Oncocytomas and null cell adenomas of the human pituitary: Morphometric and in vitro functional comparison

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.     

In vitro studies of human pituitary adenomas

The application of morphologic and tissue culture techniques to the study of human pituitary adenomas allows further investigation of structure-function correlations. Using these methods, we have documented morphometric differences between densely and sparsely granulated somatotroph adenomas but the release of growth hormone in vitro and responses to adenohypophysial hormones/drugs do not correlate with tumor type. The morphologic and functional alterations in somatotroph adenomas exposed to SMS 201-995 appear to be reversible in vitro. Incubation of lactotroph adenomas with bromocriptine for 3 days directly reduces tumor cell size, cytoplasmic volume and cytoplasmic volume densities of endoplasmic reticulum and Golgi regions; these changes are similar to the effects of longterm bromocriptine therapy in vivo. Tissue culture studies of gonadotroph adenomas of men confirm that gonadotropin-releasing hormone (GnRH) stimulates gonadotropin release by tumor cells and yields morphologic evidence of increased hormone synthesis whereas these tumors have variable sensitivity to gonadal steroids; structural changes in tumor cells correlate with hormone release after stimulation, suggesting that morphologic parameters may reflect the hormonal milieu of these adenomas. Null cell adenomas and oncocytomas release small quantities of glycoprotein hormones, predominantly gonadotropins in vitro and there are no functional differences between these 2 tumor types; gonadotropin release responds to GnRH stimulation and, paradoxically, to other adenohypophysiotropic hormones, but such stimulation does not result in secretion of other adenohypophysial hormones by these tumors.     

Structure-function correlations of human pituitary gonadotroph adenomas in vitro

Two pituitary gonadotroph adenomas were studied in vitro to characterize structure-function correlations. Both tumors were from men, aged 63 and 69 years, who had elevated blood levels of follicle-stimulating hormone (FSH) and normal blood luteinizing hormone (LH) and testosterone values. The surgically resected adenomas contained diffuse immunohistochemical positivity for beta-FSH, beta-LH, and alpha-subunit of glycoprotein hormones; by electron microscopy they were composed of well-differentiated gonadotrophs. In vitro, both tumors released FSH, LH, and alpha-subunit. Morphometric studies were performed on surgically resected and cultured adenoma cells. Compared with the surgical specimens, the cultured cells had decreased cytoplasmic volume densities of endoplasmic reticulum and Golgi apparatus and slightly increased cytoplasmic volume densities of secretory granules. Incubation with gonadotropin-releasing hormone (GnRH) for 2 and 24 hours increased FSH, LH, and alpha-subunit release by both tumors; morphometry after 2 consecutive days of exposure confirmed significant increases in cytoplasmic volume densities of endoplasmic reticulum and Golgi regions and marked decreases in that of secretory granules. There was no significant change in cell size, nuclear/cytoplasmic ratio, or secretory granule diameter. The two tumors differed in their response to gonadal steroids. Estradiol, testosterone, and progesterone stimulated release of FSH, LH, and alpha-subunit by one tumor and the morphologic changes paralleled the biochemical response; addition of testosterone suppressed the secretory and morphologic response to GnRH. The other tumor showed no significant response to estradiol or testosterone and addition of these steroids did not alter the response to GnRH. The results are consistent with the interpretation that GnRH stimulates not only release but also synthesis of gonadotropins by gonadotroph adenomas of men. The data also indicate variable sensitivity of these tumors to gonadal steroids with paradoxical stimulation alone and inhibition of response to GnRH. The structural changes correlate with the hormone release response in vitro.     

Silent somatotroph adenomas of the human pituitary. A morphologic study of three cases including immunocytochemistry, electron microscopy, in vitro examination, and in situ hybridization.

Pituitary adenomas, removed surgically from three women with normal or slightly elevated serum growth hormone levels and no evidence of acromegaly, were studied. The tumor cells were shown by electron microscopy to correspond to sparsely granulated somatotrophs but immunocytochemistry showed that they contained no, moderate, or little growth hormone. Two tumors examined in vitro secreted small amounts of growth hormone in the tissue culture medium initially with a spontaneous rise after several days, and responded to growth hormone-releasing hormone stimulation with increased growth hormone release. In situ hybridization demonstrated growth hormone mRNA expression in adenoma cells. Clinically silent somatotroph adenomas represent a hitherto undescribed entity; electron microscopy shows that they consist of somatotrophs, and express growth hormone mRNA but do not secrete growth hormone in amounts needed to raise substantially serum growth hormone levels and cause acromegaly. Further work is required to clarify the mechanisms accounting for the lack of clinical and biochemical evidence of hormone excess associated with these tumors.     

