Biography Hams Histology Pdf


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Arthur W Ham; David H Cormack. Ham, Arthur W. (Arthur Worth), Add tags for "Ham's histology". PDF | On Oct 10, , Alaa Sayed Abou-Elhamd and others published Histology . Download full-text PDF Cormack, D. H. (): Ham´s Histology. Ham's histology by Arthur W. Ham, , Lippincott edition, in English - 9th ed.

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Canadian Journal of Zoology

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Primary Entity http: Book , schema: CreativeWork , schema: Intangible ;. Cormack " ;. InformationResource , genont: Home About Help Search. All rights reserved. Although some direct observations of the dodo are available from the 16th and 17th century, these are by sailors with no scientific background and are mainly contradictory and imprecise 8.

A number of contemporary illustrations of the dodo are known, but most are considered unreliable 8. Recent body mass estimates range from 9.

Our research is therefore highly significant in that using bone microstructure we provide novel insight into the reproductive behavior, growth strategy, and molting habits of this recently extinct enigmatic bird Ontogenetic trajectory The histology of the dodo is similar to that of modern birds, which generally have three distinct layers that make up the bone wall 12 , The central layer typically consists of fibrolamellar bone, which is a rapidly-deposited woven tissue, rich in primary osteons.

This is overlain by a poorly vascularized or avascular tissue termed an outer circumferential layer OCL , and underlain by an inner circumferential layer ICL , which is composed of more slowly deposited lamellar bone tissue terminology sensu Chinsamy-Turan 13 ; Fig.

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Figure 1 Transverse thin sections of hindlimb bones of the dodo showing different stages of the ontogenetic growth series. Full size image Our sample of dodo bones shows different stages of growth and maturity.

Tibiotarsus ddtbt14 , has a cortex largely comprising of fibrolamellar bone tissue consisting of woven bone with many primary osteons, which suggests a rapid rate of bone deposition.

Remnants of the periosteum along the outer surface are preserved and an inner circumferential layer ICL , without resorption traces, is well developed Fig.

These characteristics indicate a late juvenile stage that has passed the most rapid phase of growth, but one that has not yet reached adulthood 13 , 14 , making it the youngest specimen in our sample; all the other specimens studied appear to be adults, at slightly different stages of maturity.

Several specimens appear to be young adults in their first year post sexual maturity ddfem02, ddfem03, ddfem04, ddfem05, ddhu01, ddtbt The rest of the sample ddfem01, ddtbt01, ddtbt02, ddtbt03, ddtbt05, ddtbt06, ddtbt08, ddtbt09, ddtbt10, ddtbt13 represent more mature adults. Figure 2 Transverse thin sections of hindlimb bones of the dodo showing medullary bone.

Full size image Figure 3 Transverse thin sections of a humerus of the dodo.

Full size image Figure 4 Transverse sections of hindlimb bones of the dodo showing resorption cavities which are interpreted as evidence of molt. Full size image Figure 5 Transverse sections of hindlimb bones of the dodo showing resorption cavities which are interpreted as evidence of molt. The endosteal margin is clearly resorptive, and several resorption cavities are evident. Full size image Only the tarsometatarsi ddtmt01 and ddtmt02 show a large amount of secondary reconstruction, which obscures the triple-layer structure of the bone wall.

This could be linked to biomechanical adaptations 13 , or possibly suggests the importance of these bones as calcium reservoirs Identification of females For two of the specimens, one tibiotarsus ddtbt08 and one femur ddfem04 , a distinctive woven bone tissue medullary bone 13 , extends centripetally from the ICL into the medullary cavity Fig.

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This bone tissue develops in ovulating birds and is utilized in the formation of the calcium rich eggshells 3 , The tibiotarsus ddtbt08 has a large amount of medullary bone, making up about 4. Osteohistological indicator of molting Most adult specimens have many secondary osteons or resorption cavities in the compacta.

The resorption cavities have an area of between 0. In some of these enlarged cavities, a centripetal deposition of lamellar bone occurs Fig. Discussion The youngest individuals in our sample appear to be late stage juveniles. A large proportion of their compacta comprises fibrolamellar bone, which suggests that during early ontogeny bone deposition occurred at a rapid rate 13 , Such rapid rates of growth during the early growth stages is typical for modern birds; it has also been described in other species such as the secretary bird Sagittarius serpentarius 14 , Japanese quail Coturnix japonica 22 , king penguin Aptenodytes patagonicus 23 and ostrich Struthio camelus 14 , as well as in Mesozoic ornithurine birds 13 , 24 , The well-developed ICL in the youngest dodo specimens suggests that medullary expansion had already been completed in these individuals During later stages of ontogeny, the fibrolamellar bone, which formed during early ontogeny, is reconstructed and remodeled 13 , The compacta of adult individuals show a well-developed ICL and OCL, both consisting of more slowly formed lamellar bone tissue.

The formation of the OCL tends to occur after the development of the ICL, and only once sexual maturity has been attained 14 , This three-layer arrangement of the tissue in the bone wall in the dodo is similar to that described by Enlow and Brown 26 for a modern hawk Buteo , chicken Gallus , turkey Meleagris , guinea fowl Numida and crow Corvus , and has been shown for other birds such as secretary bird S.

Like large modern flightless birds, e. However, unlike these birds in which this is the predominant tissue of the bone wall, in the dodo this tissue makes up only one third of it.

Slower, more protracted rates of growth during ontogeny have been documented for moas Dinornithiformes 27 , the kiwi Apteryx 29 , and the Late Cretaceous Gargantuavis The slower growth to adult size appears to be related to the lack of predators and to environmental resource stress 22 , 27 , 29 , Interestingly, although the dodo does not exhibit the slow protracted growth of these large island birds, it does appear to have had an extended growth period when reaching skeletal maturity, which is confirmed by the presence of several LAGs in the OCL.

Thus, the dodo experienced rapid growth rates until the attainment of sexual maturity, but thereafter it took several years to attain skeletal maturity. Such an extended, slow growth after sexual maturity might have been possible on a small island like Mauritius 24 where until the arrival of humans, adult birds lacked any natural predators.

Among modern birds, when lines of arrested of growth are present, they tend to be restricted to the OCL However, terrestrial birds on islands, like the kiwi 29 or Dinornithiformes 27 , have several LAGs throughout the cortex.

Turvey et al. In addition, the growth lines evident in the insular Myotragus is considered to be the result of resource limitation The tibiotarsus ddtbt08 shows a large area of medullary bone in comparison to the femur ddfem Rent and save from the world's largest eBookstore.

Refresh and try again. Thus, he suggested, that the dodo evolved its reproduction period to coincide with food abundance, following the same reproductive strategy of the solitaire on neighboring Rodrigues Island. Kowthaman Pathmanathan rated it did not like it Mar 12,

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