Acinar cell carcinoma of the pancreas showing finger-print-like zymogen granules by electron microscopy: immunohistochemical study

A rare case of finger-print-like zymogen granules shown by electron microscopy is reported. The patient was a 75-year-old man who was histologically and ultrastructurally confirmed to have acinar cell carcinoma of the pancreas. Frozen section and postmortem examination revealed that the tumor was made up of solid nests of cells resembling the appearance of normal pancreatic acini, showing polygonal cells which had round or oval nuclei, and rare mitotic figures. Zymogen-like granules, shown by eosinophilic granular staining, were abundant in the cytoplasm. Electron microscopy showed that the tumor cells were closely packed, occasionally forming small intercellular spaces resembling pancreatic acini (microtubules). The cytoplasm contained characteristic zymogen granules with dark-to-medium electron density, measuring 660 nm ± 213 SD in diameter. The granules of medium density were large, and showed finger-print-like patterns. Investigation of more cases is necessary to identify whether these finger-print-like patterns are an important factor in the genesis of acinar cell carcinoma. Received for publication on Jan. 8, 1999; accepted on Sept. 21, 1999     

Coexistence of reactive and nonreactive endocrine cells in the fundal mucosa in the rabbit]

Whether the same endocrine like cells are reactive towards different staining methods has been examined in normal and L-Dopa treated rabbits for distinction of cell types. Correlation with electron microscopy is proposed. It seems likely that SM cells (poorly reactive with Sevier-Munger technic) include two cell types: cells having around medium size and dense granules; cells having small round dense granules (D1?). X cells may correspond to a well defined group at the electron or photonic microscopic level. Insertion of D cells (according to Solcia and coworkers nomenclature) is not satisfactory but true non Apud cells are described. The signification of Jt (dim yellow) cells remains unknown.     

Cytological and functional studies of preosteoclasts and osteoclasts in the alveolar bones from neonatal rats using microperoxidase as a tracer

Summary Microperoxidase (MP) was used to investigate the cytological and functional features of preosteoclasts and osteoclasts during rat alveolar bone development. We observed mononuclear cells as preosteoclasts and multinuclear cells with and without ruffled borders (RB). In the bone facing multinuclear cells with RB as active osteoclasts, MP was extensively deposited along the external bone matrix undergoing resorption, and was phagocytosed with bone components into the vacuoles of osteoclasts. Neither preosteoclasts nor multinuclear cells without RB took up MP and bone components. Only multinuclear cells with RB seemed to resorb bone. Monocytes/macrophages (MMP) phagocytosed MP through all regions of the plasma membrane, whereas osteoclasts took up MP only through the RB which was a part of the plasma membrane. Endogenous peroxidase was detected in the MMP but not in preosteoclasts and osteoclasts. Thus, osteoclasts were considerably different from the MMP. The numbers of MMP were extremely few close to the osteoclasts, whereas moderate numbers of preosteoclasts were located close to the osteoclasts. Except for the nucleus and RB, there were many morphological similarities between preosteoclasts and osteoclasts. We therefore suggest that preosteoclasts, rather than MMP, are the precursors of osteoclasts during alveolar bone development of neonatal rats.     

Intercellular granules and vesicles in prolonged cerebral vasospasm

Prolonged vasospasm was produced in the dog basilar arteries by introduction of fresh arterial blood or norepinephrine into the chiasmatic cistern. Myonecrosis was limited to a small number of smooth-muscle cells, and a large number of muscle cells appeared intact. The most characteristic change was the appearance of aggregated granules and vesicles in the widened extracellular space between smooth-muscle cells, particularly near the adventitia and the elastic lamina. The granules were spherical, 50 to 100 nm in diameter, often surrounded by a single membrane, and contained a dense osmiophilic core, about 40 to 90 nm in diameter. In addition, the elastic lamina often became loose and corrugated or broken.     

Transdifferentiation of cultured human prostate cancer cells to a neuroendocrine cell phenotype in a hormone-depleted medium

Neuroendocrine (NE) cells are enigmatically found in association with human prostate cancers and their numbers are reported to increase in advanced and hormoneresistant tumors. The origin of this cell type and the reason for their appearance in prostate tumors remains unresolved. Previously, Bang et al. (Proc Natl Acad Sci USA 1994;91:5330) reported that dibutyryl adenosine 3',5'-cyclic phosphate (db-cAMP), an agent that upregulates intracellular cAMP, was able to induce a NE cell-like phenotype of cultured human prostate cancer cells, including the androgen-sensitive LNCaP line. Here we report that chronic incubation of LNCaP cells in a medium containing 10% charcoal-stripped fetal bovine serum (CSFBS) likewise induces NE differentiation of these cells. Within 5 days of switching low density cultures of LNCaP cells to this modified medium, the cells growth arrest and acquire an altered morphology with numerous cytoplasmic secretory granules and elongated processes that resemble cultured neurons. This morphology predominates at 10 days with complete transformation seen by 20 days of culture. Electron microscopic analysis of sections of CS-FBS maintained cells showed the presence of abundant dense core secretory granules characteristic of NE cells. Immunohistochemical staining identified the upregulation of the expression of NE markers bombesin, neuron-specific enolase, and S-100 in this modified culture medium. Once established, the NE cell-like phenotype was found to be reversible upon replacement with a medium containing unmodified fetal bovine serum, but not by direct supplementation of CS-FBS medium with dihydrotestosterone (DHT) (I nM). DHT supplementation did, however, suppress the development of the NE cell-like phenotype when it was present at the initiation of exposure to CS-FBS medium. In contrast to db-cAMP treatment, which did not affect prostate specific antigen (PSA) or androgen receptor (AR) expression of LNCaP cells, NE-differentiated LNCaP cells derived in this hormone-deficient medium showed marked downregulation of PSA and AR expression. These in vitro results further support the concept that prostate cancer cells can tranform in vivo to cells with a NE phenotype and suggest that this transformation might be accelerated in patients by certain therapies for prostate cancer.     

Primary pulmonary paraganglioma: report of a functioning case with immunohistochemical and ultrastructural study

We describe a case of primary pulmonary paraganglioma, a tumor that has not been reported in sufficient detail in previous literature. The patient was a 55-year-old woman with hypertension accompanied by an elevated serum norepinephrine level (2651 pg/mL; normal 100-450 pg/mL). Computed tomography revealed a well-circumscribed solid mass, 3.5 cm in diameter, located in the lower lobe of the left lung. In the lobectomy specimen, the tumor had invaded the B8 bronchus and hilar lymph nodes with microscopic metastasis to the mediastinal nodes. The tumor showed histologic, immunohistochemical, and ultrastructural features of paraganglioma: argyrophilic cells arranged in a nesting (Zellballen) or anastomosing trabecular pattern within an arcuate vascular network. Neoplastic chief cells positive for neuroendocrine markers (CD56, synaptophysin, chromogranin A) were surrounded by sustentacular cells positive for S-100 protein. Neurofilament protein was positively stained, but cytokeratins were totally negative. On electron microscopy, chief cells possessed abundant dense core granules with an eccentric halo ("norepinephrine-type" granules). The patient's blood pressure began to decline soon after the resection, and her serum norepinephrine promptly returned to almost normal. On the basis of our experience, our case is a bona fide primary pulmonary paraganglioma, a tumor heretofore subject to considerable skepticism.     

Effect of tobacco smoke exposure on rat tracheal submucosal glands: an ultrastructural study.

The ultrastructural appearance of rat tracheal submucosal glands after exposure to tobacco smoke for up to two years is described. Within the mucous cells many of the rough endoplasmic reticulum cisternae were grossly dilated with an accumulation of amorphous, electron-lucent material. The Golgi zones were prominent, and the secretion granules often contained dense cores, and appeared to have coalesced. Histochemically, increased amounts of sulphated mucus were present in exposed rats. Serous, ciliated, and myoepithelial cells were unaffected by smoke exposure.     

Study of immunoelectron microscopic localization of cathepsin K in osteoclasts and other bone cells in the mouse femur