垂体ACTH细胞腺瘤的免疫电镜研究

5 cases of pituitary adenomas associated with Cushing's disease or Nelson's syndrome were studied with electron microscopy and immunoelectron microscopy by using protein A--gold complex. Diversified ultrastructure was displayed in these tumors, among which 4 revealed presence of ACTH positive secretory granules. These granules were round or polyhedric in shape, varied in number, size and electronic density. Bundles of microfilaments could be seen in the tumor cells frequently, which were of the highest diagnostic value. There was no significant difference found in ultrastructure and immunocytochemical reaction of adenomas in Cushing's disease and Nelson's syndrome.     

Vasoactive intestinal peptide in the human pituitary gland and adenomas. An immunocytochemical study

Recent evidence indicates that vasoactive intestinal peptide (VIP) may be involved in normal pituitary function. Immunocytochemistry was used to localize VIP in human biopsied pituitary adenomas and postmortem anterior pituitary glands. Paraffin sections were immunostained for VIP with the avidin-biotin-peroxidase technique. Strong VIP-like immunoreactivity (VIP-LI) was observed in 16 of 17 prolactinomas, 12 of 14 growth hormone-secreting tumors associated with acromegaly, four of 12 ACTH-secreting tumors, and 14 of 18 nonfunctioning pituitary adenomas. In most cases, VIP was colocalized with the classical pituitary hormones. Six of the 18 nonfunctioning tumors had no demonstrable hormone immunoreactivity; five of these stained strongly for VIP, whereas one was negative. Of 18 normal anterior pituitaries, 12 showed strong diffuse staining for VIP throughout the gland. One pituitary with VIP-LI came from an individual who had undergone pituitary stalk transection. Double-immunoenzyme labeling and immunoelectron microscopy demonstrated VIP-LI in many lactotrophs, scattered thyrotrophs, corticotrophs, and in an occasional gonadotroph. These results suggest the following: 1) VIP is present in more than one cell type in normal and adenomatous human pituitaries; and 2) VIP may be involved in the function and development of pituitary tumors.     

Morphological and functional characteristics of human pituitary lactotrophic adenomas in cell cultures

Some features of the morphological cellular structure of prolactin secreting human pituitary adenomas and their secretion of prolactin and somatotropic hormone in primary suspension cultures were investigated. A possiblein vitro proliferation of lactotrophs was established. The inhibitory effect of somatostatin and its synthetic analog sandostatin, on prolactin secretion in prolactinomas was found to be less than in somatotropic hormone-secreting pituitary tumors. Presented by A. N. Konovalov, Member of the Russian Academy of Medical Sciences Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 11, pp. 543–546, November, 1994     

正常人腺垂体和垂体腺瘤中滤泡星状细胞的免疫组织化学研究

Significance of the appearance of folliculo-stellate cells (FSC) was studied in 59 human adenohypophyses and 58 pituitary adenomas after being stained with anti-S100 protein and 6 anti-pituitary hormone antibodies. S100 protein positive cells, stellate in shape with expending cytoplasmic processes among endocrine cells (EC) appeared in all the human adenohypophyses and had a tendency to be clustered in small groups characterized by gathering of 3 to 5 cells in the alveoli. Age or sex difference seemed to have no influence on the distributive density of FSC. FSC in the pituitary adenomas may be derived from two origins. One was the residue of normal pituitary tissue left in adenomas, and the other one seemed to be the chief component of the tumor, known as folliculo-stellate cell adenoma.     

Incidental adenomas of the human pituitary gland

Using conventional histological technique, we investigated 44 adenomas (31 men, 13 women) incidentally found in 36 pituitaries (25 men, 11 women) obtained from 1,117 unselected autopsies. The overall incidence of adenomas was 3.2% (men, 3.8%; women, 2.4%) without any significant sex predominance. Size, age distribution, and histological appearances of these adenomas were similar to those previously reported by others. Statistical analysis showed that the adenomas had a predilection for occurrence at the anterior margin of the gland. We further investigated 33 available adenomas with immunohistochemistry using antibodies for various adenohypophyseal hormones, S-100 protein, and glial fibrillary acidic protein, of which 6 contained growth hormone, 3 contained growth hormone and prolactin, 7 contained prolactin, 6 contained follicle-stimulating hormone, 3 contained follicle-stimulating and luteinizing hormones, 2 contained thyroid-stimulating and adrenocorticotrophic hormones (separately), and 6 contained no adenohypophyseal hormones. None of adenomas revealed neoplastic proliferation of folliculostellate cells. To investigate tumor proliferation, nucleolar organizer regions were studied in 9 adenomas using the argyrophil method. The mean number per nucleus was slightly higher than that of corresponding, nontumorous adenohypophysis at a statistically significant level. No adenoma caused symptoms of adenohypophyseal hormone abnormalities.     

Null cell adenomas of the pituitary gland. An immunohistochemical study

Fourteen null cell adenomas of the pituitary gland were examined immunohistochemically with antisera against three general neuroendocrine markers and 22 hormones. All cases showed positive immunostaining for neuron-specific enolase, ten cases for synaptophysin, and six cases expressed chromogranin immunoreactivity. Hormone immunoreactivity was detected in a few cells in ten of the 14 cases studied and the number of hormones demonstrated in each case was one or two. Thyroid-stimulating hormone was detected in five of the 14 cases, gastrin in four, beta-endorphin in two, calcitonin gene related peptide in one, prolactin in one, and follicle-stimulating hormone in one.     

The TSH secretion in the human pituitary adenomas

TSH secretion by a pituitary tumor is very rare (2%) and it is often associated with another hormone: GH or PRL essentially. We present here nine tumors in which the TSH secretion was proved by immunocytochemistry (ICC) and by RIA in the tumor extracts, in the serum and in the culture medium. Four tumors secreted TSH only. Five tumors secreted TSH and GH predominantly. In 3 of them traces of other hormones (PRL and FSH) were also detected. The "pure" TSH adenomas were monomorphous with typical ultrastructural and immunocytochemical features. Plurihormonal TSH adenomas were bimorphous with different cells secreting GH and TSH or monomorphous with one type of cell which secreted TSH or GH or both TSH and GH. In a majority of the cases, the tumoral TSH secretion induced hyperthyroidism but in 2 patients with TSH adenoma there was euthyroidism and in another with TSH-GH adenoma there was no sign of acromegaly and GH serum levels were normal.     

垂体生长激素腺瘤对生长抑素类似物的耐药机制研究进展

生长抑素类似物能抑制垂体生长激素细胞对生长激素的分泌及相关肿瘤细胞的增殖,是目前垂体生长激素腺瘤临床治疗的首选药物.但部分患者因耐药而影响疗效,其耐药机制涉及生长抑素受体、受体下游信号传导通路、组织病理和细胞黏附分子等因素.     

Null cell adenomas,oncocytomas, and gonadotroph adenomas of the human pituitary: An immunocytochemical and ultrastructural anafysis of 300 cases

The immunocytochemical profile of 300 clinically nonsecreting pituitary adenomas was investigated. All tumors were diagnosed, classified, and separated into null cell adenomas, oncocytomas, and gonadotroph adenomas according to their ultrastructural morphology. The immunocytochemical analysis was based on the semiquantitative proportional estimates of positive cells immunostained for all known peptide and glycoprotein pituitary hormones including alpha-subunit. The majority of tumors (87%) were to some extent immunopositive for various hormones. Glycoprotein hormones were most frequently encountered. Usually, particularly in males, more than one subunit was present in the same tumor. In 97 tumors (32%) more than 25% of adenoma cells were immunoreactive for gfycoprotein hormones. Fifty-five tumors (18%) contained occasional cells immunopositive for growth hormone (GH), prolactin (PRL), and adenocorticotropin (ACTH) in addition to glycoprotein hormones. Given the significant proportion of immunoreactive cells for gonadotropins and alpha-subunit, in tumors characterizedas null cell adenomas and oncocytomas, imrnunocytochemistry may provide valuable information to the pathologist and clinical endocrinologist contributing to the evaluation of this heterogeneous group of tumors.     

