Degenerative Changes In Cells Research Articles

A functional study of uncrossed and crossed pulmonary afferent fibres in the cervical vagus nerves of the cat

The functional distribution of uncrossed and crossed pulmonary afferent fibres in the cervical vagus nerves has been studied in the anaesthetized cat using acute and chronic unilateral pneumonectomized preparations. The heart and lungs were sympathectomized routinely. The vagal afferent pathways of three pulmonary reflexes were investigated: the Hering–Breuer respiratory reflex, the lung inflation cardio-accelerator reflex, and the pulmonary chemoreflex. Inflation of the remaining lung caused temporary inhibition of inspiration. It also resulted in acceleration of the heart, but only when the background cardiac vagal tone was augmented. These respiratory and cardiac responses were abolished in most animals by ipsilateral cervical vagotomy; however, in some, a small response persisted and this was abolished by contralateral vagotomy. Stimulation of pulmonary C-fibre endings with right atrial injections of phenylbiguanide caused a reduction in respiration, bradycardia and systemic hypotension, responses which occurred with a latency of 2.9±0.15 s. They were mostly abolished by ipsilateral cervical vagotomy, but reduced responses persisted in a few animals. The residual responses were abolished by contralateral cervical vagotomy and by selective denervation of the lung. These results indicate that most afferent fibres subserving the three pulmonary reflexes studied run in the ipsilateral cervical vagus, representing the uncrossed pathway. Some afferent fibres, however, cross to the contralateral cervical vagus. Degenerative changes in cells of the contralateral nodose ganglion in chronic unilateral pneumonectomized animals support these findings.

Chapter 18 A systems approach to nerve regeneration

Publisher Summary When injury occurs in the brain or spinal cord, for whatever reason, subsequent degenerative and regenerative events begin to occur in which many cellular and extracellular elements participate. The relative constancies of structural, compositional, and functional features of cells, tissues, and organs in normal mature animals under various environmental conditions are indicative of the existence of remarkable biochemical servomechanisms, which coordinate a variety of complex biosynthetic and degradative pathways and which continuously adjust the rates of entry and exit of substances between the organism and its environment, between extracellular and intracellular compartments of tissues, and between cytosol and the organelles of individual cells. The mechanisms for the regulation of the quantities of individual substances may interact with one another at one or more points. There are examples of coordinate changes in metabolically related constituents and of changes in some cellular constituents without marked changes in others with which the ones that change have known metabolic relations. Pathology in the brain and spinal cord may be characterized by degenerative changes in cells in many regions and may be associated with damage to the microvasculature, the losses of neuronal cells, decreases in neuronal processes in surviving cells, and changes in the relative proportions and functions of various nonneuronal cellular elements.

A cytological study of the net blotch disease of barley caused by Pyrenophora teres

Light and electron microscope studies were made on the penetration and infection of barley leaves by Pyrenophora teres. Both successful and abortive attempts to penetrate the epidermal cells were observed. At successful penetration sites a primary vesicle developed within the epidermal cell, followed by the formation of a secondary vesicle. Failure to breach the epidermal cell wall was associated with the formation of papillae. Subsequent to vesicle formation, in a susceptible interaction, hyphae penetrated through the lower epidermal cell wall and the colonizing hyphae developed intercellularly in the mesophyll tissue. No hyphae were seen to penetrate the mesophyll cells during the early stages of infection, although intracellular hyphae were occasionally observed in senescent cells during later stages. Initially the lesions were clearly delimited. Cells within the developing lesions exhibited various degrees of disruption. Loss of tonoplast integrity appeared to precede swelling and vesiculation of chloroplasts. In many cells complete disorganization of the internal membranes occurred and the cells collapsed. Cells exhibiting these degenerative changes were always in close contact with intercellular hyphae. Subsequent colonization was associated with chlorosis of tissue surrounding the netted lesions. The degenerative changes in cells from this chlorotic tissue were different to those observed in cells within the netted lesion and resembled those which occur during normal leaf senescence. Cells exhibiting these symptoms were not always in contact with the hyphae of the pathogen. These observations are discussed in relation to the role of contact phenomena and toxins in the pathogenesis of this disease.

Corneal response to rigid contact lens wear.

Three adult rhesus monkeys were subjected to 2 and 24 hours of polymethylmethacrylate (PMMA) contact lens wear. The induced corneal changes were examined with the electron microscope. Mild epithelial oedema as well as early degenerative cell changes was present already after 2 hours' wear. Rigid lens wear for 24 hours produced more severe oedema and cell alterations together with premature cell loss and ultimately, in areas of lens bearing, corneal denuding. Only the monkeys wearing contact lenses for 24 hours had significant stromal swelling, which was primarily evident in the posterior region, while the anterior limiting lamina remained unaffected. The stromal swelling was patchy and mainly around keratocytes and between lamellae, while fluid within the lamellae was evident only occasionally in posterior stroma. Changes among keratocytes were evident, especially posteriorly, where reaction was frequently severe. Endothelial reaction was restricted to a limited fluid uptake in the 24-hour-wear experiment. In addition there was in these monkeys an apparent loosening of the endothelial adhesion to the posterior limiting lamina. It is concluded that the oedematous epithelium undergoes cell shrinkage and flattening, which is compensated for by an uptake of fluid. The uptake of fluid maintains the overall normal thickness of the epithelium. The conclusion is supported by other studies, where the normal thickness of oedematous epithelium has been shown by pachometry. The results in the present study further suggest that stromal oedema in the contact lens wearer is a result of a relative loss of endothelial function, leading to a swelling that moves in a posterior to anterior direction.

The impact of aging on neuronal morphology in the rat hypothalamo-neurohypophysial system: An immunohistochemical study

Tissue sections of the hypothalamus, median eminence and posterior pituitary gland from normal adult female rats, rats 12–24 months old, and rats more than 24 months old were examined by light microscopy after staining with the immunoperoxidase technique. Purified antisera raised against oxytocin and vasopressin, and an antiserum cross-reactive with the rat neurophysins were used to localize these antigens in the rat hypothalamo-neurohypophysial system (HNS). In all elements of the rat HNS, the staining intensity for the neurohypophysial hormones decreased progressively with age. Cells of the paraventricular nucleus (PVN) showed a greater depletion of immunoreactive material than those cells of the supraoptic nucleus. Oxytocin-containing neurons were more depleted than vasopressin-containing neurons. Morphological comparison of the neurons from the three groups of rats revealed cell types that were representative of secretory activity, as well as cells that were suggestive of stages leading to cellular destruction. There were cells that were highly activated whilst in the oldest rats studied many cells were severely vacuolated. Cells at the anterior extent of the PVN (that part of the PVN which contains exclusively oxytocin cells) were more affected by the degenerative affects of aging than the other magnocellular elements of the rat HNS. The morphological and degenerative changes in cells of the SON and PVN with age are consistent with previously reported physiological dysfunctions involving the hypothalamo-neurohypophysial axis.

Study of fibrous plaques occurring in the coronary arteries of children

The pathology of the coronary arteries of children, in relation to atherosclerotic involvement, appeared as a pathology of the main emergence areas and branching points of the left coronary artery and particularly of the anterior descending artery. The first atherosclerotic lesions occurred as non-raised fibrous plaques in 2% of children 6–10 years old and in 4% of children and juveniles 11–15 years old. In the latter age group fatty streaks and gelatinous plaques were also seen in 6% of the subjects; in their appearance they lag behind fibrous plaques by 5–8 years. Indirect evidence was obtained that some branch pads or cushions might be converted into fibrous plaques. The transitional aspects included edema, histolysis (elastolysis, collagenolysis, ground-substance depletion and degenerative cell changes), followed by reorganization and homogeneization of the pre-existing heterogeneous microarchitecture; in a final stage the prevalent processes seemed to be the nodular proliferation of smooth muscle cells and the abundant neoformation of collagen fibers. In essence the results show that in atherosclerosis the coronary arteries are involved in a different sequence and histogenetic pattern than the aorta.

