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Biomedical subjects

E Horvath

Publications and source records attributed to E Horvath.

At least 253 records · Page 14Linked to original sources
PubMed1976

Intracisternal virus-like particles in a human pituitary adenoma.

Electron microscopy revealed the presence of intracisternal virus-like particles in a mixed pituitary adenoma consisting of growth hormone cells and prolactin cells. The tumor was removed by surgery from a 48 year old man with a multiple endocrine adenomatosis type I syndrome. The significance of virus-like particles in the pathogenesis of pituitary adenomas remains to be elucidated.

Adenoma↗
PubMed1976

A new look at pituitary adenomas: structure elucidating function.

Cases of seven different types of surgically resected pituitary adenoma are described. Included are tumours secreting prolactin or growth hormone or both, and nonfunctioning tumours--undifferentiated and oncocytic tumours, and one tumour with cells of the adrenocorticotropin-melanocyte-stimulating hormone type. The final interpretation of a case of pituitary adenoma should include an assessment of thorough morphologic studies, using not only routine staining and light microscopy but also immunostaining and electron microscopy, to complement the biochemical, radiologic and clinical evaluation.

Acromegaly↗
PubMed1976

Pigmented adenoma of adrenal cortex associated with Cushing's syndrome: light and electron microscopic study.

A pigmented adenoma of the adrenal cortex was surgically removed from a thirty-nine-year-old woman with clinical and biochemical manifestations of Cushing's syndrome. Light and electron microscopic study revealed numerous pigment granules, exhibiting the structural features of lipofuscin in the cytoplasm of the adenoma cells. It appears that adrenocortical adenomas with excessive pigment deposition can be accompanied by increased production of corticosteroid hormones.

Adenoma↗
PubMed1976

Ultrastructural classification of pituitary adenomas.

Forty-eight surgically removed pituitary adenomas have been investigated by electron microscopy. Distinct differences in fine structural appearances permitted their separation into 5 classes: 1) Growth hormone, (GH)-cell tumors; 2) Prolactin cell tumors; 3) Mixed adenomas composed of GH and prolactin cells; 4) Adrenocorticotrophic-Melanocyte stimulating hormone (ACTH-MSH) cell tumors; 5) Undifferentiated cell adenomas. Densely and sparsely granulated tumors were distinguished within classes 1, 2 and 4. Although these two forms appeared to represent well defined entities, they may be variants of the same tumor differing only in pace of hormone production and/or release. Number and size of secretory granules varied considerably among tumors composed of the same cell type indicating that pituitary tumor classification cannot be based solely on granule morphology. This classification takes into account morphogenesis with emphasis on clinical features and structure-function relationship.

Adenoma, Acidophil↗
PubMed1976

Light and electron microscopic features of a pituitary adenoma in Nelson's syndrome.

Electron microscopy of an amphophil pituitary adenoma surgically removed from a 51-year-old woman who had Nelson's syndrome revealed that the tumor was composed of melanocorticotroph cells. This finding is consistent with the view that in the human pituitary gland one single cell type produces both adrenocorticotropic hormone (ACTH) and melanocyte-stimulating hormone (MSH). In contrast to the ultrastructure of pituitary adenomas associated with Cushing's syndrome, no or only very few microfilaments were detected in the cytoplasm of the tumor cells, suggesting that adrenocortical steroids are required for the formation of microfilaments. The presence or absence of microfilaments in the tumor cells may be regarded as a distinguishing ultrastructural feature between Cushing's syndrome and Nelson's syndrome. It appears that changes in the level of circulating corticoids may affect the ultrastructural features of melanocorticotroph cells not only in normal pituitaries but also in adenohypophyseal adenomas.

Adenoma↗
PubMed1976

Effect of starvation on pituitary growth hormone cells and blood growth hormone and prolactin levels in the rat.

Growth hormone (GH) cells of rats were studied on days, 2, 4 and 7 of starvation. Immunoperoxidase staining for light microscopy confirmed the presence of GH in the pituitaries of all groups of animals. Electron microscopy revealed crinophagy in the cytoplasm of GH cells on days 4 and 7. By ultrastructural morphometry, volume density and the diameter of secretory granules in the cytoplasm of GH cells remained unchanged. Blood GH determinations showed a significant decrease on day 4 of the starvation period. On day 7 most of the values were in the range of the controls. Blood prolactin levels fell significantly on day 7. It appears that the pituitary is capable of secreting GH even in rats completely deprived of exogenous nutrients.

Animals↗
PubMed1976

Human mixed somatotrophic and lactotrophic pituitary adenomas.

Six patients with acromegaly at examination were found to have pituitary adenomas composed of cells that secreted GH and PRL. This was demonstrated by the elevated serum hormone concentrations, by immunoperoxidase staining of 5 specimens, and by electron microscopic examination of 4. Ultrastructural characteristics, described in detail, suggest that these adenomas were mixed adenomas consisting of 2 well-defined, distinct cell types, each secreting one hormone. By immunoperoxidase staining some cells were found to contain immunoreactive growth hormone, other cells immunoreactive prolactin. No cells were detected exhibiting immunostaining for both growth hormone and prolactin. Eelctron microscopy, consistent with the results of immunostaining, revealed the presence of two distinct cell types, distinguishable from each other by their characteristic fine structural features. No intermediate forms were noted. Thus there was no evidence to suggest that one cell type might transform to the other. Present findings seem to indicate that mixed adenomas secreting growth hormone as well as prolactin and consisting of somatotrophs as well as lactotrophs do occur in the human pituitary gland. Although all the results obtained so far suggest that these tumors are composed of two distinct cell types and thus can be interpreted as representing real mixed adenomas, further work is required to establish whether or not they derive from one common progenitor.

