Biomaterial Database

Differential effects of aging on motoneurons and peripheral nerves innervating the hindlimb and forelimb muscles of rats. 1995

K Hashizume, and K Kanda

Department of Central Nervous System, Tokyo Metropolitan Institute of Gerontology, Japan.

We examined the number and size of ulnar (forelimb) and medial gastrocnemius (MG, hindlimb) motoneurons in middle-aged (9 months of age) and aged (27 months of age) male Fischer 344 rats. Morphological properties of the ulnar and the MG nerves were also studied. No significant difference was found in the mean number of the ulnar motoneurons between the two age groups, while that of MG motoneurons was significantly less in aged animals. A decrease in the number of myelinated fibers (including both afferent and efferent fibers) in the ulnar nerves was less than that in the MG nerves, although the age difference was not significant in either of the nerves. Soma atrophy of aged motoneurons was found in both MG and ulnar motor nuclei. The mean fascicular areas and myelinated fiber diameters were significantly increased in both the MG and the ulnar nerves in aged rats, but these were less pronounced for the ulnar nerve. The results indicate that most ulnar motoneurons, unlike MG motoneurons, survive at least to the age of 27 months. Morphological changes in the peripheral nerves were also less for the ulnar nerve than for the MG nerve. Thus, we conclude that the effects of aging on motoneurons and peripheral nerves innervating MG muscle of the hindlimb are greater than those innervating forelimb muscles.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
D009413	Nerve Fibers, Myelinated	A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.	A Fibers,B Fibers,Fiber, Myelinated Nerve,Fibers, Myelinated Nerve,Myelinated Nerve Fiber,Myelinated Nerve Fibers,Nerve Fiber, Myelinated
D010525	Peripheral Nerves	The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.	Endoneurium,Epineurium,Perineurium,Endoneuriums,Epineuriums,Nerve, Peripheral,Nerves, Peripheral,Perineuriums,Peripheral Nerve
D011916	Rats, Inbred F344	An inbred strain of rat that is used for general BIOMEDICAL RESEARCH purposes.	Fischer Rats,Rats, Inbred CDF,Rats, Inbred Fischer 344,Rats, F344,Rats, Inbred Fisher 344,CDF Rat, Inbred,CDF Rats, Inbred,F344 Rat,F344 Rat, Inbred,F344 Rats,F344 Rats, Inbred,Inbred CDF Rat,Inbred CDF Rats,Inbred F344 Rat,Inbred F344 Rats,Rat, F344,Rat, Inbred CDF,Rat, Inbred F344,Rats, Fischer
D002452	Cell Count	The number of CELLS of a specific kind, usually measured per unit volume or area of sample.	Cell Density,Cell Number,Cell Counts,Cell Densities,Cell Numbers,Count, Cell,Counts, Cell,Densities, Cell,Density, Cell,Number, Cell,Numbers, Cell
D005552	Forelimb	A front limb of a quadruped. (The Random House College Dictionary, 1980)	Forelimbs
D006614	Hindlimb	Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)	Hindlimbs
D000375	Aging	The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.	Senescence,Aging, Biological,Biological Aging
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia