scholarly journals Two populations or granular vesicles in constricted post-ganglionic sympathetic nerves.

1975 ◽  
Vol 245 (3) ◽  
pp. 727-735 ◽  
Author(s):  
D R Tomlinson
Keyword(s):  
Sympathetic Nerves ◽  
Granular Vesicles ◽  
Two Populations

The accumulation of noradrenaline in constricted sympathetic nerves as studied by fluorescence and electron microscopy

1967 ◽  
Vol 167 (1008) ◽  
pp. 282-292 ◽  
Keyword(s):  
Sympathetic Nerves ◽  
Close Correlation ◽  
Electron Microscopic ◽  
Hypogastric Nerve ◽  
Fluorescent Material ◽  
Dense Cores ◽  
Fluorescence And Electron Microscopy ◽  
Granular Vesicles ◽  
Electron Dense Core ◽  
Microscopic Findings

The effects of constricting post-ganglionic sympathetic nerves have been studied in the cat splenic nerve and guinea-pig hypogastric nerve. The results obtained using a fluorescence method for the histochemical localization of noradrenaline have been compared with electron microscopic findings. A close correlation was found between the accumulation of fluorescent material, attributable to noradrenaline, and of vesicles with an electron dense core (granular vesicles) believed to contain noradrenaline, proximal to the constriction in these nerves. This accumulation of noradrenaline was visible by 1 h after operation and increased rapidly in amount during the succeeding hours. It apparently reached a maximum after approximately 2 days and was found in what appeared to be newly formed axons 3 to 4 days after operation. Reserpine reduces the fluorescence and the number of vesicles with electron dense cores which accumulate proximal to the constriction. It is suggested, (1) that the fluorescent material is due, at least in part, to the presence of the granular vesicles, and (2) that the constriction has blocked the normal proximo-distal movement of noradrenaline which is believed to occur in post-ganglionic sympathetic axons.

An electron microscopic study of the early changes distal to a constriction in sympathetic nerves

1969 ◽  
Vol 172 (1026) ◽  
pp. 53-63 ◽  
Keyword(s):  
Endoplasmic Reticulum ◽  
Degenerative Change ◽  
Sympathetic Nerves ◽  
Ultrastructural Changes ◽  
Electron Microscopic ◽  
Postoperative Changes ◽  
Differential Movement ◽  
Granular Vesicles ◽  
Electron Dense Core ◽  
Myelin Figures

The ultrastructural changes distal to a constriction in unmyelinated postganglionic sympathetic axons have been studied in the cat splenic and hypogastric nerves at intervals up to 24h after operation. Since the immediate postoperative changes were identical with those found proximal to the lesion it was concluded that they were due to the mechanical effects of tying the ligature. Within a few hours of operation there was an accumulation of organelles immediately distal to the constriction. At all times this was greatest within 0.5 mm of the lesion and only rarely extended beyond the first 1 mm even after 24h. The organelles which accumulated included mitochondria, many of which were swollen, pleomorphic myelin figures, multi-vesicular bodies, agranular vesicles and vacuoles of various sizes. Vesicles with an electron dense core, i.e. granular vesicles did not accumulate distal to the constriction. Further from the constriction focal accumulations of some structures, in particular mitochondria and myelin figures, did occur but they were rare. In this part of the nerve there was generally a diminution in the number of organelles, and a marked alteration in the axonal morphology. Alternating swollen and narrow regions were common, and many axons were very irregular as if ‘collapsing’. While filaments and occasionally fine tubules persisted in some of these axons up to 24h after operation, there was a reduction in the endoplasmic reticulum. These findings are compared with those seen proximal to the constriction. Although there were some similarities, the absence of granular vesicles, the decrease in the axonal endoplasmic reticulum and the ‘collapse’ of the axons due to the decrease in their contents were notable differences. It is suggested that there is a differential movement of axoplasm and organelles distal to the constriction. Thus while granular vesicles and some axoplasm continue to move towards the periphery, mitochondria and a part of the axoplasm migrate proximally to the site of axonal injury and the region of maximal degenerative change. The movement of mitochondria is considered to indicate a reaction to injury rather than supporting the view that retrograde axoplasmic flow occurs in normal axons.

Human Neurofibromas in Co-Culture with Mouse Neurons

1982 ◽  
Vol 40 ◽  
pp. 194-195
Author(s):  
R.L. Martuza ◽  
T. Liszczak ◽  
A. Okun ◽  
T-Y Wang
Keyword(s):  
Schwann Cell ◽  
Schwann Cells ◽  
Genetic Disorder ◽  
Cranial Nerves ◽  
Sympathetic Nerves ◽  
Acoustic Neuromas ◽  
Spinal Roots ◽  
Neural Crest Origin ◽  
Multiple Abnormalities ◽  
Other Neoplasms

Neurofibromatosis (NF) is an autosomal dominant genetic disorder with a prevalence of 1/3,000 births. The NF mutation causes multiple abnormalities of various cells of neural crest origin. Schwann cell tumors (neurofibromas, acoustic neuromas) are the most common feature of neurofibromatosis although meningiomas, gliomas, and other neoplasms may be seen. The schwann cell tumors commonly develop from the schwann cells associated with sensory or sympathetic nerves or their ganglia. Schwann cell tumors on ventral spinal roots or motor cranial nerves are much less common. Since the sensory neuron membrane is known to contain a mitogenic factor for schwann cells, we have postulated that neurofibromatosis may be due to an abnormal interaction between the nerve and the schwann cell and that this interaction may be hormonally modulated. To test this possibility a system has been developed in which an enriched schwannoma cell culture can be obtained and co-cultured with pure neurons.

