Network vascular

Fig. 2.11 (a) Dissection of VNC — Mouse Lemur (Microcebus murinus). Cl-C3 = Para-septal cartilage bars LV = ventral vein NC = arterioles/capillary network SV = dorsal vein and VNw = ventral wall (from Schilling, 1970). Vomeronasal complex in murine Rodents. Comparison of LS with TS in Rat (b) LS (horizontal). VV = vascular sinus arrow = venous diverticulum = VN lumen and NE = neuroepithelium (from Larriva-Sahd, 1994). (c) TS (coronal). G = glands RFE = non-sensory epithelium (from Mendoza, 1993). 

The lymphatic system of the skin extends up and into the papillary layers of the dermis. A dense, flat meshwork of lymphatic capillaries is found here [11]. Lymph passes into a deeper network at the lower boundary of the dermis. Serum, macrophages, and lymphocytes readily negotiate through the skin s lymphatic and vascular networks. 

Although most drugs are absorbed from the intestine by the blood capillary network in the villi, they can also be taken up by the lymphatic system (an integral and necessary part of the vascular system, the function of which is to collect extra tissue fluid and return it to the vascular compartment), particularly by M cells that reside in the Peyer s patch regions of the intestine. Peyer s patches have also been implicated in the regulation of the secretory immune response. Wachsmann et al. [277] reported that an antigenic material encapsulated within a liposome, when administered perorally, is taken up by these M cells and exhibited better saliva and serum IgA (primary and secondary)... 

The cerebral endothelial cells of the blood-brain barrier originate from the middle germinal sheet of the embryo, the mesoderm [17]. Concomitant with migration and proliferation of capillary endothelial cells during formation of the cerebral vascular network occurs the imprinting of the cells. Thereby, induction by the cellular surrounding plays an important role [18-21], The relevance of the cellular environment for the development of the barrier function of cerebral microvessels was first demonstrated by Stewart and Wiley [22], who transplanted embryonic brain tissue of a quail into embryonic gut tissue of chicken and vice versa. The cerebral transplant was vascularized by intestinal vessels, in which properties of the blood-brain barrier had been induced. In transplanted brain vessels, however, no characteristics of a barrier could be demonstrated, due to the lack of a neuronal environment. These results indicated that the cerebral microvessels are of extraneuronal origin, with properties that are induced by the cellular environment. In addition, brain tissue has the capability to induce blood-brain barrier characteristics also in noncerebral vascular tissue [23],... 

To facilitate international export, mangos are usually disinfested from insect larvae by either chemical or heat treatment. Unfortunately, heat treatments severe enough to kill the larvae can also damage the skin and pulp (mesocarp). Pulp symptoms include impaired starch degradation and development of internal cavities, which are manifest in MRI. Spin-echo image contrast showed the initiation of heat injury around vascular traces in the mesocarp possibly because they form a network for rapid heat transfer and/or retain heat... 

Andreeva ER, Pugach IM, Gordon D and Orekhov AN (1998). Continuous subendothelial network formed by peric3de-like cells in human vascular bed. Tissue Cell 30 127-135. 

Another drug that has been found to have anticytokine activity is pentoxifylline. It was initially characterized as a haemorheologic agent for the treatment of peripheral vascular diseases [141]. In addition, it was also found to be capable of inhibiting the pro-inflammatory actions of IL-1 and TNEa on neutrophil function and cytokine production by monocytic cells [142]. Its mechanism of action is the inhibition of phosphodiesterases, leading to increased intracellular levels of cyclic adenosine monophosphate [143]. Besides its effects on the cytokine network, pentoxifylline also exerted an anti-fibrogenic action in cultures of fibroblasts and in animal models of fibrosis [144] and could therefore be an attractive candidate for targeting hepatic inflammation. 

At this stage, a normal yolk sac presents a robust vascular network (Fig. la). When the yolk sac is positioned to view the ventral side of the embryo, separate origins of the vitelline and umbilical vessels should be evident (Fig. lb). The score is reduced according to deviations from expected morphology. 

Score of 2 If abnormal patterning of the vascular network is noted, the score is assigned a 3 or 2 depending upon the degree of severity. A score of 2 is assigned when there is a moderate reduction (>50%) in vascular branching (Fig. le). 

Score of 1 No obvious vascular network. In such cases, a ring of blood islands is often present around the base of the yolk sac (Fig. If). In addition, the yolk sac is typically not well expanded and its general integrity may appear compromised (such as a darkened or overly translucent appearance or an irregular surface). 

Although the proteins in skin are also composed of about 5% elastic fibers, they do not appear to affect the mechanical properties of the tissue. The elastic fibers are believed to contribute to the recoil of the skin, which gives it the ability to be wrinkle-free when external loads are removed. As humans age, the elastic fiber network of the skin is lost, and wrinkles begin to appear. The mechanical role of the elastic fibers is very different in vascular tissue, however. 

Figure 3.12 The mammalian gastrointestinal tract showing important features of the small intestine, the major site of absorption for orally administered compounds (A) liver (B) stomach (C) duodenum (D) ileum (E) colon (F) longitudinal section of the ileum showing folding, which increases surface area (G) detail of fold showing villi with circular and longitudinal muscles, (H) and (I) respectively, bounded by (J) the serosal membrane (K) detail of villi showing network of (L) epithelial cells, (M) capillaries, and (N) lacteals (O) detail of epithelial cells showing brush border or (P) microvilli. The folding, vascularization, and microvilli all facilitate absorption of substances from the lumen. Source From Ref. 1.

The biosynthesis of flavonoids, stilbenes, hydroxycinnamates, and phenolic acids involves a complex network of routes based principally on the shikimate, phenyl-propanoid, and flavonoid pathways (Figs. 1.35 and 1.36). These biosynthetic pathways constitute a complex biological regulatory network that has evolved in vascular plants during their successful transition on land and that ultimately is essential for their growth, development, and survival [Costa et al., 2003]. 

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