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  • 1
    Electronic Resource
    Electronic Resource
    Hypothalamic neuronal hamartoma associated with pituitary growth hormone cell adenoma and acromegaly (1980)
    Springer
    Acta neuropathologica 52 (1980), S. 231-234 
    Details
    ISSN: 1432-0533
    Keywords: Acromegaly ; Growth hormone cell adenoma ; Hypothalamic neuronal hamartoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A hypothalamic neuronal hamartoma associated with a sparsely granulated growth hormone cell adenoma of the pituitary and acromegaly is reported. It is suggested that the patient had a primary neuronal tumor, whose neurosecretory activity promoted the development of the growth hormone secreting pituitary adenoma causing acromegaly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705811
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  • 2
    Electronic Resource
    Electronic Resource
    Oncocytomas and null cell adenomas of the human pituitary: Morphometric and in vitro functional comparison (1988)
    Springer
    Virchows Archiv 413 (1988), S. 333-339 
    Details
    ISSN: 1432-2307
    Keywords: Electron microscopy ; Morphometry ; Null cell adenoma ; Oncocytoma ; Pituitary adenoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this study, light microscopic and ultrastructural morphometric features of oncocytomas and null cell adenomas were compared and the morphometric data were correlated with in vitro endocrine activity. All tumours were unassociated with clinical or biochemical evidence of hormone excess and were diagnosed as oncocytomas or null cell adenomas, using histology, immunohistochemistry and electron microscopy. In oncocytomas, when compared with null cell adenomas, light microscopic morphometry revealed that total cell areas were significantly larger and nuclear cytoplasmic ratios were smaller due to an increase in cytoplasmic areas. Ultrastructural morphometry disclosed an abundance of mitochondria in oncocytomas. Absolute volumes of cytoplasmic organelles per cell were not reduced in oncocytomas compared with those of null cell adenomas. These results indicate that accumulating mitochondria do not replace other cytoplasmic organelles, and furthermore that the functional potential of oncocytomas is not lost. In vitro study demonstrated the production of pituitary hormones, primarily gonadotropins in oncocytomas and null cell adenomas. It can be concluded that oncocytomas, which represent the final stage of oncocytic transformation, have a close relationship with null cell adenomas based on morphometric comparison as well as in vitro studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00783026
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  • 3
    Electronic Resource
    Electronic Resource
    The pars tuberalis of the human pituitary (1982)
    Springer
    Virchows Archiv 399 (1982), S. 49-59 
    Details
    ISSN: 1432-2307
    Keywords: Pituitary ; Pars tuberalis ; Gonadotrophs ; Squamous nests ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Forty autopsy pituitaries were studied to elucidate the histology, immunocytology and ultrastructure of pars tuberalis in subjects with normal and abnormal endocrine homeostasis. Pars tuberalis consisted mainly of gonadotrophs interspersed with few corticotrophs and thyrotrophs, histologically resembling those of pars distalis. Somatotrophs and lactotrophs were not identified. There were no histologic differences attributable to age or sex. In cases of glucocorticoid excess, pars tuberalis corticotrophs showed Crooke's hyalinization. Following castration or hypophysectomy, pars tuberalis gonadotrophs exhibited more intense immunostaining for FSH1 and LH than did normals. Ultrastructural analysis revealed gonadotrophs and corticotrophs showing no evidence of active secretion; immunoelectron microscopy demonstrated FSH, LH and ACTH in secretory granules. By light microscopy, squamous nests, often identified in pars tuberalis, were positive for immunoreactive keratin; cells at their periphery contained FSH, LH or ACTH, indicating derivation of nests by squamous metaplasia from gonadotrophs and corticotrophs. By electron microscopy, clusters of epithelial cells containing desmosomes and tonofilaments were surrounded by granulated gonadotrophs. Human pars tuberalis cells represent mainly a subpopulation of gonadotrophs possessing all organelles required for synthesis and storage of hormones but showing ultrastructural features of functional inactivity; the reasons for this inactivity and for the formation of squamous nests remain unexplained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00666218
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  • 4
    Electronic Resource
    Electronic Resource
    Immunoreactive luteinizing hormone in functioning corticotroph adenomas of the pituitary (1990)
    Springer
    Virchows Archiv 417 (1990), S. 361-367 
    Details
    ISSN: 1432-2307