Acromegaly↗
PubMed1976

Lysosomal disposal of secretory granules and their transformation into pigment particles in spontaneous prolactin cell adenomas of the rat pituitary.

Light and electron microscopic study of spontaneous prolactin cell adenomas, found at autopsy of 26 aging female Long-Evans rats and of 9 aging male Wistar rats, revealed pigment particles in the cytoplasm of some adenoma cells. It is postulated that most of the pigment particles derive from secretory granules. The presence of crinophagy and autophagy are interpreted as the morphologic expressions of lysosomal activation. The causative mechanisms accounting for lysosomal disposal of secretory granules and their transformation to pigment particles remain to be elucidated.

Adenoma, Chromophobe↗
PubMed1976

Centrioles and cilia in non-tumourous anterior lobes and adenomas of the human pituitary.

Electron microscopy revealed the presence of centrioles and cilia in non-tumourous adenohypophysiocytes as well as in various adenomas of the human pituitary gland. Accumulation of centrioles and cilia was evident in sparsely granulated growth hormone cell adenomas. Abundance of centrioles is a valuable sign in establishing the diagnosis of this tumour. The possible functional significance of centrioles and cilia in adenohypophysial cells has been discussed.

Adenoma↗
PubMed1975

Ultrastructure of two cases of anaplastic giant cell tumor of the human thyroid gland.

Electron microscopy of two cases of anaplastic giant cell tumor of the thyroid revealed that these neoplasms consisted of pleomorphic cells with large, bizarre-shaped nuclei and relatively little cytoplasm rich in rough endoplasmic reticulum. The presence of various intercellular junctions, the resemblance of tumor cells to non-neoplastic epithelial cells of the thyroid follicles and the observation that follicular remnants were identified in the tumor, support the assumption that these tumors derive from the follicular epithelium and can be regarded as carcinomas. Aggregates of cytoplasmic spherical bodies, ultrastructurally similar to virus particles, were detected in some tumor cells. Further investigation is required to determine the nature of these structures and establish their pathogenetic role. In some tumor cells, tubuloreticular arrays were noted within the dilated cisternae of the endoplasmic reticulum; these may represent ultrastructural manifestations of nonspecific injury.

Aged↗
PubMed1975

Pituitary chromophobe adenomas consisting of prolactin cells: a histologic, immunocytological and electron microscopic study.

Morphologic studies of pituitary neoplasms removed by srugery from 36 human patients revealed 8 chromophobe adenomas which differed clearly from the remaining tumors. The cytoplasm of the adenoma cells failed to stain with PAS, aniline blue, adehyde fuchsin, aldehyde thionin, orange G or light green, but positively stained granules were found by using erythrosine or carmosine. Immunoperoxidase technique disclosed the presence of prolactin in the cytoplasm of some adenoma cells. The adenoma cells exhibited distinct ultrastructural features such as well developed rough surfaced endoplasmic reticulum with Nebenkern formation, prominence of Golgi apparatus, presence of misplaced exocytosis as well as pleomorphism of secretory granules with a considerable variation of size ranging from 130 to 500 nm in diameter. Thus, by electron nicroscopy the adenoma cells showed a close resemblance to prolactin cells of the non-tumouous pituitary glands except for the reduced size and number of secretory granules. Thes chromophobe adenomas are regarded as representing a distinct pathological entity clearly distinguishable from other forms of pituitary neoplasms. In view of the morphologic findings and the elevation of blood prolactin level (measured in 3 patients) the term, "sparsely granulated prolactin producing pituitary adenoma", appears to be the most appropriate one to designate these tumors.

Adenoma, Chromophobe↗
PubMed1975

Pituitary melanocorticotrophinoma with amyloid deposition.

The light and electron microscopic features of a pituitary adenoma composed of adrenocorticotrophic hormone (ACTH) and melanocyte stimulating hormone (MSH) cells with perivascular amyloid deposition is reported. Histochemical and fine structural data indicate that this material is APUDamyloid and is present in the extra-cellular perivascular spaces. It is suggested that the differences in fine structure and of distribution of the amyloid in pituitary adenomas is dependent upon the cell of origin.

Adenoma↗
PubMed1975

Annulate lamellae in adenomas of human pituitary glands.

Twelve nontumorous adenohypophyses and 36 various pituitary adenomas, removed by surgery, have been investigated by electron microscopy in order to shed some light on annulate lamellae, primarily on their ultrastructural features, incidence, origin, fate and functional significance. No annulate lamellae were found in the nontumorous adenohypophyses and in 33 pituitary adenomas. They were, however, detected in two adenomas consisting of undifferentiated cells and one adenoma composed of sparsely granulated prolactin cells indicating that these unique membrane configurations cannot be regarded as an exceedingly rare finding and, furthermore, that they may be disclosed not only in undifferentiated but occasionally in highly differentiated cells. Annulate lamellae may arise from endoplasmic reticulum and/or nuclear envelope and consist of arrays of smooth walled double membrane sheets exhibiting regularly spaced interruptions as well as continuities with the endoplasmic reticulum. No relationship was established between annulate lamellae and adenohypophysial secretory activity. Our findings seem to be consistent with the view that annulate lamellae are present in those cells which have the tendency to proliferate.

Adenoma↗