Remodelling Haversian

In attempting to reconcile these findings, it should be pointed out that rats may not be appropriate models for the study of calcium metabolism in humans. Unlike humans, the rat does not undergo epiphyseal plate closure and does not have a significant haversian remodeling sequence (21) Furthermore, rats excrete only l-270 of their calcium intake in their urine whereas humans excrete approximately 20-30% or more. This fact is especially significant, since most of the known effects of phosphates on calcium retention in humans are effected by alterations in urinary calcium. 

Aitken MJ (1990) Science-based Dating in Archaeology. Longman Archaeology Series, Longman, London Anderson C, Danylchuk KD (1977) The effect of chronic low level lead intoxication on the Haversian remodeling system in dogs. Lab Invest 37 466-469... 

Vincentelli and Grigorov [35] examined the effect of Haversian remodelling on the tibia. The specimens they reported were almost entirely primary or Haversian, with few specimens having a scattering of secondary osteons. [Unfortunately they probably (it is not clear) allowed their... 

Vincentelli, R., and Grigorov, M. (1985) The effect of haversian remodeling on the tensile properties of human cortical bone. J. Biomeck, 18, 201-207. 

Compact bone like long bones, most abundant among archaeological bone remains, shows basically two different parts a central one called diaphysis, mainly composed of compact bone, and two extremities called epiphysis which are more porous. It contains a fundamental substance - a mixture of the organic and mineral phase - and cells that remodel continuously the bone material as well as the so-called Haversian systems containing channels that provide the nutrition to the bone cells as they accommodate blood vessels and nerves. The Haversian channels exhibit diameters between 10 and 70 pm [26], The periosteum closes the bone at its outside and the medullar cavity at the inside accommodating the bone marrow [40],... 

Cortical bone, also called compact or lamellar bone, is remodelled from woven bone by means of vascular channels that invade the embryonic bone from its periosteal and endosteal surfaces. It forms the internal and external tables of flat bones and the external surfaces of long bones. The primary structural unit is an osteon, also known as a Haversian system, a cylindrical shaped lamellar bone surrounding longitudinally oriented vascular channels (the Haversian canals). Horizontally oriented canals (Volkmann canals) connect adjacent osteons. The mechanical strength of cortical bone results from the tight packing of the osteons. 

Anderson C, Danylchuk KD. 1979. The effect of chronic excess zinc administration on the haversian bone remodelling system and its possible relationship to "Itai-ltai" disease. Environ Res 20 351-357. 

Compact bone is found in the cylindrical shells of most long bones in vertebrates. It often contains osteons which consist of lamellae that are cylindrically wrapped around a central blood vessel (Haversian system or secondary osteon). These secondary osteons form during bone remodeling. Studies have shown that the orientation of the collagen fibrils within individual lamellas is a function of external stresses on the bone and adapted to the specific function." " ... 

Cortical tissue is the dense part of bone. As a living entity, this material is able to maintain and adapt its stracture to external physical stimuli [1], The seat of bone remodeling mechanisms corresponds to cyhndrical stractuial elements called osteons. Each osteon is surrounded by a thin layer (cement line) and is centered on Haversian canal which runs primarily in the bone longitudinal axis. The Haversian canals contain the vasculature, the nerves and interstitial fluid. There are also Volkmann canals which are similar to Haversian canals except that they run along the transverse direction of the bone. At a smaller scale, other extravascular pores exist in the solid matrix of the bone forming the la-cuno-canalicular system. This porous network irrigates the mechano-sensitive osteocytes which are believed to play an important role in bone adaptation as stated in recent experimental studies [2,3,4]. 

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