垂体生长激素分泌瘤细胞有关生长抑素调节的受体和受体后过程的某些变化

为了解生长抑素（ＳＲＩＦ）在人垂体生长激素（ＧＨ）分泌瘤发病中的作用，在２５例肢端肥大症患者体外地养的垂体瘤细胞观察了ＳＲＩＦ激动剂（ＳＭＳ），抑制性鸟苷酸调节蛋白（Ｇｉ）拮抗剂百日咳毒素（ＰＴ）和钙离子载体Ａ２３１８７对ＧＨ分泌的影响．以及ＳＭＳ对细胞内ｃＡＭＰ水平的抑制作用。发现：ＳＭＳ可以使８４．０％（２１／１２５例）的ＧＨ瘤细胞ＧＨ分泌量明显抑制，揭示ＳＲＩＦ受体及受体后过程的功能基本正常；在３１．６％（６／１９例）患者的ＧＨ瘤细胞ＰＴ不能阻断ＳＭＳ对ＧＨ分泌的抑制作用，提示这些瘤细胞膜上Ｇｉ的功能异常；在３５．０％（７／２０例）用者的ＧＨ瘤细胞Ａ２３１８７未能拮抗ＳＭＳ对ＧＨ分泌的抑制作用，说明ＳＲＩＦ对Ｃａ￣（２＋）通道功能的调节有异常。在部分瘤细胞ＳＭＳ对ＧＨ分泌和细胞内ｃＡＭＰ的作用不一致。上述结果表明ＳＲＩＦ对垂体ＧＨ瘤细胞ＧＨ分泌的抑制作用由第二信使介导，但部分瘤细胞存在着受体后Ｇｉ和／或Ｃａ￣（２＋）通道功能的缺陷。     

Mapping of somatostatin receptor types in GH or/and PRL producing pituitary adenomas

BACKGROUND: Somatostatin is a tetradecapeptide exerting inhibitory action on endocrine and exocrine cell secretion and proliferation. Somatostatin receptors (SST) are widely expressed in various neoplasms including endocrine tumours. Using immunohistochemistry, the expression of SST(1), SST(2A), SST(2B), SST(3), SST(4), and SST(5) was studied in tissue microarrays (TMAs), using a series of 90 human pituitary adenomas producing growth hormone and/or prolactin, including 30 of each somatotroph, lactotroph, and mixed somatotroph/lactotroph adenoma type. METHODS: For immunohistochemistry, the standard avidin biotin complex method enhanced by tyramide was used, using polyclonal antisera for all SST types. A four point scoring system was used to assess the membranous immunopositivity. RESULTS: All SST types were positive in all tumour types, showing varying immunoreactivity scores. SST(5) and SST(2A) were the predominant receptors, showing strong expression in high frequency in all three adenoma types. Strong expression of SST(1) was higher in lactotroph adenomas than in other tumour types. CONCLUSIONS: The immunohistochemical results of SST expression are in agreement with most findings of previous molecular studies. The fact that SST(2A) expression is predominant suggests that pharmaceutical octapeptide somatostatin analogues may act through this receptor, while the role of SST(2B) may be merely synergistic.     

Histopathological analyses of silent pituitary somatotroph adenomas using immunohistochemistry, in situ hybridization and confocal laser scanning microscopic observation

To characterize the morphological and functional aspects of silent somatotroph adenomas with paradoxical responses of GH in TRH or GnRH provocation tests, which are considered to be a useful strategy for endocrinological identification of silent somatotroph adenomas, we examined three silent somatotroph adenomas histopathologically. The adenomas were investigated by immunohistochemistry, including the highly sensitive catalyzed signal amplification system, the non-radioisotopic in situ hybridization method, and confocal laser scanning microscopy. GH production and GH-immunopositive secretory granules in the adenoma cells were demonstrated histopathologically, and the adenomas were interpreted as being densely granulated somatotroph adenomas. Endocrinological identification of silent somatotroph adenomas in combination with paradoxical responses of GH in TRH or GnRH provocation tests may elucidate the increasing number of silent somatotroph adenomas that have been regarded as mammotroph or clinically inactive adenomas. One should be aware of the differences between the previously reported silent somatotroph adenomas, most of which are sparsely granulated somatotroph adenomas, a somatotroph adenomas with paradoxical and the silent somatotroph adenomas, most of which are sparsely granulated somatotroph adenomas, and the silent somatotroph adenomas with paradoxical responses of GH in TRH or GnRH provocation tests, which are densely granulated somatotroph adenomas.     

