Biomaterial Database

Postnatal increase of unmyelinated axon profiles in the feline ventral root L7. 1981

M Risling, and C Hildebrand, and H Aldskogius

The proportion of unmyelinated axon profiles and possible age-related, degenerative and regenerative alterations were studied ultrastructurally in the L7 ventral root of 25 cats ranging form 3 weeks to 11 years of age. For comparison, the ventral root C6 was examined in 5 of these animals. The sections were taken from a level midway between the proximal and distal ends of the roots. The proportion of unmyelinated axon profiles in the L7 ventral root increased from about 14% to around 31% between 4 and 7 months after birth. Simultaneously, the average number of unmyelinated axon profiles per Schwann cell was doubled from 2-3 to 4-5. Thereafter, these figures remained largely unchanged for at least a decade. The total number of myelinated axons was similar in kittens and in cats. In the C6 root the proportion of unmyelinated axon profiles was about 20%, both in kittens and in young or old adult cats. At both segmental levels in the oldest cats, some unmyelinated axons showed degenerative changes and medium-sized and large axons had features characteristic of demyelination and remyelination.

UI	MeSH Term	Description	Entries
D008297	Male		Males
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
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D005260	Female		Females
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
D001369	Axons	Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.	Axon
D012583	Schwann Cells	Neuroglial cells of the peripheral nervous system which form the insulating myelin sheaths of peripheral axons.	Schwann Cell,Cell, Schwann,Cells, Schwann