Biologic Markers in Reproductive Toxicology (1989) / Chapter Skim
Currently Skimming:
25. Developmental Neurobiology of the Central Nervous System
25. Developmental Neurobiology of the Central Nervous System
Pages 273-280
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 273... ...
Neuronal communication has several important features, including: · The complex cellular architecture of the neuronal system, which involves multiple connections, redundancies, and positive and negative feedback loops. · The synthesis, storage, release, and takeup of multiple neurochemicals in many neurons.
|
From page 274... ...
Neuronal death and migration can be manipulated to cause abnormal development within the CNS, and experimental production of cellular derangements can cause behavioral alterations in animals exposed to toxicants at specific periods of CNS cytomorphogenesis. The initial event of vertebrate CNS development is an alteration in the embryonic surface ectoderm by the chorda-mesoderm or its structural analogue.
|
From page 275... ...
In general, neuroblasts formed in the cerebral cortex conform to the basic pattern, albeit with some exceptions-for example, the Cajal-Retzius cells in layer I How275 ever, in the cortex, cells closest to the central canal migrate, as neuroblasts, out of the primitive ependymal zone earlier than more peripheral cells.
|
From page 276... ...
The oldest cells are deposited as the top row of granule cells in contact with the superficial plexiform layer, and the younger cells end up in the basal layer (Altman and Das, 1966; Jacobson, 1978; Cowan et al., 1980~. NEURODEVELOPMENTAL TOXICOLOGY NEUROCHEMISTRY OF NEURONAL COMMUNICATION Biochemically, the nervous system functions as sets of connecting pathways of cells that send and receive information by releasing specific chemicals that translate changes in the electric properties of cell membranes into intracellular activity of enzymes.
|
From page 277... ...
Neuronal uptake, which is kinetically highly efficient and saturable at low concentrations, can serve several functions, including termination of cell stimulation by removing the neuroactive compound from the receptor, resupply of intracellular pools for later release, and provision of precursors for the synthesis of neurotransmitters, such as choline for acetylcholine, tyrosine for dopamine and norepinephrine, and tryptophan for serotonin. Transport is a critical process in neurons, particularly those with long axonal projections and extensive dendritic arborizations, in which enzymes and other materials synthesized in the cell body must be moved to the terminals.
|
From page 278... ...
B50 PSD 95 Myelin basic protein (MS) Myelin-associated glycoprotein GFAP Brain Tissue Markers Protein III Synapsin I Status of synaptic membranes of CNS neurons Status of synaptic membranes of CNS neurons Status of synaptic membranes of CNS neurons Postsynaptic receptors Status of oligodendroglia and myelin sheath Oligodendroglia Astrocytes (gliomas)
|
From page 279... ...
However, the implications of the biochemical modifications for functional changes, such as neuronal activity in serotoninergic pathways, are not yet clear. Reliable inferences regarding the status of function in pathways that use amino acids cannot be drawn from measurements of peripheral amino acid metabolism.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.