Cortical shell

BBB-RNA must be isolated for molecular cloning and analysis of BBB-specific transcripts, and several methods for isolating BBB-poly (A+) mRNA in one or more steps have been described [68]). Li et al. recently reported that they obtained yields of 12 pg poly (A+) mRNA from a single bovine cortical shell and 3.2 pg poly (A+) mRNA from the pooled cerebral hemispheres of 21 rats [70]. 

In mesenchymal cells, in addition to the actin cortical shell, myosin can be found in elongated actin structures termed stress fibers. Stress fibers typically are attached at one end to a focal adhesion site, and the other end may terminate in the cortical shell or another focal contact [26, 80]. Myosin is also present in stress fibers, and upon stimulation induces contraction of the stress fibers [5, 78, 117, 127]. 

Waugh, R. and Evans, E.A. 1979. Thermoelasticity of red blood cell membrane. Biophys. J. 26 115-132. Waugh, R.E. and Marches , S.L. 1990. Consequences of structural abnormalities on the mechanical properties of red blood cell membrane. In Cellular and Molecular Biology of Normal and Abnormal Erythrocyte Membranes, C.M. Cohen and J. Palek, eds. pp. 185-199, Alan R. Liss, New York, NY. Yeung, A. and Evans, E. 1989. Cortical shell-liquid core model for passive flow ofliquid-like spherical cells into micropipets. Biophys. J. 56 139-149. 

Distinction must be made between cortical and cancellous bone structures. The harder cortical outer layer carries the bulk of the loading in bones. Although one should not neglect the cancellous bone, it must be recalled that during femoral implant procedures for hip implants, the cancellous canal is reamed out to the cortical shell prior to fitting the metal implant. 

Yeung, A. and Evans, E. 1989. Cortical shell-liquid core model for passive flow of liquid-like spherical cells into micropipets. Biophys. J. 56 139-149. 

As mentioned before, tibia was considered as a cortical shell and the spongy part was ignored. Three different mechanical properties, i.e. elastic isotropic elastic but transversely isotropic and viscoelastic properties were considered for the bone tissue in order to investigate tibia s behavior under the impact loading. 

On the macroscale structure, two distinct bone types can be identified, namely, cancellous and cortical bone. Cortical bone is the dense bone tissue, with low porosity, that forms the shell surrounding bones, whereas the interior part of bone, enclosed by the cortical shell, is filled with cancellous bone that is metabolically more active, remodeled more often and composed of trabecular struts that form the porous structure filled with marrow (Rho et al., 1998). 

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. 

The NAc core and the shell show differences in their input-output organization. For example, although hippocampal projections reach both the core and the shell, the ventral subiculum projects to the shell, whereas the dorsal subiculum projects to the core. Different regions of the prefrontal cortex also target differentially the shell and core the prelimbic area projects to the core, whereas the infralimbic and piriform cortices project to the shell (Berendse et al., 1992). Amygdaloid fiber subsets are also differentially distributed to the two main NAc territories. 

At variance with the ultrastructural features observed in the NAc shell, dopaminergic axon terminals and boutons of thalamocortical axons deriving from the thalamic paraventricular nucleus were not found to converge on the same structures, such as dendritic shafts or spines (Pinto et al., 2003). Also the terminals of hippocampal fibers did not show obvious synaptic relationship with dopaminergic terminals in the prefrontal cortex (Carr and Sesack, 1996), indicating a segregation of different sets of cortical inputs. 

But there are also long-term stresses that may damage the brain and the immune system over time. This happens when our brains remain on orange alert, when we feel helpless, perhaps when we have been ill and when worry and grief consume us. When that happens, we release another set of hormones, the best studied of which is called cortisol. We release this hormone from the cortical (outer shell portion) of our adrenal glands and pump it into our bloodstream. 

Contraction in amoeboid cells makes use of nonmuscle forms of myosin type II whieh form bipolar thiek filaments in the cytoplasm and in association with the actin filaments [23, 54]. In Dictyostelium, actin filaments form a eortieal shell directly under the plasma membrane, with random orientation of the filaments [132]. Activation of myosin contractile activity by phosphorylation of the myosin light ehain protein results in contraction of the cortical network [54, 110], It is unclear whether this contraetion is uniform throughout the eell or whether there is spatial regulation of the activity. In polarized motile Dictyostelium cells, myosin is concentrated at the rear of the cell [31], which could maintain the polarization, while a myosin heavy chain kinase (which phosphorylates the myosin heavy chain protein and inhibits thick filament formation), is localized at the front of the cell. 

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