Veils, mounds, and vesicle aggregates in neurons elongating in vitro

Nuttall, Robert P.; Wessells, Norman K.

doi:10.1016/0014-4827(79)90345-8

Cited by 39 publications

(9 citation statements)

References 31 publications

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“…The membrane components which are mobilized during anesthetic treatment to form swellings are not similar to the structures referred to as 'mounds' [29] or blebs [12] which represent artifacts of glutaraldehyde fixation. The evidence for distinguishing mounds from the swellings observed in this study is as follows: (a) the swellings are easily visualized in the light microscope prior to fixation; (b) the swellings encompass the en tire fiber; (c) the swellings contain a wide variety of membrane components other than agranular vesicles, such as smooth endoplas mic reticulum, autophagic vacuoles, dense core bodies and coated vesicles; and (d) struc tures identical to mounds are occasionally seen in electron micrographs ( fig.9e) but are not located in the swollen regions.…”

Section: Discussionmentioning

confidence: 99%

“…Although vesicles and smooth endoplasmic reticulum are seen throughout the length of the neurite, they are often clustered in expansions along the periphery of the nerve fiber. Some of these swellings have the appearance of varicosities which have been observed in other neurons in culture [16,47], The bags of membraneous sacs, termed 'mounds' [29], are only occasion ally seen.…”

Section: Electron Microscopy O F Neurons Treated With Anestheticmentioning

confidence: 99%

“…Their arrangement is highly irregular as they branch and reconnect through smaller fibers. Occasionally, regions of cytoplasm, termed veils [29], are seen to spread between two microspikes. The surface of the growth cone and the microspikes is smooth in texture and free of obvious membrane expansions.…”

Section: Electron Microscopy O F Neurons Treated With Anestheticmentioning

confidence: 99%

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Effects of Local Anesthetics on Nerve Growth in Culture

Anderson

Bamburg²

1981

Dev Neurosci

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The effects of the tertiary amine local anesthetics, procaine, lidocaine, and tetracaine, on 8-day-old chick embryo dorsal root ganglia cultured in vitro were examined. All three local anesthetics show a sigmoidal dose-response relationship in inhibiting neurite outgrowth in a reversible fashion. The inhibition of growth is independent of the concentration of nerve growth factor and the in vitro culturing conditions. Morphological studies of cells treated with these anesthetics show that low dosages of the drugs (2.25 X10^–3M lidocaine, 2 x 10^–3M procaine, 1 x 10^–4M tetracaine) cause a retraction of the microspikes into the growth cone and the formation of large swellings along the neurite and at the terminus. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) of these regions show that the loss of micro-spikes is concomitant with the loss of the bundles of microfilaments and much of the microfilament network. The large swellings are filled with an extensive array of smooth endoplasmic reticulum and agranular vesicles of various sizes. The microtubules and neurofilaments within the neurite fiber appear unaffected. Treatment with high dosages (5.0 x 10^–3M lidocaine, 5.0 x 10^–3M procaine, 5 ^x 10^–4M tetracaine) results in a rapid wilting of the microspikes followed by retraction of the neurite. The inhibition of neurite outgrowth and the morphological changes induced by local anesthetics on nerves in culture are similar but not identical to those caused by cytochalasin B, colchicine, and the calcium ionophore A23187.

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Section: Discussionmentioning

confidence: 99%

Section: Electron Microscopy O F Neurons Treated With Anestheticmentioning

confidence: 99%

Section: Electron Microscopy O F Neurons Treated With Anestheticmentioning

confidence: 99%

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Effects of Local Anesthetics on Nerve Growth in Culture

Anderson

Bamburg²

1981

Dev Neurosci

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“…The appearance of such images, referred to as mounds, has been suggested to result from fixation procedures (Nuttall & Wessells, 1979). But even if this is the case they are only observed in developing tissues at certain restricted areas.…”

Section: Biochemical Maturationmentioning

confidence: 99%

Functional maturation of motor nerve terminals in the avian iris: ultrastructure, transmitter metabolism and synaptic reliability

