Cortical cavity

Bone is divided into trabecular and cortical components, with each further divided into surface bone, bone volume, and bone cavity (marrow compartment). Deposition of americium is assumed to occur from plasma directly to bone surfaces, whereas elimination from bone occurs by transfer from the bone surface or volume to the marrow cavity, and then from the marrow cavity to plasma (Figure 3-6). Transfers of americium within the cortical or trabecular bone compartments are modeled based on assumptions about rates of bone formation and resorption, which are assumed to be vary with age, but are equal within a given age group (Leggett et al. 1982). Movement of americium to the marrow compartment is determined by the bone resorption rate, whereas, movement from the bone surface to the bone volume is assumed to occur by burial of surface deposits with new bone and is determined by the bone formation rate. During growth, bone formation and resorption are assumed to occur at different sites within bone therefore, the rate of removal of americium from the bone surface is approximated by the sum of the bone resorption rate (represented in the model by the movement of americium to the marrow compartment) and the rate of bone... 

Bone. The structure of bone was described in Section 1.5.2. Recall that bone is a composite material, composed primarily of a calcium phosphate form called hydroxyapatite (HA). The major support bones consist of an outer load-bearing shell of cortical (or compact) bone with a medullary cavity containing cancellous (or spongy) bone toward the ends. 

Figure 2. The effect of LSD-25 on the electroencephalogram of the normal unrestrained cat. Recording modes as indicated by connections and electrode position on cortex of cat brain in upper part of picture. Record 4 is derived from hypothalamus. A (control) animal is in quiet waking state. Note alphalike waves in three cortical leads. B records twenty minutes after LSD-25 (15 jug/kg) had been administered into peritoneal cavity, which leads to disappearance of alphas and to arousal pattern. Calibration in microvolts and seconds as indicated (From Bradley and Elkes, 1953). P. B. Bradley and T. Elkes, "The Effects of Some Drugs on the Electrical Activity of the Brain," Brain, Vol. 80, 1957. Reprinted by permission of the authors and the publisher.

Archaeological fragments of bones and teeth take up fluorine from the surrounding soil and accumulate it in their mineral phase when they are exposed to a humid environment. Geological time spans are needed for this process to reach equilibrium and for the fluorine distribution to become uniform. In cortical parts of long bone diaphysis, an initially U-shaped fluorine concentration profile can be observed, which decreases from the outer surface and the marrow cavity towards the inner parts of the bone and carries information on the exposure duration of the buried object in its shape. The time dependence of the profile slope is usually described in a simplified way by a diffusion model. The quantitative mathematical evaluation of these profiles may provide information on the exposure duration and the physical condition of the samples. Therefore, several attempts to use fluorine profiling as a dating method have been undertaken [3,39], The distribution of... 

The cortex forms the bulk of fine animal hairs and is derived from highly differentiated spindle-shaped cells that are densely packed with keratinous proteins. The long axes of the cortical cells are oriented parallel to the fiber length, and elongated cavities near the center of the cells are similarly oriented. These cavities are derived from the nuclei of the developing cells and contain debris usually referred to as nuclear remnants. Between cortical cells there is a layer 250-300 A in thickness which is similar to that found between cuticle cells this also is referred to sometimes as intercellular cement. Many nonkeratinous inclusions are found within the cortical cells and these are believed to be cytoplasmic debris. 

Fig. 3 Vomeronasal system. Schematic representation of a rodent nasal cavity and brain (lateral view). Accessory olfactory bulb (AOB) mitral cells project to vomeronasal and extended amygdala. Inset The VNO is a bilateral tubular structure located at the base of the nasal septum. VSNs that express the same V1R or V2R converge on a small number of glomeruli in the AOB. Sensory neurons located in the apical layer of the epithelium project to the anterior part of the AOB, whereas those present in the basal layer project to the posterior part. MOE main olfactory epithelium, MOB main olfactory bulb, BSTMPM posteromedial bed nucleus of the stria terminalis, MEA medial amygdaloid nucleus, BACfF bed nucleus of the accessory olfactory tract, PMCO posteromedial cortical amygdaloid area...

Trabecular bone is a meshwork of struts giving it a large surface area that is in close contact with the bone marrow cavity for bone turnover and metabolic activity. Cortical bone is formed in layers and is highly calcified (about 80% to 90%). Because of these different structures and environments, trabecular bone is more metabolically active and cortical bone is more structurally strong and protective. 

FGF-1 expression seems to follow a different time course, supporting the notion that its functions in the lesioned brain are distinct from those of FGF-2. Following cortical cavity lesioning, FGF-1 (quantified by ELISA) first became detectable in the cortical lesion fluid 10 days after surgery, and its level increased further until 30 days (Ishikawa et al., 1991b). In contrast, NGF levels increased much more rapidly, with a peak 16 h after lesioning. It is unclear how these data can be reconciled with a study reporting a rapid and drastic increase of FGF-1 in a cortical cavity within 1 h after after trauma (Nieto-Sampedro et al., 1988). 

The bone Is composed of two distinct tissue structures cortical (compact) bone, and trabecular (cancellous) bone (3). Eighty percent of the skeleton is composed of cortical bone (e.g., long bones such as the humerus, radius, and ulna) (4,5), which is a relatively dense tissue (80-90% calcified) (4) that provides structure and support (3). Bone marrow cavities, flat bones, and the ends of long bones are all composed of trabecular bone, which Is considerably more porous (5-20% calcified) (4,5). To maintain healthy, well-mineralized bone, a continuous process of bone resorption (loss of ionic calcium from bone) and formation occurs along the bone surface. Cortical bone Is remodeled at the rate of 3% per year, whereas 25% of trabecular bone, which has considerably higher surface area, is remodeled annually (3). In terms of calcium turnover in bone, approximately 500 mg are removed and replaced on a daily basis. 

There are two t5 es of bone tissue in the human oiganism. Cortical bone thanks to the presence of Haversian channels shows good osteoconductive properties. Thanks to its mechanical properties it can be used in cases when recreation of tridimensional cavities within the facial part of the skeleton is required. As opposed to cortical bone, cancellous bone is extremely rich in osteogenic cells. Living osteoblasts of cancellous bone may survive even for a few hours from the time of harvesting of the tissue early revascularization in closed cavities takes place after 48 hr. The disadvantage of the cancellous bone grafts is their small mechanical endurance. It is also connected with the lack of possibility to use them in case of tridimensional reconstructions [3]. 

Initial mechanical studies with methacrylated monomers show that these polymers demonstrate enhanced mechanical integrity, forming densely crosslinked networks. Moreover, they successfully polymerized in situ in a tibial bone defect, with good adhesion of the polymer to the cortical bone and medullary cavity, as well as minimal adverse tissue reaction to the photopolymerization reaction. ... 

Axial cavities in the basal and middle parts of the stem (the stipe and the basal and middle parts of the rachis) absent state 1 central state 2 cortical state 3. Species for which the character state of this character is coded as state 2 or 3... 

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