771 resultados para skull ontogeny
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The coordinate growth of the brain and skull is achieved through a series of interactions between the developing brain, the growing bones of the skull, and the fibrous joints, or sutures, that unite the bones. These interactions couple the expansion of the brain to the growth of the bony plates at the sutures. Craniosynostosis, the premature fusion of the bones of the skull, is a common birth defect (1 in 3000 live births) that disrupts coordinate growth and often results in profoundly abnormal skull shape. Individuals affected with Boston-type craniosynostosis, an autosomal dominant disorder, bear a mutated copy of MSX2, a homeobox gene thought to function in tissue interactions. Here we show that expression of the mouse counterpart of this mutant gene in the developing skulls of transgenic mice causes craniosynostosis and ectopic cranial bone. These mice provide a transgenic model of craniosynostosis as well as a point of entry into the molecular mechanisms that coordinate the growth of the brain and skull.
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n.s. no.39(1998)
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v.33:no.9(1975)
Native People of the American Northwest: Population History from the Perspective of Skull Morphology
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Wormian bones (WB) are irregular small cranial ossicles found along suture lines and fontanels. In Brazil, gunshot wounds to the skull are quite common in young individuals. Nevertheless, as far as we know, this is the first report of a WB giving an erroneous aspect of gunshot entrance due to its displacement position. The present manuscript describes the case of a Brazilian young man who died due to ballistic trauma, where a gaping bony defect on the right side of the skull was thought to be the exit wound of an injury related to the destruction found on the left side, highly suggestive of firearm injury. Thus, this case study has brought to light similarities between a traumatic lesion and an orifice of a WB, with emphasis on differential diagnosis during routine anthropological examinations.
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Development plays an important part in shaping adult morphology and morphological disparity, yet its influence on evolutionary processes is seldom explored because of a lack of preservation of ontogenetic stages in the fossil record. By preserving their entire ontogenetic history within their test, and with the advent of high-resolution imaging techniques, planktic foraminifera allow us to investigate the influence of developmental constraints on disparity. Using Synchrotron radiation X-ray tomographic microscopy (SRXTM), we reconstruct the ontogenetic progression of seven species across several of the major morphotypic groups of planktic foraminifera, including morphotypes of a species exhibiting high phenotypic plasticity and closely related pseudo-cryptic sister-taxa. We show differences in growth patterns between the globigerinid species, which appear more tightly regulated within the framework of isometry from the neanic stage, and the globorotaliid species, whose adult stages present allometric trends. Morphological change through ontogeny results in a change in surface area to volume ratios. Different metabolic processes therefore dominate at different stages of ontogeny, changing the vulnerability of the organism to environmental influences over growth, from factors affecting diffusion rates in the juvenile to those affecting energy supply in the adult. These findings identify some of the parameters within which evolutionary mechanisms have to act.
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Mode of access: Internet.
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Mode of access: Internet.
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"April, 1955."
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"Remarks and references to literature": vol. 2, p. [459]-490.
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From the Philosophical transactions of the Royal society, 1866, 1869, 1871, 1873, 1874, 1876, 1878, 1881 and 1882.
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Carbon dust on Ross Stipple Board with water color added
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Bound in green publisher's cloth with gilt-stamped spine, blind-stamped boards, and yellow coated endpapers.
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"From the Smithsonian report for 1957."