Distribution Of Motor Neurons Research Articles

Cadmium effects on human fetal spinal cord

The biological effects of Cadmium (Cd) on the central nervous system is poorly understood; it is thought that during brain development, when the blood-brain barrier is not well established, Cd may enter the brain and exerts its toxic effects. It has also been suggested that several diseases such as Parkinson disease, amyotrophic lateral sclerosis (ALS) as well as malformations such as spina bifida and forelimb ectrodactyly may be related to Cd exposure. In this study we evaluated the role of Cd in affecting motor neurons and glial cells of the ventral horns of human fetal spinal cord. Sections of human fetal spinal cord (9-12 weeks) were exposed for 24 h to 10 and 100 μM CdCl2. Morphology was evaluated by Haematoxilyn-Eosin staining; distribution and number of motor neurons as well as of glial cells were studied by immunohistochemistry and by Western blot; apoptosis were investigated by TUNEL assay and by Western blot. The cell density in the ventral horns, after CdCl2 treatments, appeared dramatically decreased and the number of apoptotic cells became higher in comparison to control specimens as demonstrated by the high expression level of three different apoptotic markers (NGFR p75, caspase 8 and PARP). The number and the distribution of motor neurons, expressing β tubulin III and positive to choline acetyltransferase, appeared significantly decreased after the treatment with different concentrations of CdCl2. Activation and increase of glial cells were confirmed by the high expression level of Glial Fibrillary Acidic Protein (GFAP). In this study we demonstrate the role of Cd, one of the most diffuse environmental pollutant linked to industrial development, in inducing apoptosis of motor neurons in the ventral horns of human fetal spinal cord. Motor neurons death is accompanied by a surrounding intense glyosis leading to a significant overthrow of the morphological architecture of spinal cord during its development.

Distribution of motor neurons into anatomical groups in the grasshopper metathoracic ganglion

Motor neurons of the main muscles of the hind legs and the hind wings of the grasshopper are distributed into eight anatomical groups within each half of a bilaterally symmetrical segmental ganglion. A group contains 5 to 24 identified motor neurons, accounting for 164 (82 pairs) of the some 200 motor neurons within the population. The motor neurons within a given group may contribute axons to more than one of the lateral nerves, and conversely each lateral nerve contains axons arising from motor neurons in separate groups. Groups may include synergistic and antagonistic motor neurons as well as those that have unrelated functions. The motor neurons of a given muscle may occur together in a single group, or separately in two or more groups. The description of groups provides a way of classifying neurons to simplify and organize the large amount of data on the structure and function of individually identified neurons within the ganglion. The organization of the motor neurons into groups may reflect their developmental origin from individual neuroblasts, and the detailed information about the pattern of groups in the adult thus allows specific predictions to be made about the composition of neurons within neuronal lineages.