Myocardial structure and function in patients with aortic valve disease and their relation to postoperative results

Left ventricular angiographic studies were performed before and 6 months after aortic valve replacement with a Björk-Shiley prosthesis in 21 patients, 5 with aortic stenosis, 8 with mixed aortic valve lesions and 8 with aortic insufficiency. The degree of myocardial fibrosis and myocardial ultrastructural changes were evaluated from transmural needle biopsy specimens obtained from the left ventricular anterior free wall at operation. Twelve patients without heart disease served as control subjects for angiographic data. Patients with aortic valve disease had a significantly higher left ventricular mass before operation than control subjects and a lower ejection fraction and mean normalized systolic ejection rate. After operation left ventricular mass decreased considerably but did not reach normal level. Ejection fraction and mean normalized systolic ejection rate became normal in all patients with aortic valve disease. The percent fibrosis determined with morphometry was significantly higher in the subendocardium than in the subepicardium of pressure-overloaded hearts (predominant stenosis) (19 versus 13 percent) but equal in both layers of volume-overloaded hearts (predominant regurgitation) (19 versus 18 percent). Electron microscopy revealed significant intracell alterations of the nucleus, sarcomeres, mitochondria and cytoplasmic reticulum. When all patients, regardless of type of aortic valve lesion, were considered, there was no significant correlation before operation between percent fibrosis and ejection fraction ( r 0.10) or mean normalized systolic ejection rate ( r 0.02) but a significant inverse relation between left ventricular mass and ejection fraction ( r 0.54) as well as mean normalized systolic ejection rate ( r 0.49). These data suggest that (1) Depressed left ventricular function in aortic valve disease is associated with ultrastructural degenerative cell changes, but complete recovery of cardiac function after aortic valve replacement is not prevented by these changes. (2) Interstitial myocardial fibrosis is not a primary determinant of depressed cardiac function in aortic valve disease.

Correlation of scanning electron microscope and light microscope findings in uninflamed and pathologically involved human pulps

The use of the scanning electron microscope has been investigated as a modality for pulpal diagnosis. Findings in ten normal, inflamed, and necrotic human pulps were correlated with light microscope findings. Inflammatory cell identification by SEM was found to be difficult. The inflammatory cells, especially lymphocytes, appeared in varying forms in SEM. Polymorphonuclear leukocytes and macrophages had similar surface structure. Degenerative changes of cells and fibers and dystrophic mineralizations were graphically depicted by SEM.

Sequential pathological changes in natural and experimental dermatophilosis in Bunaji cattle

Differences in histopathological changes between experimentally and naturally induced dermatophilosis were slight; natural infections persisted longer as they tended to be complicated by other concurrent dermatoses. Sequential pathological changes in bovine dermatophilosis included congestion, dermal oedema and neutrophilic infiltration of dermal papilae and epidermis by the third day; degenerative changes of cells in the upper portion of the stratum spinosum and invasion of the keratinised layer and hair follicles by the filamentous forms of Dermatophilus congolensis by the fourth day; regenerative processes involving the basal cells and selective cellular destruction in the spinous layer and further hair follicle invasion by D congolensis by the ninth day; and proliferative changes characterised by parakeratosis, hyperkeratosis, acanthosis and dermal sclerosis by the 15th day. It is postulated that cattle with hair follicles parasitised by D congolensis are carriers and are responsible for perpetuation of bovine dermatophilosis from one season to the next.

