribute to this problem. We describe models for the mechanisms of limb growth and shaping via interaction with various chemical fields, as well as models addressing the intrinsic self‐organization capabilities of the embryonic mesenchymal tissue, such as reaction‐diffusion and mechanochemical models. We discuss the contributions of these models to the current understanding of chondrogenesis in vertebrate limbs, as well as their relation to the varied conceptual models that have been proposed by experimentalists. Birth Defects Research (Part C) 96:176–192, 2012. © 2012 Wiley Periodicals, Inc.  相似文献   

15.
16.
17.
    
The CCN family of genes constitutes six members of small secreted cysteine rich proteins, which exists only in vertebrates. The major members of CCN are CCN1 (Cyr61), CCN2 (CTGF), and CCN3 (Nov). CCN4, CCN5, and CCN6 were formerly reported to be in the Wisp family, but they are now integrated into CCN due to the resemblance of their four principal modules: insulin like growth factor binding protein, von Willebrand factor type C, thrombospondin type 1, and carboxy‐terminal domain. CCNs show a wide and highly variable expression pattern in adult and in embryonic tissues, but most studies have focused on their principal role in osteo/chondrogenesis and vasculo/angiogenesis from the aspect of migration, growth, and differentiation of mesenchymal cells. CCN proteins simultaneously integrate and modulate the signals of integrins, bone morphogenetic protein, vascular endothelial growth factor, Wnt, and Notch by direct binding. However, the priority in the use of the signals is different depending on the cell status. Even the equivalent counterparts show a difference in signal usage among species. It may be that the evolution of the CCN family continues to keep pace with vertebrate evolution itself.  相似文献   

18.
  总被引:2,自引:2,他引:0  
The authors investigated the presence of various carotenoids in the fish of certain species in the Rajidae (Raja georgiana), Muraenolepidae (Muraenolepis microps), Notothenidae rDissostichus eleginoides, Notothenia gibberifrons, Notothenid rossi-marmorata, Trematomus hansoni) and Chaenichthyidae (Chaenocephalus aceratus, Champsocephalus gunnari, Pseudochaenichthys georgianus) family from the Antarctic by means of columnar and thin-layer chromatography.The following carotenoids were identified: ß-carotene, -cryptoxanthin, canthaxanthin, flavoxanthin, isozeaxanthin, zeaxanthin, tunaxanthin, lutein-5, 6-epoxide, aurochrome, aurochrome-like, auroxanthin, astaxanthin, astaxanthin ester and 4-hydroxy--carotene.The total carotenoid content of this fishes was from 0.066 to 0.122 µg/g fresh weight.  相似文献   

19.
  总被引:1,自引:0,他引:1  
Axial patterning in embryonic skeletogenesis associates with coordinated programming of somitogenesis and angiogenesis. As seen in endochondral bone formation, skeletogenesis is closely related to angiogenesis during development. PlexinD1 is a member of plexin family, is expressed in central nervous system and endothelium, and plays a role in blood vessel patterning and endothelium positioning during embryonic development. Here, we examined the effects of PlexinD1 deficiency on skeletogenesis. Three-dimensional micro CT examination revealed that PlexinD1 deficiency resulted in axial skeletal patterning defects including malformation in vertebral body and rib bone shape. Histological examination of the vertebral bodies and long bones showed that PlexinD1 deficiency altered the development of cartilage. PlexinD1 deficiency did not affect the levels of von Willebrand factor staining in relatively large vessels not attached but close to the vertebral body of mice. However, PlexinD1 deficiency reduced the von Willebrand factor (vWf) staining in most of the microvasculatures attached to the vertebral bone. PlexinD1 was expressed in osteoblastic cells and bone tissues of newborn and adult mice. As most of the homozygous knockout mice did not survive, we examined the role of PlexinD1 in bone formation in heterozygous adult mice subjected to bone marrow ablation. However, PlexinD1 heterozygous knockout did not reveal defects in new bone formation. In conclusion, PlexinD1 is involved in the patterning of axial skeletogenesis.  相似文献   

20.
Periosteum-derived progenitor cells (PDPCs) were isolated by characteristic surface markers. Reproducibility of immunophenotypes of the PDPCs was characterized by flow cytometric analysis using fluorescence-activated cell sorter (FACS). SH2+, SH3+, SH4+, CD9+, CD90+ and CD105+ were important eternal characteristic cell surface markers for the PDPCs. The characterized PDPCs maintained their chondrogenic potential in pellet cultures until the 15th passage from primary cell culture.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号