Heterogeneous pituitary adenomas

Summary The combined use of several histological procedures (i.e. conventional light microscopy, immunohistochemistry and electron microscopy) among 45 unselected pituitary adenomas demonstrated the existence of 9 tumors (20%) containing several identifiable adenohypophy seal cell types. Thecellular associations were between 2 or 3 identifiable cell types. Mammosomatotrophic tumors were the most frequent but not the only mixed type (somatomammocorticotrophic, somatocorticotrophic tumors were also found). The cellular components varied in size but the cells appeared randomly distributed in the tumors. In all the adenomas there was an unidentified cell component (no reactivity with antisera used) varying from sparse to numerous elements. On adjacent sections the adenomatous cells reacted with a single specific antiserum, but in two cases the immunohistochemistry on contiguous paraffin embedded sections did not confirm this with certainty. These results confirm those of others and a new term is purposed to designate these tumors: heterogeneous pituitary adenomas. According to the nature and the proportions of the cell components the heterogeneous adenomas were subdivided into two groups: a group A which comprised adenomas formed by a major identifiable cellular type associated with one or two other less frequent cell types, and a group B formed by a predominant unidentifiable (no reactivity with immunochemical stainings) cell type associated with one or two other identified cell types. The present morphofunctional classifications of pituitary adenomas should be modified to include homogeneous adenomas with a single cell type and heterogeneous adenomas with several cell types.     

Description of the structural control systems of ovum transport in the quail oviduct

Some electronmicroscropic and light microscopic aspects of the quail oviduct have been studied in relation to ovum transport. Previously it has been shown that in this smooth muscle there exist spontaneous coordinated electrical and mechanical activity which suggests a good electrical and mechanical coupling of the muscle cells. The structural basis for this coupling is not known. The majority of muscle cell contacts observed were simple appositions and intermediate junctions. Less numerous were attachments of the interdigitation type. No nexuses or tight junctions were seen. Mechanical stretching or contraction of cells induced with 10^-4 M carbachol did not affect the contacts. The fine structure of the muscle cells did not differ from that described for other smooth muscles. Electronmicroscopically the muscle cell bundles could not be distinguished into separate layers, in the light microscope the cell bundles were spirally arranged. Stretching of the oviductal strips to the length to which the ovum stretches the muscular wall during ovum transport caused re-orientation of the muscle cell bundles. One-directional stretching turned the axes of the muscle cells and the collagen bundles parallel, while stretching in two direction made the tissue look like a network. The re-orientation of muscle cell bundles may be of importance in producing forces in the muscular tunic during ovum transport. The nerve supply to the muscle cells was negligible. These and previous results show that structurally the muscular wall of the quail oviduct is a dynamic unity in which the ovum via stretch induces the electrical and mechanical activity throughout the tissue. Innervation may play a minor role in controlling the contractions.     

Null cell adenoma of the human pituitary

Summary Among 343 surgically-removed pituitary adenomas, 56 tumors were unassociated clinically or biochemically with increased hormone secretion and contained no adenohypophysial hormones by the immunoperoxidase technique, except for 10 cases in which a few scattered cells showed positive immunostaining for -TSH or -FSH, -EH, prolactin and/or -subunit. These tumors were chromophobic adenomas with no PAS, lead hematoxylin or carmoisine positivity and electron microscopy failed to reveal their morphogenesis. The term null cell adenoma of the pituitary is proposed to designate this tumor type. This term recognizes the most obvious features of these tumors: the absence of markers which would permit the disclosure of their cellular origin. Null cells are also found in the nontumorous adeno-hypophysis, suggesting that null cell adenomas derive from preexisting nonneoplastic null cells. The question of whether pituitary null cells are hormonally inactive committed precursors, uncommitted stem cells or dedifferentiated cells remains to be elucidated.This work was supported in part by Grant MA-6349 of the Medical Research Council of Canada and Grant 1 R01 CA 21905-01 awarded by the National Cancer Institute, DHEW     

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.     

Balloon cell nevus of the soft palate: an immunohistochemical and ultrastructural study

An ultrastructural analysis of oral balloon cell nevus of intramucosal type complemented with an immunohistochemical study was performed for the first time. The lesion was composed of large balloon cells with an admixture of small nevus cells and melanophages at the periphery. Balloon cells showed cytoplasmic accumulation of vacuoles of varying sizes and the presence of microgranular and vacuolated melanosomes were found. Residual cytoplasm contained no identifiable organelles. A spectrum of transitional forms between balloon cells and conventional nevus cells with microvacuoles was readily observed. Both cells exhibited intense immunoreactivity to multiple melanocytic markers. Ballooning phenomenon was not evident in melanophages containing a large amount of melanosome complex. It can be inferred, from the present and previous observations, that progressive vacuolization of melanosomes in nevomelanocytes may be responsible for the formation of peculiar ballooning appearance, suggesting an aberrant melanogenesis.     

