Quantitative relationships between axoplasm and Schwann cell sheath in unmyelinated nerve fibres. An electron microscope study. 1988

E Pannese, and G Arcidiacono, and D Frattola, and L Rigamonti, and P Procacci, and M Ledda
Istituto di Istologia, Embriologia e Neurocitologia, Università di Milano, Italy.

The quantitative relationships between the size of the Schwann cell sheath and that of its related axoplasm were studied by electron microscopy in cross sections of bundles of unmyelinated axons (Remak bundles) of the spinal roots of lizard (Lacerta muralis). It was found that (i) the cross sectional area of the Schwann cell sheath is directly proportional to that of its related axoplasm (correlation coefficient 0.84), and (ii) the ratio between the cross sectional area of the Schwann cell sheath and that of its related axoplasm tends to diminish as the cross sectional area of the latter increases. Thus, under normal conditions, in the bundles of unmyelinated axons of the spinal roots of lizard a quantitative balance exists between the nerve tissue and its associated glial tissue. These results agree with those previously obtained in the myelinated fibres of the same region and in the spinal ganglia of the lizard, gecko, cat and rabbit. Some of the mechanisms probably involved in the control of the quantitative balance between nerve tissue and its associated glial tissue in peripheral nerves are listed.

UI MeSH Term Description Entries
D008116 Lizards Reptiles within the order Squamata that generally possess limbs, moveable EYELIDS, and EXTERNAL EAR openings, although there are some species which lack one or more of these structures. Chameleons,Geckos,Chameleon,Gecko,Lizard
D008854 Microscopy, Electron Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen. Electron Microscopy
D009412 Nerve Fibers Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM. Cerebellar Mossy Fibers,Mossy Fibers, Cerebellar,Cerebellar Mossy Fiber,Mossy Fiber, Cerebellar,Nerve Fiber
D002462 Cell Membrane The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells. Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D003593 Cytoplasm The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990) Protoplasm,Cytoplasms,Protoplasms
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
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
D013126 Spinal Nerve Roots Paired bundles of NERVE FIBERS entering and leaving the SPINAL CORD at each segment. The dorsal and ventral nerve roots join to form the mixed segmental spinal nerves. The dorsal roots are generally afferent, formed by the central projections of the spinal (dorsal root) ganglia sensory cells, and the ventral roots are efferent, comprising the axons of spinal motor and PREGANGLIONIC AUTONOMIC FIBERS. Dorsal Roots,Spinal Roots,Ventral Roots,Dorsal Root,Nerve Root, Spinal,Nerve Roots, Spinal,Root, Dorsal,Root, Spinal,Root, Spinal Nerve,Root, Ventral,Roots, Dorsal,Roots, Spinal,Roots, Spinal Nerve,Roots, Ventral,Spinal Nerve Root,Spinal Root,Ventral Root

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