Pilar

Tuttle

Vaca

1981

The Journal of Physiology

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SUMMARY1. The transformation of easily fatigued embryonic neuromuscular junctions into highly reliable mature terminals was examined by studying functional and morphological changes during development of the avian iris. The mature ability to follow repetitive electrical nerve stimulation was correlated with the rate of acetylcholine (ACh) synthesis and choline uptake, and with the fine structure of the nerve terminals and the post-synaptic elements.2. The terminals of the ciliary nerve of the chick initially form functional synaptic contacts with the iris muscle at embryonic St. 3 40. At the onset of this period, no Na+-dependent high affinity choline uptake can be demonstrated, and the low level of ACh synthesis present is sensitive to Na+ removal. At St. 36 [3H]ACh synthesis begins to increase, the increment being Na+-dependent.3. ACh synthesis in the embryonic iris was insensitive to a conditioning [K+]o depolarization even as late as St. 43. Just before hatching, depolarization elicits some augmentation in synthesis, but by 2 days ex ovo this release-induced response has increased by an order of magnitude.4. Concurrently with the acquisition of the ability to respond to depolarization with accelerated synthesis, neuromuscular transmission in the iris becomes reliable and secure during stimulation at 20 Hz. Embryonic junctions rapidly block during such stimulation, and the failure is shown to be presynaptic in origin, resulting most probably from failure to sustain adequate levels of transmitter release.5. Ultrastructural examination of the developing ciliary terminals revealed few synaptic vesicles at early stages, and a dearth of other specializations. The sequence of development from these small structurally undistinguished endings to large en plaque junctions completely filled with vesicles was reconstructed and compared to other neuromuscular junctions. Morphological maturation appears progressive with little evidence of discontinuity signalling functional status, but it is only after the terminals enlarge and become closely packed with vesicles that mature synaptic reliability is found.6. The temporal correlation between responsiveness of transmitter synthesis to

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“…Most of our current understanding of growth-cone function has been elucidated by in vitro time-lapse studies [Bray et al, 1978;Letourneau, 1979;Nuttall and Wessells, 1979;Landis, 1983; Bray and Chapman, 19851. Studies of axon extension in vivo have demonstrated that these data are consistent with growthcone behaviour examined in the natural context [Raper et al, 1983;Mason, 1985;Harris et al, 1985; Tosney and Landmesser, 19851.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of behaviour during neuronal morphogenesis in culture

Jacobs

Stevens

1987

Cell Motil. Cytoskeleton

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We report a developmental sequence in the type and frequency of behaviours of neurons differentiating in vitro. We characterised these changes with extensive analysis of time-lapse sequences from both the continuing cell line pheochromocytoma PC12 and primary mixed cell culture of cat and mouse central nervous system. PC12 cells activated by nerve growth factor (NGF) differentiate in a uniform and synchronous manner. This allowed the first quantification of changes in different neuron behaviours during morphogenesis. Shortly after NGF activation, PC12 cells are highly labile in morphology and exhibit a large variety of morphological behaviours. During the first week of differentiation, the frequency of these behaviours declines, and gross morphology becomes more stable. The frequency of neurite initiation after 1 week in NGF is one-seventh what it was after 2 days in NGF. Over the same period, neurite retraction declines to one-third, and somal migration ceases altogether. Growth-cone activity does not decline during development. These behaviour changes correlate with published data on the differentiation of the neurite cytoskeleton. A qualitatively similar ontogeny was noted in the differentiation of CNS neurons in mixed cell culture. Major differences occur in the relative timing of changes in behaviours. Mature, stable morphology is not detected in these cultures until 7 weeks in vitro.

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Veils, mounds, and vesicle aggregates in neurons elongating in vitro

Cited by 39 publications

References 31 publications

Effects of Local Anesthetics on Nerve Growth in Culture

Effects of Local Anesthetics on Nerve Growth in Culture

Functional maturation of motor nerve terminals in the avian iris: ultrastructure, transmitter metabolism and synaptic reliability

Dynamics of behaviour during neuronal morphogenesis in culture

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