Sparsely granulated prolactin cell adenomas of the pituitary gland

Summary The possible relationship between the preoperative plasma prolactin levels of patients having a sparsely granulated prolactin cell adenoma of the pituitary gland and the morphology of the tumors was studied by means of quantitative electron microscopy. To this end, a number of ultrastructural variables were chosen which are generally regarded to be indicative of cellular activity and which could be determined in a quantitative or semiquantitative way. These variables were determined in 19 adenomas from 17 patients and plotted against the corresponding prolactin levels. It appeared that marked endocrine activity was associated with a small number of granules per cell, a high frequency of exocytosis, and a marked development of the rough endoplasmic reticulum. Granule size and development of Golgi apparatus and lysosomes were not at all, or only poorly correlated with the plasma hormone levels. Finally, the number of mitochondria per cell showed a totally unexpected inverse correlation with endocrine activity. Due to the close mutual correlation existing between several of the variables investigated, combining them in a multivariate analysis did not significantly improve the correlation with the hormone level.     

Epithelial cell adhesion molecule expression in pituitary adenomas: an immunohistochemical study

An important amount of data correlating the expression of epithelial cell adhesion molecule (Ep-CAM) with cellular proliferation and de-differentiation could directly contribute to carcinogenesis. The aim of this study is to evaluate prognosis relevance of Ep-CAM expression in a group of pituitary adenomas. Epithelial cell adhesion molecule, proliferating cell nuclear antigen, and microvascular density labeling indices in pituitary adenomas were determined by immunohistochemistry on tissue samples obtained from each adenoma after surgery. We evaluated 45 adenomas. Sixty-two percent were nonsecretor adenomas and 37.8% were secretor tumors. Immunohistochemistry was scored for immunoexpression of Ep-CAM (cytoplasmic, membrane, and mixed pattern). Proliferating cell nuclear antigen and vascular density (CD34) labeling indices were assessed. Statistical significance was observed between Ep-CAM cytoplasmic immunoreactions (P = .000) and higher proliferating cell nuclear antigen (P = .001) in secretor adenomas compared with nonsecretor tumors. Vascular density labeling indices did not show statistical significance. Therefore, Ep-CAM could be evaluated to distinguish secretor and nonsecretor pituitary adenomas. These suggest that the markers could predict the growth potential of individual pituitary adenomas.     

Estrogen-induced hyperplasia and neoplasia in the rat anterior pituitary gland. An immunohistochemical study

Diethylstilbestrol (DES) treatment of weanling F344 female rats resulted in enlarged pituitary glands and diffuse pituitary prolactin (PRL) cell hyperplasia in all animals after 9 and 12 weeks of treatment. Serum PRL was significantly greater than in control rats (P less than 0.001). Immunohistochemical studies showed that most of the pituitary gland cells consisted of PRL cells. Ultrastructural studies showed increased numbers of PRL cells with hyperplasia of the rough endoplasmic reticulum and decreased numbers of secretory granules. There was a decrease in the relative number of growth hormone (GH) and other cell types in the anterior pituitary. Pituitary tumors and normal pituitary glands were dissociated with trypsin and maintained in culture for 3 weeks. The numbers of PRL and GH cells decreased with time in both groups, and there was an increase in the number of fibroblasts. Staining of the culture cells with neuron-specific enolase showed that the anterior pituitary cells were positive for this enzyme, while the fibroblastic cells were negative. When dissociated pituitary cells were cultured in the presence of 10(-9) M DES for 7 days, there was a 42% increase in the number of immunoreactive PRL cells. These results indicate that DES-treated rats provide an excellent model for study of the in vivo and in vitro regulation of pituitary hyperplasia and neoplasia.     

Myoendothelial contacts in arteriolosclerosis.

Human renal biopsies were examined electron microscopically to investigate close contacts between endothelial and smooth muscle cells in small arterioles. These myoendothelial contacts were seen in the form of cytoplasmic projections passing through fenestrae in the basal lamina. Most of these cell processes seem to arise from the endothelial cells. In the control vessels, the separation between the endothelial cells and smooth muscle cells of the tunica media is 0.09-0.27 microns. With arteriolosclerosis there is an increasing separation between the elements of the intima and the media, from 1.0 to 2.42 microns. In spite of this increasing separation, myoendothelial contacts maintain an intercellular space of 10-15 nm, as observed in the control vessels. At 2.42 microns of separation, the amount of extracellular material accumulated is such that the cells can no longer keep in contact. Break up of the myoendothelial contacts may be responsible for impairment of communication between the tunica intima and media in the vessel wall in arteriolosclerosis.     

