Search results for "Cell Nucleus"
showing 10 items of 379 documents
Ultrastructural observations on the central innervation of the guinea-pig pineal gland.
1981
In the present study the central innervation of the guinea-pig pineal gland was investigated. The habenulae and the pineal stalk contain myelinated and non-myelinated nerve fibres with few dense-cored and electron-lucent vesicles. Some myelinated fibres leave the main nerve fibre bundles, lose their myelin-sheaths and terminate in the pineal gland. Although direct proof is lacking, the non-myelinated fibres appear to end near the site where the bulk of the myelinated fibres are located. Here a neuropil area exists where synapses between non-myelinated fibre elements are abundant. Neurosecretory fibres were also seen. The results support the concept of functional interrelationships between h…
Electron microscopic study on the larval and adult corpus allatum of Oncopeltus fasciatus dallas (insecta, heteroptera)
1973
1. The ultrastructure of the corpora allata of last larval instars and adults of Oncopeltus was studied. The unpaired gland undergoes submicroscopic alterations and shows signs of degradation in old animals. The organ is partly covered and penetrated by corpus cardiacum tissue. Axons with different types of neurosecretory granules form synaptoid contacts with the corpus allatum cells.
Morphological investigation of the deep pineal of the rat.
1980
The results presented here reveal that in adult Sprague-Dawley and Wistar rats the pineal gland represents a complex rather than a single organ. Regularly one can distinguish (i) pineal tissue in the intercommissural region as a deep pineal, (ii) a superficial pineal, which represents the major part of the pineal complex, and (iii) nearly always a parenchymal stalk of variable length. The volume of the deep pineal with the adjacent parenchymal stalk exhibits great interindividual variation. It amounts to 127 +/- 39 X 10(5) mum3 (mean +/- standard deviation). The histological appearance of the deep and superficial pineal tissue is fairly similar. The intrinsic cells of the deep and superfici…
24-hour-variation of pineal gland volume, pinealocyte nuclear volume and mitotic activity in male Sprague-Dawley rats
1983
In two experiments carried out on two alternate days, the 24-h-rhythmicity of pineal gland volume, pinealocyte nuclear size in cortex and medulla and mitotic activity were studied in male Sprague-Dawley rats, to assess to what extent morphological parameters reflect the pronounced day/night differences in pineal melatonin formation. Pineal volume exhibited statistically significant changes in the second experiment only, with a distinct trough at 6 p.m. Karyometry revealed highly variable patterns. In the first experiment, pinealocyte nuclear changes lacked parallelism in cortex and medulla. The cortex exhibited a bimodal curve with peaks at noon of the first day and at 6 a.m. of the second …
Is Autophagy Altered in the Leukocytes of Type 2 Diabetic Patients?
2015
It is unknown whether autophagy is altered in the leukocytes of type 2 diabetes (T2D) patients and whether oxidative and endoplasmic reticulum (ER) stresses regulate this mechanism. We studied anthropometric and metabolic parameters and evaluated oxidative stress, chromatin condensation, ER stress, and autophagy parameters in leukocytes of 103 T2D patients versus 109 sex- and age-matched controls. Patients showed increases in glucose, insulin, homeostasis model assessment of insulin resistance, and glycated hemoglobin (HbA1c) compared with controls (p < 0.001). Leukocytes displayed enhanced total and mitochondrial reactive oxygen species (ROS), reduced mitochondrial mass, and increased chro…
Fos-like expression and nuclear size in osmotically stimulated supraoptic nucleus neurons
1992
This study has analysed by immunocytochemistry the pattern of expression of Fos-related proteins, as well as variations in nuclear size, after the osmotically induced activation of supraoptic nucleus neurons of the rat. In control rats most supraoptic nucleus neurons were Fos-like negative. After acute and chronic dehydration by salt-loading, the number of Fos-like positive neurons increased dramatically. The level of Fos-like immunoreactivity was higher in chronically stimulated rats, and also the neurons of the ventral region of the supraoptic nucleus were more intensely stained than those of the dorsal region. The karyometric analysis was made on electron micrographs. The mean nuclear pr…
The basic structural lesion of persistent neonatal hypoglycaemia with hyperinsulinism: deficiency of pancreatic D cells or hyperactivity of B cells?
1984
Pancreatic tissue obtained at subtotal pancreatectomy from 15 infants with persistent hypoglycaemia with hyperinsulinism, and autopsy specimens from 23 age-matched normoglycaemic controls, were studied with morphometric methods after immunocytochemical staining of the four main islet cell types (A, B, D and pancreatic polypeptide cells). In three cases, a focal lesion was detected by gross examination. Macroscopic or microscopic examination did not distinguish the 12 other cases from controls. As found previously, nesidioblastosis was not a specific feature of the pancreas in infantile hypoglycaemia, being observed in age-matched controls as well. In cases with hypoglycaemia the volume dens…
Acute ammonia intoxication induces an NMDA receptor-mediated increase in poly(ADP-ribose) polymerase level and NAD+ metabolism in nuclei of rat brain…
2004
Acute ammonia toxicity is mediated by excessive activation of NMDA receptors. Activation of NMDA receptors leads to activation of poly(ADP-ribose) polymerase (PARP) which mediates NMDA excitotoxicity. PARP is activated following DNA damage and may lead to cell death via NAD+ and ATP depletion. The aim of the present work was to assess whether acute ammonia intoxication in vivo leads to increased PARP in brain cells nuclei and to altered NAD+ and superoxide metabolism and the contribution of NMDA receptors to these alterations. Acute ammonia intoxication increases PARP content twofold in brain cells nuclei.NAD+ content decreased by 55% in rats injected with ammonia. This was not due to decre…
Dynamic Tuning of Viscoelastic Hydrogels with Carbonyl Iron Microparticles Reveals the Rapid Response of Cells to Three-Dimensional Substrate Mechani…
2021
Current methods to dynamically tune three-dimensional hydrogel mechanics require specific chemistries and substrates that make modest, slow, and often irreversible changes to their mechanical properties, exclude the use of protein-based scaffolds, or alter hydrogel microstructure and pore size. Here, we rapidly and reversibly alter the mechanical properties of hydrogels consisting of extracellular matrix proteins and proteoglycans by adding carbonyl iron microparticles (MP) and applying external magnetic fields. This approach drastically alters hydrogel mechanics: rheology reveals that application of a 4,000 Oe magnetic field to a 5 mg/mL collagen hydrogel containing 10 wt% MPs increases th…
Cytochalasin B selectively releases ovalbumin mRNA precursors but not the mature ovalbumin mRNA from hen oviduct nuclear matrix
1987
Hen oviduct nuclear matrix-bound mature ovalbumin mRNA is released from the matrix in the presence of ATP, while the ovalbumin mRNA precursors remain bound to this structure. Detachment of the mature mRNA from the matrix by ATP as well as ATP-dependent efflux of mRNA from isolated nuclei were found to be inhibited by cytochalasin B. On the other hand, in the absence of ATP, cytochalasin B exclusively caused the release (and nucleocytoplasmic efflux) of the ovalbumin messenger precursors, but not of the mature mRNA. After cytochalasin B treatment, actin could be detected in the matrix supernatant. Phalloidin which stabilizes actin filaments did not cause RNA liberation in the absence of ATP,…