Abstract:
:Substantial changes in bone histology accompany the secondary adaptation to life in the water. This transition is well documented in several lineages of mammals and non-avian reptiles, but has received relatively little attention in birds. This study presents new observations on the long bone microstructure of penguins, based on histological sections from two extant taxa (Spheniscus and Aptenodytes) and eight fossil specimens belonging to stem lineages (†Palaeospheniscus and several indeterminate Eocene taxa). High bone density in penguins results from compaction of the internal cortical tissues, and thus penguin bones are best considered osteosclerotic rather than pachyostotic. Although the oldest specimens sampled in this study represent stages of penguin evolution that occurred at least 25 million years after the loss of flight, major differences in humeral structure were observed between these Eocene stem taxa and extant taxa. This indicates that the modification of flipper bone microstructure continued long after the initial loss of flight in penguins. It is proposed that two key transitions occurred during the shift from the typical hollow avian humerus to the dense osteosclerotic humerus in penguins. First, a reduction of the medullary cavity occurred due to a decrease in the amount of perimedullary osteoclastic activity. Second, a more solid cortex was achieved by compaction. In extant penguins and †Palaeospheniscus, most of the inner cortex is formed by rapid osteogenesis, resulting an initial latticework of woven-fibered bone. Subsequently, open spaces are filled by slower, centripetal deposition of parallel-fibered bone. Eocene stem penguins formed the initial latticework, but the subsequent round of compaction was less complete, and thus open spaces remained in the adult bone. In contrast to the humerus, hindlimb bones from Eocene stem penguins had smaller medullary cavities and thus higher compactness values compared with extant taxa. Although cortical lines of arrested growth have been observed in extant penguins, none was observed in any of the current sampled specimens. Therefore, it is likely that even these 'giant' penguin taxa completed their growth cycle without a major pause in bone deposition, implying that they did not undergo a prolonged fasting interval before reaching adult size.
journal_name
J Anatjournal_title
Journal of anatomyauthors
Ksepka DT,Werning S,Sclafani M,Boles ZMdoi
10.1111/joa.12367subject
Has Abstractpub_date
2015-11-01 00:00:00pages
611-30issue
5eissn
0021-8782issn
1469-7580journal_volume
227pub_type
杂志文章abstract::Ethmoturbinates, nasoturbinates, and maxilloturbinates are well developed in the narial tract of land-dwelling artiodactyls ancestral to whales, but these are greatly reduced or lost entirely in modern whales. Aegyptocetus tarfa is a semiaquatic protocetid from the middle Eocene of Egypt. Computed axial tomography sca...
journal_title:Journal of anatomy
pub_type: 杂志文章
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更新日期:2020-01-01 00:00:00
abstract::The differentiation and patterning of tendon fibroblasts is at present a poorly understood aspect of musculoskeletal development in the vertebrate limb. Precursors of tendon fibroblasts originate in the somatic mesoderm adjacent to the early limb bud and gradually become incorporated into the limb mesenchyme as develo...
journal_title:Journal of anatomy
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更新日期:2003-01-01 00:00:00
abstract::Lacking fur, living in eusocial colonies and having the longest lifespan of any rodent, makes naked mole-rats (NMRs) rather peculiar mammals. Although they exhibit a high degree of polymorphism, skeletal plasticity and are considered a novel model to assess the effects of delayed puberty on the skeletal system, scarce...
journal_title:Journal of anatomy
pub_type: 杂志文章
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1990-10-01 00:00:00
abstract::The bioavailability of polystyrene particles (1 microns) labelled with FITC (3M Company, Düsseldorf) was tested in rats after enteral administration. Since macromolecules and particles are preferentially transported in the lymph, the number of particles was counted in the lymph of the thoracic duct over a 6 h period. ...
journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1982-08-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
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更新日期:2015-03-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1986-10-01 00:00:00
abstract::Developing Xenopus embryos treated during gastrulation with 22 micrograms/l of salmar calcitonin in the ambient water develop into larvae exhibiting a decrease in interocular distance. In view of the hypocalcaemic properties of calcitonin and the importance of calcium ions in cell aggregation, this phenomenon has been...
journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1985-01-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1990-06-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章,评审
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更新日期:2005-12-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1981-01-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1982-08-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:10.1046/j.1469-7580.2003.00184.x
更新日期:2003-06-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:10.1111/j.1469-7580.2008.00960.x
更新日期:2008-10-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 历史文章,杂志文章
doi:10.1111/j.1469-7580.2007.00711.x
更新日期:2007-04-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章,评审
doi:10.1111/joa.12063
更新日期:2014-01-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:10.1111/joa.12815
更新日期:2018-07-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1984-01-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1995-04-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1978-03-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:10.1111/j.0021-8782.2004.00304.x
更新日期:2004-06-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1996-02-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:10.1046/j.1469-7580.2000.19620293.x
更新日期:2000-02-01 00:00:00
abstract::In the spinotrapezius muscle of the rat and the mouse approximately equal proportions of A,B and C fibres are present. The spinotrapezius therefore contains a lower proportion of B fibres than are known to be present in soleus, but a higher proportion than in tibialis anterior. These results are consistent with the fu...
journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1977-02-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1985-05-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
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更新日期:2016-03-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:
更新日期:1975-11-01 00:00:00
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journal_title:Journal of anatomy
pub_type: 杂志文章
doi:10.1111/joa.12506
更新日期:2016-11-01 00:00:00
abstract::The glycan composition of the N- and O-linked oligosaccharides of the follicle (Sertoli) cells of the urodele amphibian Pleurodeles waltl testis were identified by lectin histochemistry, performed alone or in combination with enzymatic and chemical deglycosylation methods. The follicle cells were shown to contain: (1)...
journal_title:Journal of anatomy
pub_type: 杂志文章
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更新日期:2001-06-01 00:00:00