Development of the nervous system

The development of the nervous system involves many complex interactions between cells, and a large number of genes must be involved in its development. A description of its development requires a knowledge of the cell migrations that lead to its organisation. A number of methods have been used to produce fate 

The role in development of many of the homeo-domain-containing genes is not known, and much of the work recently carried out is aimed at a temporal 

Msx-1 and Msx-2 genes, thought to be involved in short-range epithelial-mesenchymal interactions in developing limb buds (Section 12.4), are also differentially expressed during chick craniofacial development (Nishikawa et al, 1994). Msx-2 has a broader, more intensive expression in the lateral 

Msx-1 is widely expressed in the stage 6 embryo, including the primitive streak. At stage 11, it is detected in the neural crest at the midbrain level (Suzuki et al, 1991). 

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Ephrins are a group of membranous ligands, which function through a family of receptor tyrosine kinases (Ephs). Ephrin/Eph-mediated signaling processes are involved in morphogenetic processes taking place e.g. during the development of the nervous system or the vasculature. 

Acetylcholine, acetylcholinesterase, and butyrylcholinesterase are involved in the development of the nervous system (Brimijoin and Koeninsberger 1999 Layer 1990 Layer and Willbold 1994) some of this development is not complete until adulthood. Therefore, toxic chemicals acting on these substances could cause deleterious developmental effects in addition to the typical physiological effects already discussed. 

The first report of the action of a chemokine on neurons was published in 1993. The study demonstrated that IL-8 could increase the survival of cultured neurons (Araujo and Cotman, 1993). However, as can be appreciated from its name, IL-8 was not known to be a chemokine at that time and was instead classed as an interleukin. Indeed, the expression of chemokine receptors by neurons was not generally appreciated until around 1997/1998 when several reports suggested this. These reports included observations of the expression of chemokine receptors by neuronal cell lines (Hesselgesser et al. 1997), primary cultures of neurons (Meucci et al. 1998 Ohtani et al. 1998), and in brain sections from HlV-1, Alzheimer s disease, and other patients (Horuk et al. 1997 Westmoreland et al. 1998 Xia et al. 1997). Furthermore, data were obtained, suggesting functions for chemokine signaling in the development of the nervous system (Zou et al. 1998) as well as in neuronal survival and communication (Giovannelli et al. 1998 Meucci et al. 1998). 

While each set of cytoskeletal elements has a distinctive spectrum of composition, stability and distribution, all three interact with each other. They have complementary functions and may be coordinately regulated. Such interactions can be seen during development of the nervous system, in mature neuron/glia interactions and in neuropathologies. 

A central role for neural stem cells in the development of the nervous system is becoming clear. During embryo-logical development, the nervous system originates from... 

Black JE. Environment and development of the nervous system. In Gallagher M, Nelson RJ (eds), Handbook of Psychology Biological Psychology, Volume 3. Hoboken, NJ John Wiley Sons, 2003, pp 655-668. 

This helps prevent neurologic effects during development of the nervous system. 

Oppenheim, R. W., Cell death during development of the nervous system. Annu. Rev. Med. 14, 453-501 (1991). 

Neuronal cell death is required for the development of the nervous system. However, recent studies suggest that neurons die from programmed cell death (apoptosis) in brains deprived of oxygen by stroke [14] and trauma [15], and in the brains of Alzheimer s patients [16], Therefore, prevention of neuronal apoptosis has been considered to be a desirable therapeutic strategy for treating such neurodegenerative diseases, although the value of this approach is not yet evident. We have recently reported that crocin suppresses tumor necrosis factor (TNF)-a-... 

Myelination is an essential step in the development of the nervous system of higher animals, which occurs early in life, and is completed within a relatively short period. The central nervous system of the rat and mouse, for example, is myelinated most actively between the 10th and 20th day after birth (1). 

The embryonic development of the nervous system is one of the most interesting processes of ontogenesis, and its study has also been one of the richest sources of information on the strategies that embryos adopt to solve their problems (Bonner, 1988 Edelman, 1988). 

Example 3 the development of the nervous system In some animals everything that neurons do is genetically programmed for life, but in many more cases neural development is neatly discontinuous after an initial phase where the fate of neurons is irrevocably fixed (usually by the time and place of their birth in the neural tube), there comes a second phase where the survival of neurons depends upon the molecules that neural extensions happen to encounter during their exploration of the body. 

Choline is an essential component of phospholipids - phosphatidylcholine (lecithin) is the major phospholipid in cell membranes and sphingomyelin is important in the nervous system. Acetylcholine is a transmitter in the central and parasympathetic nervous systems and at neuromuscular junctions, and has a role in the regulation of differentiation and development of the nervous system (Biagioni et al., 2000). Acetylcholine is also synthesized in mononuclear lymphocytes, where it has an autocrine or paracrine role in regulating immune function (Fujii and Kawashima, 2001). 

We have already alluded to the fact that the NGF-activated p75 4TR receptor is a potential death receptor, like other members of the TNF family of receptors. Evidence is now becoming available that NGF-dependent activation of p75 s can initiate ceU death and apoptosis, whereas NGF and neurotrophin-binding to TRKs (growth-factor tyrosine-kinase-type receptors) has the opposite effect and prevents cell death. Thus, early in development, endogenous NGF causes the death of neurons that express p75 4TR whereas cells that express TRK receptors are not affected and survive. Thus, the fate of developing neurons depends on the type of the receptor e3q>ressed.55 This points to the central role of programmed ceU death in the development of the nervous system.5 ... 

Nerve cells are known to elaborate proteins that guide early development of the nervous system and in later life play a role in cell repair and regeneration. A purine that crosses the blood-brain barrier has shown activity similar to those endogenous factors in vitro as in in vivo models of nerve damage. Conjugate addition of adenine to ethyl acrylate in the presence of base leads to the ester (106). Reaction of that product with sodium... 

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