Histologic and immunohistochemical study of clinically non-functioning pituitary adenomas

Seventy-five clinically non-functioning pituitary adenomas were characterized in terms of their histologic and immunohistochemical features. Fourteen adenomas (18.7%) were positive for hormones other than gonadotropins. These included two somatotroph adenomas, three lactotroph adenomas, four thyrotroph adenomas, four corticotroph adenomas and one unusual plurihormonal adenoma. Fifty-five adenomas (73.3%) were exclusively positive for one or more gonadotropin subunits (β-follicle stimulating hormone, p-luteinizing hormone, and α-subunit of glycoprotein hormones), but negative for other hormones such as growth hormone and β-thyrotropin. Histologically, a papillary arrangement along the capillary was most characteristically observed in the gonadotropin-positive adenomas. Five of six adenomas negative for any pituitary hormones exhibited the typical papillary structure. Thus, approximately 80% of clinically non-functioning adenomas constituted a single tumor group that shared the common histologic features of gonadotroph adenomas. These findings suggest that nearly all tumor types of clinically non-functioning adenomas can be diagnosed solely by light microscopy in combination with immunohistochemistry, and that the vast majority of them may be gonadotroph adenomas.     

An electron microscopic and immunohistochemical study of Merkel cell carcinoma

Two cases of Merkel cell carcinoma (MCC) were examined by electron microscopy and immunohistochemistry. Histologically, tumor cells, which extended from the dermis into the subcutis, showed anastomosing bands with partial trabecular pattern. The ultrastructural study showed tumor cells in case 1 with numerous neurosecretory granules. The number of granules in case 2, however, was smaller compared with that in case 1. Perinuclear bundles of filaments were present in case 2, but few bundles were observed in case 1. By immunohistochemistry, cytokeratin (CK)-8, -18, -19, and -20 and epithelial membrane antigen were stained positively within tumor cells in both cases. It was interesting that staining patterns of chromogranin A and of neuron-specific enolase were different in the two cases. These data indicated that CK-20 is a useful marker for diagnosing MCC and that ultrastructural and immunohistochemical differences in both cases were the result of phenotypic variation.     

Leiomyoblastoma of the uterus: an immunohistochemical and electron microscopic study of distinctive tumours with immature smooth muscle cell differentiation mimicking fetal uterine myocytes

AIMS: We present three distinctive uterine tumours which exhibited immature smooth muscle differentiation mimicking smooth muscle cells of the fetal uterus. METHODS AND RESULTS: The patients were 45, 46 and 49 years old, and all of them had simple hysterectomies. Grossly, all tumours were present in the uterine body, and two of the three tumours were well demarcated 60-mm and 85-mm lesions, and the other tumour was a small 25-mm incidental lesion within multiple conventional leiomyomas. The tumours had varied histological features and were composed of round epithelioid, rhabdoid and large vacuolated cells intermingled with spindle-shaped cells to various degrees. Although their round vesicular nuclei showed mild to moderate variation in size, prominent nuclear atypia was not seen. Necrosis and mitotic figures suggesting biological aggressiveness were not present in any of the tumours. Immunohistochemically, tumour cells were intensely positive for desmin and alpha-smooth muscle actin, whereas positivity for heavy molecular weight caldesmon was restricted. In addition, two cases were positive for non-muscle myosin heavy chain (SMemb). Ultrastructurally, most tumour cells contained various amounts of intermediate filaments which were occasionally abundant and aggregated as in rhabdoid cells. Well-developed myofilaments with focal densities were observed in only a few tumour cells. Intermediate filaments and bundles of thin filaments without dense bodies were often intermingled and they occasionally formed distinctive complexes with many irregular dense body-like structures and crystalloid bodies. Other cytoplasmic organelles including rather rich mitochondria, some rough endoplasmic reticulum and free ribosomes were also common. CONCLUSIONS: These findings support their immature smooth muscle cell differentiation which mimics the mesenchymal cells of fetal uterus during 14-26 weeks of gestation. The term 'uterine leiomyoblastoma' is thought to be appropriate for describing these distinctive immature smooth muscle tumours.     

The Kupffer cell in experimental extrahepatic cholestasis in the rat--a light microscopy, immunohistochemical and electron microscopy study

Kupffer cell phagocytic function is reduced in the presence of obstructive jaundice. To investigate possible mechanisms we report a study of the rat liver in extrahepatic cholestasis, using light microscopy, immunohistochemistry and electron microscopy, Immunohistochemistry was performed with monoclonal antibodies specific for rat Kupffer cells ED 1, ED 2 and ED 3 and monoclonal antibodies directed against class II antigens of the rat major histocompatibility complex Ox 3 and Ox 6. Extrahepatic cholestasis was produced by bile duct ligation. In bile duct ligated animals light microscopy showed proliferation of bile ductules and an increase in sinusoidal cells. Immunohistochemistry with ED 1, ED 2 and ED 3 demonstrated a marked increase in the number of positive cells, but few of these cells were positive with Ox 3 and Ox 6, whereas the proliferating bile ductules were strongly positive. Electron microscopy revealed two homogeneous granular substances within the sinusoidal lumen and loss of the space of Disse. Despite a reduction in Kupffer cell phagocytic function in obstructive jaundice there is an increase in Kupffer cells, but these cells appear to be in an inactivated state as few express class II antigens on their surface. Furthermore the granular substance within the space of Disse may interfere with function.     

