Time of cell origin and cell death in the avian dorsal motor nucleus of the vagus

Wright, Linda L.

doi:10.1002/cne.901990110

Cited by 20 publications

(4 citation statements)

References 36 publications

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“…3) At the matured stage, neurons are functionally arranged in a hierarchical pattern surrounding the central core. Considering that cell death occurs at later stages in these motor nuclei (McConnell and Sechrist 1980;Wright 1981), it seems likely that these processes are related to neuronal generation/differentiation rather than neuronal death/degeneration. The distribution pattern of the EPSPrelated slow signal in the NTS was simple from the onset of synaptic function, as shown in Fig.…”

Section: How Do the Motor Nuclei Develop Functionally?mentioning

confidence: 99%

Optical Approaches to Functional Organization of Glossopharyngeal and Vagal Motor Nuclei in the Embryonic Chick Hindbrain

Sato

Mochida

Yazawa

et al. 2002

Journal of Neurophysiology

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We investigated the functional organization of the glossopharyngeal and vagal motor nuclei during embryogenesis using multiple-site optical recording with a fast voltage-sensitive dye. Intact brain stem preparations with glossopharyngeal and vagus nerves were dissected from 4- to 8-day-old chick embryos. Electrical responses evoked by glossopharyngeal/vagus nerve stimulation were optically recorded from many loci of the stained preparations. In 4- to 6-day-old preparations, action potential-related fast spikelike signals were detected from the nucleus of the glossopharyngeal nerve and the dorsal motor nucleus of the vagus nerve. Contour line maps of the signal amplitude showed multiple-peak patterns, suggesting that the neurons and/or their activity were not uniformly distributed within the nuclei at early developmental stages. As development proceeded from 4 to 6 days, the peaks fused with each other and the number of peaks decreased gradually. In most 7- and 8-day-old preparations, only a single peak was identified in the nuclei, and the distribution of the signal amplitude formed a layered pattern surrounding the peak-signal area. These results suggest that functional organization of the motor nuclei in the embryonic hindbrain changes dynamically with development, resulting in a rearrangement of functional nuclear cores from multiple-peaks to a single peak.

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Section: How Do the Motor Nuclei Develop Functionally?mentioning

confidence: 99%

Optical Approaches to Functional Organization of Glossopharyngeal and Vagal Motor Nuclei in the Embryonic Chick Hindbrain

Sato

Mochida

Yazawa

et al. 2002

Journal of Neurophysiology

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“…The identification of cells as neuroblasts or young neurons of the developing NA was based on criteria that at least in part, have been used by others for the identification of motor neuroblasts. For the youngest specimens studied, those cells that have migrated out of the ventricular layer into the intermediate layer to form the medial motor column and that constitute the primordial NA and hypoglossal nucleus have somata that are slightly larger than the ventricular cells and other cells in the intermediate layer (Altman and Bayer, 1982;Hamburger, 1975;Heaton and Moody, 1980;McLennan, 1988;Wright, 1981). Most of the NA neuroblasts are more loosely arranged than the adjacent cells, resulting in spaces between cells, which provide for the appearance of a pale staining background (Levi-Montalcini, 1964).…”

Section: Criteria For Identifying Na Neuroblasts and Young Neuronsmentioning

confidence: 99%

Prenatal development of the human nucleus ambiguus during the embryonic and early fetal periods

Brown

1990

Am. J. Anat.

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The ontogenetic development of the nucleus ambiguus was studied in a series of human embryos and fetuses ranging from 3 to 12.5 weeks of menstrual age (4 to 66 mm crown-rump length). They were prepared by Nissl and silver methods. Nucleus ambiguus neuroblasts, whose neurites extend towards and into the IXth and rostral Xth nerve roots, appear in the medial motor column of 4-6-week-old embryos (4.25-11 mm). These cells then migrate laterally (6.5 weeks, 14 mm) to a position near the dorsal motor nucleus of X. At 7 weeks (15 mm), nucleus ambiguus cells begin their migration, which progresses rostrocaudally, into their definitive ventrolateral position. The basic pattern of organization of the nucleus is established in its rostral region at 8 weeks (22.2-24 mm) and extends into its caudal region by 9 weeks (32 mm), when its nearly adult organization is evident. Cells having the characteristics of mature neurons first appear rostrally in the nucleus during the 8.5-9-week period (24.5-32 mm), gradually increase in number, and constitute the entire nucleus at 12.5 weeks (65.5 mm). Definitive neuronal subgroups first appear at 10 weeks (37.5 mm) in the large rostral nuclear region. These features suggest that the human nucleus ambiguus develops along a rostrocaudal temporospatial gradient. Evidence indicates that function of nucleus ambiguus neurons, manifested by fetal reflex swallowing, occurs after the cells migrate into their definitive position, establish the definitive nuclear pattern, and exhibit mature characteristics.

