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The relation between number of myelin lamellae and axon size in the CNS was examined by electron microscopy of spinal cord white matter fibres in different vertebrate species (cat, rabbit, guinea pig, rat, mouse, frog and perch). The results show that the number of myelin lamellae increases with increasing axon size in a non-linear fashion. Below an axon(More)
The axolemmal ultrastructure of nerve fibres within the retina-optic nerve junction (ROJ) from adult rats was examined by freeze-fracture electron microscopy. In the juxtaocular (proximal) region of the ROJ, all fibres are unmyelinated. The axons generally have a membrane ultrastructure similar to that of retinal nerve fibre layer axons, with a high density(More)
(1) Lamellated glial sheaths surrounding axons, and electrogenetically active axolemmal foci have evolved independently in widely different phyla. In addition to endowing the axons to conduct trains of impulses at a high speed, myelination and node formation results in a remarkable saving of space and energy. This is particularly important in the CNS, where(More)
The postnatal differentiation of rat optic nerve fibres was examined by transmission electron microscopy. The results show that many early developing axons contain clusters of vesiculotubular profiles prior to myelination. At places vesicular elements appear to fuse with the axolemma, and, in addition, some axons exhibit deep axolemmal invaginations and(More)
(1) Although our knowledge on teeth and tooth nerves has increased substantially during the past 25 years, several important issues remain to be fully elucidated. As a result of the work now going on at many laboratories over the world, we can expect exciting new findings and major break-throughs in these and other areas in a near future. (2) Dentin-like(More)
Human chromosome 16 features one of the highest levels of segmentally duplicated sequence among the human autosomes. We report here the 78,884,754 base pairs of finished chromosome 16 sequence, representing over 99.9% of its euchromatin. Manual annotation revealed 880 protein-coding genes confirmed by 1,670 aligned transcripts, 19 transfer RNA genes, 341(More)
The size spectra of unmyelinated, ensheathed and initially myelinating CNS axons were examined by electron microscopy in the spinal cord ventral funiculus and the corpus callosum of the cat during development. The first myelin sheaths appeared 4 weeks before and 3 weeks after birth in the spinal and callosal areas, respectively. De novo myelination had(More)
Through small longitudinal incisions in the ventral funiculus of the adult cat spinal cord the intramedullary portions of motoraxons forming the L7 ventral root were divided. The animals were sacrificed by glutaraldehyde-perfusion 1-15 weeks postoperatively. In some cases this was preceded by HRP injection into large L7 ventral horn neurons. Sections from(More)
The size, distribution, and number of nerve fibers and neuronal perikarya in the L7 spinal roots and ganglia of adult cats were examined 35, 90, and 190 days after ipsilateral sciatic nerve resection. With increasing survival time the size spectra of myelinated ventral root nerve fibers showed a progressive flattening of the alpha peak. In the dorsal roots(More)
The relation between the number of myelin lamellae (nl) and axon size (d) was examined in the developing and adult feline inferior alveolar nerve (IAN). The internodal lengths (L) and total diameters (D) were measured on teased IAN specimens from kittens and cats. The results show that relations nl/d and L/D principally similar to those in young adult cats(More)