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.     

Malignant Smooth Muscle Tumors of the Gastrointestinal Tract: An Ultrastructural Study of 20 Cases

Twenty malignant soft tissue tumors arising from the stomach or intestine have been studied by light and electron microscopy, and the clinical records of each patient reviewed. The tumors were all considered to be of smooth muscle origin by light microscopy: Ten were spindle cell and ten were epithelioid neoplasms. By electron microscopy, only five tumors possessed smooth muscle features. A sequence of dedifferentiation could be traced among the remaining cases, indicating that the epithelioid tumors are of smooth muscle derivation. Awareness of the broad spectrum of fine structure displayed by these neoplasms will facilitate their ultrastructural identification.     

Malignant Smooth Muscle Tumors of the Gastrointestinal Tract: An Ultrastructural Study of 20 Cases

Twenty malignant soft tissue tumors arising from the stomach or intestine have been studied by light and electron microscopy, and the clinical records of each patient reviewed. The tumors were all considered to be of smooth muscle origin by light microscopy: Ten were spindle cell and ten were epithelioid neoplasms. By electron microscopy, only five tumors possessed smooth muscle features. A sequence of dedifferentiation could be traced among the remaining cases, indicating that the epithelioid tumors are of smooth muscle derivation. Awareness of the broad spectrum of fine structure displayed by these neoplasms will facilitate their ultrastructural identification.     

低切应力对体外培养动脉形态学重建的影响

目的 研究低切应力对血管的生物学作用,探讨切应力与血管形态学重建的关系。方法 采用血管体外应力培养系统,培养猪颈总动脉,通过组织学、免疫组织化学和图像分析等方法,探讨低切应力作用下动脉重建的形态学改变。结果 切应力减小时,动脉发生显著的结构重建,其特征为管径缩小,壁面积减小,管壁增厚,壁厚／内径比增加;低切应力作用使动脉部分中膜VSMC由收缩型转变为合成型,表现为α-肌动蛋白含量下降,细胞核朝向改变,发生扭曲,变大变圆,核仁明显。结论 低切应力和血压改变所致的血管重建在形态学方面有很大不同,提示：切应力和血压改变对血管重建的作用机制不同;中膜VSMC的表型转换是低切应力引起血管重建的基础。     

Origin of lipofuscin granules in hybridoma cell culture

Central Research Laboratory, Kaunas Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR J. J. Bredikis.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 107, No. 3, pp. 363–367, March, 1989.     

TSC-36/FRP inhibits vascular smooth muscle cell proliferation and migration

OBJECTIVE: In-stent restenosis is a vascular proliferation/migration disorder characterized by hyperplasia of vascular smooth muscle cells (VSMCs). Because mounting evidence suggests that the therapeutic potential of anti-proliferation and anti-migration therapy, we investigated possible inhibitory effects of the matricellular protein TGF-beta-stimulated clone 36 (TSC-36) on vascular smooth muscle cell proliferation and migration in vitro and in vivo. METHODS: Human umbilical artery smooth muscle cells (SMCs) were treated with inducting agents daidzein or estradiol. TSC-36 expression was detected by nested competitive PCR and in situ hybridization. TSC-36 was expressed in Origami (DE3) cells. The recombinant protein was used to immunize rabbits to produce polyclonal antibodies. VSMCs were treated with various concentrations of recombinant TSC-36 (rTSC-36) protein and daidzein. The MTT assay was used to analyze for cell proliferation. A transwell system was used to detect cell migration. Flow cytometry was used to detect cell phase. A rat carotid artery balloon injury model was duplicated. The rats were treated with daidzein or solvent control. Animals were sacrificed 5 weeks later, and injured arteries were taken for pathology and histology. RESULTS: TSC-36 mRNA and protein expression was induced in SMCs. Cell proliferation and migration were inhibited by rTSC-36. rTSC-36 caused accumulation of SMCs in G2 phase. The inducting agent daidzein decreased neo-intima proliferation. TSC-36 mRNA and protein expression was induced and expressed in the neo-intima. CONCLUSION: TSC-36 can be induced in VSMCs and inhibits VSMCs proliferation in vitro and in vivo.