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“…A similar close tem poral relationship between these three processes has also been suggested to be important in the sequence of development in other parts of the nervous system such as the spinal cord [Sims et al, 1981] and the dorsal motor nucleus of the vagus [Wright, 1981]. In the retina, the final gra dient of ganglion cell density between cen tral and peripheral areas may be largely dependent on the spatio-temporal gra dient of ganglion cell histogenesis and dif ferentiation.…”

Section: Development O F Siamese Area Centralismentioning

confidence: 62%

Characteristics of Nasal and Temporal Retina in Siamese and Normally Pigmented Cats; pp. 103–113

Murakami¹,

Sesma²,

Rowe³

1982

Brain Behav Evol

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Properties of ganglion cells in nasal and temporal retina of Siamese and normally-pigmented cats are described. In agreement with earlier reports on normal cats, the somas of both X and Y cells are larger in temporal than in nasal retina, although these differences are not entirely independent of ganglion cell density. Furthermore, the axons of X cells in temporal retina were distinctly faster and larger than those of X cells in nasal retina. Since, in normal cats, almost all nasal X cells project contralaterally and almost all temporal X cells project ipsilaterally, it is difficult to assess independently the effects of retinal location and laterality of projection on either soma size or axon size of nasal and temporal X cells. However, taking advantage of the abnormal pattern of decussation seen in Siamese cats, in which a substantial number of temporal X cells project contralaterally, it is possible to demonstrate that the difference in soma size is independent of laterality of projection and appears to be a function of retinal location, whereas the difference in axon size is a function of laterality of projection and is independent of retinal location. Thus, soma size and axon diameter are at least partially independent. We were unable to obtain clear support for the suggestion that Siamese cats suffer a selective loss of X-type retinal ganglion cells, and an alternative mechanism for the reduced prominence of the area centralis in Siamese cats is proposed. The distinction between developmental mechanisms influencing the prominence of the area centralis and those influencing laterality of projection, as well as the relationship between retinal specializations associated with acuity and specializations associated with binocularity are also considered. The trajectory of axons arising from temporal retina and travelling above or below the area centralis towards the optic disc is described. In normal cats, the general features of this trajectory are the same for ipsilaterally and contralaterally projecting axons, and for axons of all ganglion cell groups. This also appears to be the case in Siamese cats. However, axons from temporal retina show a greater tendency to pass directly over the area centralis in Siamese than in normal cats, and the boundary between the region of temporal retina from which axons pass superior to the area centralis and the region from which they pass inferior to the area centralis may be closer to the vertical meridian in Siamese than in normal cats. These differences in trajectory could lead to a rearrangement of ipsilaterally projecting axons within the optic nerve. In both Siamese and normal cats, a small number of ganglion cells, scattered throughout nasal retina, project ipsilaterally. On the basis of soma size and dendritic morphology, all cells observed in our material can be identified as either alpha or gamma cells. In Siamese cats, such cells are consistently more numerous than in normal cats. In Siamese cats, however, this group of ipsilaterally projecting cells contains a hig...

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Time of cell origin and cell death in the avian dorsal motor nucleus of the vagus

Cited by 20 publications

References 36 publications

Optical Approaches to Functional Organization of Glossopharyngeal and Vagal Motor Nuclei in the Embryonic Chick Hindbrain

Optical Approaches to Functional Organization of Glossopharyngeal and Vagal Motor Nuclei in the Embryonic Chick Hindbrain

Prenatal development of the human nucleus ambiguus during the embryonic and early fetal periods

Characteristics of Nasal and Temporal Retina in Siamese and Normally Pigmented Cats; pp. 103–113

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