    Keywords: Corticotroph adenoma ; Adrenocorticotropin ; Luteinizing hormone ; Immunohistochemistry ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two pituitary adenomas removed from a 37-year-old woman and a 26-year-old woman with typical Cushing's disease were studied by light and electron microscopy, immunohistochemistry and radioimmunoassay of tissue culture media. Both patients had high plasma levels of cortisol and normal levels of luteinizing hormone (LH). Both tumours were monomorphous, composed of densely granulated corticotrophs; the tumour cells contained periodic acid-Schiff positivity, were arranged in a sinusoidal pattern and, ultrastructurally, contained well-developed cytoplasmic organelles. By immunohistochemistry the majority of tumour cells contained immunoreactive adrenocorticotropin (ACTH); approximately 10% of the tumour cell population contained LH immunoreactivity. The LH-positive cells tended to form clusters scattered widely throughout the tumour tissues. LH immunoreactivity was demonstrated in some ACTH-immunoreactive cells on serial sections. Large amounts of immunoreactive ACTH and smaller quantities of LH, follicle stimulating hormone and αsubunit were released into the culture media and release of the glycoprotein hormones responded in parallel to corticotropin releasing hormone stimulation or inhibition by cortisol. These findings indicate that LH can be simultaneously produced and released by ACTH-producing tumour cells of otherwise typical functioning corticotroph adenomas. The capacity for LH production may be acquired during neoplastic proliferation. This is the first detailed report of concurrent production of LH by pituitary corticotroph adenomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605790
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular Determinants of Pituitary Cytodifferentiation (1999)
    Springer
    Pituitary 1 (1999), S. 159-168 
    Details
    ISSN: 1573-7403
    Keywords: pituitary ; tumors ; cytodifferentiation ; transcription factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pituitary is a complex gland and is composed of several cell types, each responsible for the production of specific hormones. In the past, it was thought that one cell could make only one hormone; the concept of plurihormonality was poorly understood. Plurihormonal adenomas were thought to be either composed of multiple cell types, each producing one hormone (plurimorphous adenomas) or composed of poorly differentiated cells that exhibited abnormal production of multiple hormones. However, the molecular factors that determine hormone production have now been identified as transcription factors that target specific hormone genes. These factors have clarified three main pathways of cell differentiation. ACTH- producing corticotrophs are determined by corticotropin upstream transcription-binding element (CUTE) proteins including neuroD1/beta2. Bihormonal gonadotrophs require expression of steroidgenic. factor (SF)-1. The complex family of Pit-1 expressing cells can mature into somatotrophs, mammosomatotrophs, lactotrophs or thyrotrophs with the additional expression of estrogen receptor (ER)α, which enhances PRL secretion, or thyrotroph embryonic factor (TEF) which stimulates TSH-beta production. The recognition of these molecular determinants of adenohypophysial cytodifferentiation has clarified the patterns of plurihormonality which have been recognized in pituitary adenomas and provide a framework for classification of these tumors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009948813587
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  • 6
    Electronic Resource
    Electronic Resource
    Utilization of electron microscopic techniques in the in vitro study of adenohypophysial function and regulation (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 20 (1992), S. 136-151 
    Details
    ISSN: 1059-910X
    Keywords: Pituitary ; Adenomas ; Tissue culture ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Morphologic studies of human adenohypophysial cells using immunocytochemistry and electron microscopy have characterized the hormone-producing cell types of the normal gland and pituitary adenomas. The classifications which have emerged allow more accurate clinicopathologic correlations than ever before, but have also raised new questions concerning cytogenesis, pathogenesis, and structure-function correlations. We report the results of studies which marry the conventional morphologic techniques of light microscopy, immunohistochemistry, electron microscopy, and ultrastructural immunocytology with functional analyses using tissue culture and radioimmunoassay of hormones released into culture media. The hormone secretory activity of nontumorous and adenomatous pituitary cells is correlated with their structural features; their secretory responses to several adenohypophysiotropic factors are compared with morphologic alterations which are characterized at the light and electron microscopic levels by morphometric analysis. These studies have shown that hypothalamic stimulating hormones increase hormone release by their target cells and alter the ultrastructural appearance of the affected cells by increasing organelles involved in hormone synthesis. Inhibitory drugs and adrenal and gonadal steroids are capable of suppressing hormone release by some tumors and also give rise to morphologic changes which correlate with the functional inhibition. Hormone release by clinically nonfunctioning adenomas has been characterized and the behavior of these tumor cells in vitro sheds some light on the reasons for lack of clinical symptomatology. The plurihormonal nature of several nontumorous and adenomatous pituitary cell types has been characterized in vitro. The results of these studies provide the basis for more accurate structure-function correlations which can be used to study the hormonal milieu in vivo, to predict the role of pathogenetic factors in pituitary tumorigenesis, and to assess the therapeutic value of stimulating or inhibiting hormones and drugs.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070200203
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