Comparison of Principal Component Solutions in Two Populations

Methodology ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Gregor Sočan
Keyword(s):  
Simulation Study ◽  
Principal Components ◽  
Common Factor ◽  
Principal Component ◽  
Component Model ◽  
Bootstrap Procedure ◽  
Factor Loadings ◽  
Component Loadings ◽  
Principal Component Model ◽  
Two Populations

Abstract. When principal component solutions are compared across two groups, a question arises whether the extracted components have the same interpretation in both populations. The problem can be approached by testing null hypotheses stating that the congruence coefficients between pairs of vectors of component loadings are equal to 1. Chan, Leung, Chan, Ho, and Yung (1999) proposed a bootstrap procedure for testing the hypothesis of perfect congruence between vectors of common factor loadings. We demonstrate that the procedure by Chan et al. is both theoretically and empirically inadequate for the application on principal components. We propose a modification of their procedure, which constructs the resampling space according to the characteristics of the principal component model. The results of a simulation study show satisfactory empirical properties of the modified procedure.

Molecular phylogeny and taxonomic evaluation of the genus Asaccus Dixon and Anderson, 1973 (Reptilia: Phyllodactylidae) in Iran

2020 ◽  
pp. 207-214
Author(s):  
Akbar Fattahi
Keyword(s):  
Molecular Phylogeny ◽  
Nuclear Gene ◽  
Genetic Distances ◽  
Genetic Lineage ◽  
New Taxon ◽  
Zagros Mountains ◽  
Relict Species ◽  
Taxonomical Revision ◽  
Two Populations ◽  
Taxonomic Evaluation

The Iranian species of the phyllodactylid geckos of the genus Asaccus are found only in the valleys of the Zagros Mountains, a region which represents an important area of endemism in western Iran. Recently, many relict species have been described from the central and southern parts of the Zagros Mountains, which were previously known as A. elisae. The recent descriptions of species within this complex suggest that diversity within the genus may be higher than expected and that its taxonomy and systematics should be revised. In the present study, phylogenetic relationships within the genus Asaccus were evaluated using two mitochondrial and one nuclear gene. Genetically, the genus shows high levels of variability. The molecular phylogeny of the genus suggests the presence of three main clades along the Zagros Mountains with the southern population (from the Hormozgan province) and one clade (A. sp8 and A. sp9) being sister taxon to A. montanus from UAE. The remaining samples are separated into two reciprocally monophyletic groups: the northern (Kurdistan, Kermanshah and Ilam provinces) and the central (Lorestan, Khuzestan, Kohgilouye-Bouyer Ahmad and Fars provinces) Zagros groups. The results of the present study suggest that populations attributed to A. elisae in Iran correspond to distinct lineages with high genetic distances. In brief, our results suggest that the genus needs a major taxonomical revision The Arabian origin of the genus has not been confirmed, because two populations from Zagros were located within the A. montanus, A. gallagheri and A. platyrhynchus clade. Further morphological analyses are needed to systematically define each genetic lineage as a new taxon.

Comparing Genetic Variation within Red Winter Wheat Populations with and without Image-Based Optical Sorter Selection

2019 ◽  
Vol 9 (2) ◽  
pp. 266-277
Author(s):  
Hussein M. Khaeim ◽  
Anthony Clark ◽  
Tom Pearson ◽  
Dr. David Van Sanford
Keyword(s):  
Genetic Variation ◽  
Fusarium Head Blight ◽  
Heading Date ◽  
Fusarium Head Blight Resistance ◽  
Gibberella Zeae ◽  
Mass Selection ◽  
Head Blight ◽  
Red Winter Wheat ◽  
Two Populations ◽  
Head Scab

Head scab is historically a devastating disease affecting not just all classes of wheat but also barley and other small grains around the world. Fusarium head blight (FHB), or head scab, is caused most often by Fusarium graminearum (Schwabe), (sexual stage – Gibberella zeae) although several Fusarium spp. can cause the disease. This study was conducted to determine the effect of mass selection for FHB resistance using an image-based optical sorter. lines were derived from the C0 and C2 of two populations to compare genetic variation within populations with and without sorter selection. Our overall hypothesis is that sorting grain results in improved Fusarium head blight resistance. Both of the used wheat derived line populations have genetic variation, and population 1 has more than population 17. They are significantly different from each other for fusarium damged kernel (FDK), deoxynivalenol (DON), and other FHB traits. Although both populations are suitable to be grown for bulks, population 1 seems better since it has more genetic variation as well as lower FDK and DON, and earlier heading date. Lines within each population were significantly different and some lines in each population had significantly lower FDK and DON after selection using an optical sorter. Some lines had significant reduction in both FDK and DON, and some others had either FDK or DON reduction. Lines of population 1 that had significant reduction, were more numerous than in population 17, and FDK and DON reduction were greater.

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