A morphological and functional study of the cavo-hepatic junction in the human

Summary The authors studied the morphological and structural aspects of the junctions between the hepatic veins and the inferior vena cava. The study was carried out on 20 specimens obtained from adult cadavers of both sexes, fixed in 10% formaldehyde solution. The hepatic veins with their junctions on the inferior vena cava were isolated. Then a macroscopic analysis of the openings of the hepatic veins into the inferior vena cava was performed. Part of this material was embedded in paraffin, submitted to serial sectioning and stained with Azan's trichrome and resorcin-fuchsin. Three hepatic veins were observed in all cases: right, left and the middle. In 20% of the cases the middle hepatic vein opens directly into the inferior vena cava. The hepatic vein openings are supported by two pillars inferiorly united through a semilunar fold. The hepatic vein wall is greatly thickened at the level of its junction with the inferior vena cava, showing a large ammont of muscular and collagenous fibers. These bundles constitute a sphincter-like formation which may play a physiological role in the control of the hepatic circulation.Les auteurs étudient les aspects morphologiques et structuraux du carrefour hépatico-cave. Cette étude porte sur 20 sujets adultes des deux sexes après formolisation. Les veines hépatiques et leurs terminaisons dans la veine cave inférieure sont prélevées, étudiées sur le plan macroscopique et incluses dans la paraffine. Les coupes sériées sont fixées selon la technique d'Azan. Trois veines hépatiques sont retrouvées dans tous les cas : les veines hépatiques droite, moyenne et gauche. Dans 20% des cas, la veine moyenne s'ouvre directement dans la veine cave inférieure. L'ostium des veines hépatiques s'appuie sur deux piliers réunis à leur partie inférieure par un repli semilunaire. La paroi des veines hépatiques au niveau de leur ostium est très épaisse avec un fort contingent de fibres musculaires et collagènes. Les fibres musculaires réalisent un véritable sphincter qui peut jouer un rôle physiologique dans le contrôle de la circulation hépatique.This report was made at the Anatomy Department of the Biological Sciences Center of UFPE     

Coexpression of galanin and adrenocorticotropic hormone in human pituitary and pituitary adenomas.

Galanin is a neuropeptide that regulates the secretion of several pituitary hormones, including prolactin (PRL) and growth hormone (GH). Galaninlike immunoreactivity (Gal-IR) and galanin mRNA in the rat anterior pituitary is cell lineage specific, with predominant expression in lactotrophs and somatotrophs. The authors examined the cellular distribution of human Gal-IR in seven normal postmortem pituitaries and 62 pituitary tumors by immunoperoxidase staining. In contrast to the rat, Gal-IR in human anterior pituitaries was present in corticotrophs scattered throughout the gland, but not in lactotrophs, somatotrophs, thyrotrophs, or gonadotrophs. Distinct Gal-IR also was present in hyperplastic and neoplastic corticotrophs in 19 of 22 patients with Cushing's disease. In noncorticotroph cell tumors, unequivocal Gal-IR was present in 5 of 11 GH-secreting tumors associated with clinical acromegaly, 9 of 18 nonfunctioning pituitary adenomas, and 2 of 14 prolactinomas. Of these galanin-positive tumors, four of the five GH-secreting adenomas, six of the nine nonfunctioning adenomas, and both of the prolactinomas also contained adrenocorticotropic hormone immunoreactivity (ACTH-IR). Immunostaining and in situ hybridization on adjacent sections using an 35S-labeled probe complementary to human galanin mRNA demonstrated predominant galanin expression in normal corticotrophs. Immunoelectron microscopy confirmed the presence of Gal-IR in pituitary cells characteristic of corticotrophs in both normal and neoplastic pituitaries. Thus, as in the rat, galanin gene expression in the human pituitary is cell-type specific. Unlike the rat, however, human galanin gene expression is restricted to the corticotroph lineage. Studies of tumors confirmed the observed coexpression of galanin and adrenocorticotropic hormone. The divergent cell type specificity of galanin production in human and rat pituitaries reflects different patterns of gene activation in these two species. In addition, these results suggest that galanin in the human pituitary may participate locally in the regulation of the hypothalamic-pituitary-adrenal axis.