1,721,152 research outputs found
Ultrastructure of human parathyroid cells in health and disease
No full textParathyroid glands (n = 271) removed from 130 patients were examined by light and electron microscopy. A standardized method of tissue processing was employed and morphometry was performed. The aim of the paper is to provide a description of the human parathyroid chief cell ultrastructure in health and disease, with quantitative evaluation of structures involved in secretion of parathyroid hormone in a large case series, and to discuss their role in current diagnostic histopathology. The patients were euparathyroid (n = 10), or affected by primary (n = 97), secondary (n = 8), or tertiary (n = 15) hyperparathyroidism. In normal glands, solid parenchyma was composed of chief cells, large clear cells, transitional-oxyphil cells, and oxyphil cells. Chief cell hyperplasia, pseudo-adenomatous hyperplasia, adenoma, water-clear cell hyperplasia, and carcinoma were the most usual forms of parathyroid disease responsible for primary hyperparathyroidism. In chief cell hyperplasia, all the parathyroid glands were enlarged and the chief cells were in an active state of hormone secretion, with a large Golgi complex, abundant rough endoplasmic reticulum (RER), small lipid droplets, and tortuous plasma membrane. In pseudo-adenomatous hyperplasia, one gland was enlarged and the others displayed a normal size; however, electron microscopic examination and morphometric analysis showed that all the glands had active cells. Adenomas displayed a pattern similar to those of pseudo-adenomatous hyperplasia, with one gland enlarged and the others of normal size. However, ultrastructural examination and morphometry showed that the normal-size glands were hypo-active. Water-clear cell hyperplasia showed cells filled with cytoplasmic vacuoles. In these cells, structures with intermediate features between secretory granules and vacuoles were visible. Nucleo-cytoplasmic atypias were frequently visible in parathyroid carcinoma cells. In secondary and tertiary hyperplasia, active chief cells were regularly mixed with oxyphil or transitional-oxyphil cells. The tertiary hyperplasia was characterized by RER-associated structures that were not found in the normal or other pathological conditions. These results demonstrate that electron microscopy and morphometry represent useful tools in parathyroid histopathology
In vivo MRI in different models of experimental epilepsy.
No full textIn order to investigate epilepsy, that is one of the most common neurological disorders, in the last decades different animal models have been proposed. Prevention, diagnosis, treatment and basic knowledge have been improved by the mean of these models.
Numerous animal models have been developed in epilepsy research, both for generalized and for simple / complex partial seizures. Animal models for generalized seizures include sensory (light, noise, movement, etc) or electrical stimulations and genetic models. Models for focal seizures include topical or systemic application of pro-convulsive compounds or electrical stimulation. Baboons, mice, rats, rabbits, and Fayoumi chicken have been extensively used in this regard.
Since 1983, when magnetic resonance spectroscopy was used to evaluate for the first time in vivo alterations induced by status epilepticus in rabbit, an increasing interest for the neuroimaging perspective has led to new insights in the study of epileptic disorders. In the early 1990s experimental studies provided evidence for the feasibility of magnetic resonance imaging analysis and detection of tissue damage in kainic acid-induced epilepsy in rat. In the following years a wealth of data has been obtained by the mean of functional MRI and / or by diffusion-weighted images.
The studies reported in the literature of the last decades indicate in vivo magnetic resonance of epilepsy model as valuable and extremely informative tool
Ultrastructure of brown adipocytes mitochondria in cell culture from explants
No full textBrown adipocytes lose in culture their typical mitochondria, which are replaced by others of non typical morphology. During studies aimed at clarifying this phenomenon we found that better preservation of the 'typical' mitochondrial morphology is obtained in vitro after a long period of time, when cells from small fragments (explants) of brown adipose tissue (BAT) are cultured instead of collagenase-isolated brown adipocytes. These results suggest that the explant technique could be better suited to study brown adipocytes in culture than other methods employing collagenase-isolated cells
Ultrastructural changes in the mammry gland of the lactating rat induced by the treatment with bromocriptine
No full textMorfologia ultrastrutturale delle cellule follicolo- stellate dell'adenoipofisi di ratto durante l'inibizione della lattazione
No full textThe vomeronasal organ in the frog, Rana esculenta. An electron microscopy study
No full textThe ultrastructure of the vomeronasal organ (Jacobson's VNO) of the frog, Rana esculenta, was studied under the transmission and scanning electron microscope. Four cell types were identified: ciliated, bipolar, glial-like, and basal. Ciliated cells are unique to the frog VNO and show morphological evidence of secretion; bipolar (neuronal) cells are arranged in columns and reach the free surface of the epithelium with knobs bearing microvilli. The latter are in contact with amorphous material not described previously. Glial-like cells wrap bipolar cells in the epithelium and poorly differentiated basal cells are found just over the basal lamina. The vascular pump described in mammal VNO is not present at all in the frog VNO. We conclude that in the frog the VNO is closer to the reptilian than the mammalian VNO, although the frog VNO shows some unique morphological characteristics
An ultrastructural immunocytochemical study of secretori granules of adenohypophyseal tumor
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