Advantages of the Short-Term Estrogen Test in Mailing Smear Diagnosis

In the diagnosis of Mailing Smears, we are often hampered by most inadequate information accompany ing the smears, by the many factors which induce degenerative cell changes in specimens, and by difficulties inherent in the patients themselves.Inadequate information concerning such things as estrogen deficiency and/or inflammatory changes is a real problem in smear diagnosis. Cell changes causing problems may be classed as degenerative, autolytic or atrophic.Papanicolaou first suggested the administration of estrogen to such patients in order to induce maturation of the normal squamous epithelium, and to reduce the above problems without affecting the cytomorpho-logy of possibly present malignant tumour cells.The authors' purpose in presenting this paper is to evaluate the Short-Term Estrogen Test in 33 women who exhibited degenerative, autolytic, atrophic and inflammatory cell changes in their mailing smears.The method of administration of the Estrogen Test is as follows:1. Oral administration of 3 mg of Estriol daily through 5 days.2.Intramuscular injection of 10 mg long acting Estrogenic substances.In order to evaluate the effectiveness of this test, the authors used 3 indexes, as follows:1. Maturation index.2. EI/KPI Pundel's Index.3. Coincidence of Papanicolaou's classification with histology.If, after estrogen administration, the smear exhibited a good response to all 3 indexes, its response was classed as good. If there was good response to two, the classification was fair, and if to only one, or even to none at all, the classification was poor.The results of this study are as follows: - ESTROGEN TESTS REQUESTED-33 CASES.Good response 20Fair response 5Poor response 5Follow-up failed 39 of the cases with good response had been classed as equivocal smears before this test, but afterwards were classed as having good response, and were clearly diagnosable as malignant smears.The authors therefore recommend this test as a help - ful and useful method of ruling out equivocal maliing smears to make a good diagnosis, and thus avoiding unnecessary biopsies.

Effect of constant temperature on survival rate, neurosecretion and endocrine cells, and digestive enzymes in Morimus funereus larvae (Cerambycidae: Coleoptera)

Abstract o 1. The effect of two constant temperature levels (12 and 23°C) on the larvae of Morimus funereus , previously maintained at 8°C during 30 days, has been studied. 2. This effect has been examined at three different levels: organism (survival), cell (neurosecretory cells of the protocerebrum and of the suboesophageal ganglion, as well as secretory cells of corpora allata) and enzyme (midgut amylase and protease). 3. At the temperatures examined accumulation of neurosecretory material in A 1 neurosecretory cells (the medial group of protocerebrum and ventromedial cells of suboesophageal ganglion) was observed as well as degenerative changes in cells of the corpora allata and a decrease in midgut amylolytic and proteolytic activities.

Ultrastructural effects of acute tetraethyllead poisoning on nerve cells of the rabbit brain

The ultrastructural effects on nerve cell components of selected brain areas (frontal cortex, cerebellum, hippocampus) were studied after exposure of rabbits to tetraethyllead (TEL). A single dose of 100 mg/kg of TEL leads, after a latency period of 12 to 18 hours, to neurological disorders such as convulsions, and produces significant lesions of components of pyramidal cells and astroglial cells. These develop before the onset of major neurological signs of toxic manifestation. In general two types of degenerative cell changes are identified: cellular pyknosis and cellular hydrops, each specific to certain cell layers of selected brain areas. The subcellular manifestation of nerve cells undergoing hydropic degeneration exhibit a distinct pattern. The following sequence of appearance of structural alterations was determined: (1) folding of the nuclear membrane, (2) swelling and severe lesions of mitochondria, (3) hypertrophy of Golgi complexes and (4) patchy chromatolysis of the ergastoplasm. Progressive hypertrophy of Golgi saccules and vacuolization of ergastoplasm areas lead to a vacuolar hydropic degeneration of affected nerve cells. The cytopathogenesis is discussed in regard to recent findings concerning the subcellular mechanism of tetraethyllead intoxication.

Investigation about the Necrosis Formation “Sharilka” (Aladja) on the Leaves of Field-Grown Tobacco Plants: Part I. About the Causes of the Phenomenon Part II. BiochemicaI Changes in the “Sharilka”-Affected Leaf

AbstractA specific dot-like necrosis formation on Oriental type tobacco, called "sharilka'' was studied. The phenomenon is of a physiological nature. It manifests itself under conditions of water excess during the time when the leaves begin to become overripe. It was established that susceptibility to "sharilka" is connected with a low content of pectins and proteins. The latter fact predetermines the lower water binding capacity of protoplasm or higher content of free water in the tissues which suffer from "sharilka''. The raised quantity of free water as a possible source of degenerative cell changes, which become apparent on the leaf in the form of "sharilka", was considered