The localization of cathepsin K protein in mouse osteoclasts was examined by immunolight and immunoelectron microscopy using the avidin-biotin-peroxidase complex method with anti-cathepsin K (mouse) antibody. With light microscopy, a strong immunoreaction for cathepsin K was found extracellularly along the bone and cartilage resorption lacunae and detected intracellularly in vesicles, granules, and vacuoles throughout the cytoplasm of multinuclear osteoclasts and chondroclasts attached to the surface of the bone or cartilage. Mononuclear cells, probably preosteoclasts, some distance from the bone also contained a few cathepsin K-positive vesicles and granules. Cathepsin K was sometimes found in the cisternal spaces of the rough endoplasmic reticulum and vesicles of the Golgi apparatus with electron microscopy of the basolateral region of the osteoclasts. Cathepsin K-positive vesicles and granules as lysosomal compartments were present in various stages of fusion with vacuoles as endosomal compartments that contained fragmented cathepsin K-negative fibril-like structures. Some of the vacuoles (endolysosomes), which seemed to be formed by this process of fusion, contained cathepsin K-positive vesicles and fibril-like structures that did not show the regular cross striation of type I collagen fibrils. In the apical region of the osteoclasts, cathepsin K-positive vesicles and pits had already fused with or were in the process of fusing with the ampullar extracellular spaces. There were large deposits of cathepsin K on fragmented fibril-like structures without regular cross striation in the extracellular spaces, as well as on and between the cytoplasmic processes of the ruffled border. There were also extensive deposits of cathepsin K on the type I collagen fibrils with cross striation in the bone resorption lacunae. Osteoblasts and osteocytes were negative for cathepsin K. In the immunocytochemical controls, no immunoreaction was found in the osteoclasts or preosteoclasts, or on the collagen fibrils in the resorption lacunae. The results indicate that cathepsin K is produced in mature osteoclasts attached to the bone and secreted into the bone resorption lacunae. The findings suggest that cathepsin K participates in the extracellular degradation of collagen fibrils in the resorption lacunae and in the subsequent degradation of the fragmented fibrils in the endolysosomes. It is also suggested that cathepsin K degrades the organic cartilage matrix.     

Endocrine diffuse system--histological and functional aspects interrelated with the tumoral pathology

It was first believed that all these endocrine cells are deriving from the neural crests; in time were discovered more than 40 different types of such cells with different origins and only 6 or 7 are deriving from the neural crests. Serotonin-secreting cells show yellow fluorescence, while those secreting cathecolamines show a green fluorescence, with formaldehyde. The most usual method for the stain of the cells of the endocrine diffuse system is the silver salts impregnation. In the electron microscopy the cells show dense granules, which are modified in appearance in the malignancies developed from such cells. Most of the hormones secreted in the intestine were found also to be hormones secreted in the central nervous system. The border between benign proliferation and malignant tumors arising from these endocrine cells is not well defined. DNES--diffuse neuroendocrine system.     

Granular Cell Tumor of the Breast Preoperatively Diagnosed by Fine-Needle Aspiration Cytology: Report of a Case

Granular cell tumors (GCTs) have a characteristic cytological appearance, and fine-needle aspiration cytology (FNAC) has been suggested to be the diagnostic modality of choice. However, the differential diagnosis has not yet been well described. We herein describe a rare case of GCT of the breast and discuss the differential diagnosis. A 53-year-old woman presented to our hospital with a left breast mass. In clinical and radiological examinations, the mass was suspected to be malignant. Cytologically, the tumor was composed of cohesive groups of cells with a syncytial appearance, and the cells contained abundant, finely eosinophilic cytoplasmic granules and small round-to-slightly-oval nuclei, thus suggesting the presence of benign GCT. The results of immunohistochemical staining supported the proposed deviation from Schwann cells. This case emphasizes the fact that GCTs are a rare but important possibility in the differential diagnosis of breast tumors, and that FNAC may provide clinically useful information on the management of such lesions.     

Electron microscopic observation of ependyma (author's transl)]

The fine structure of the normal ependymal cell has been described. The ependymal cells form a closely knit single layer lining the ventricles. They are bordered on one side by the ventricular lumen and by the neuropil on the basal surface. The luminal surface is characterized by microvilli and cilia. The former differ from those seen in the respiratory tract or intestine in that they have a smooth surface and are devoid of a coating material. They differ from the microvilli of the choroid plexus by being straight and relatively stubby. The cilia appear indistinguishable from those seen on other cells and display the usual 9+2 microtubuler structure. The apposing surfaces of adjacent ependymal cells show various junctional devices such as desmosomes and others, but apparently no true tight junction such as seen in the choroid plexus are present. The basal surface abuts directly on the neuropil usually with no intervening basement membrane. The cytoplasm contains usual organelles including fine (60-90 A) filaments and glycogen granules. The latter two structures become especially abundant under pathological conditions which elicit an ependymal response. These changes very closely resemble those seen in reactive astrocytes.     

Comparison in localization between cystatin C and cathepsin K in osteoclasts and other cells in mouse tibia epiphysis by immunolight and immunoelectron microscopy

We compared the distribution of a cysteine proteinase inhibitor, cystatin C, with that of cathepsin K in osteoclasts of the mouse tibia by immunolight and immunoelectron microscopy. Light microscopically, strong immunoreactivity for cystatin C was found extracellularly along the resorption lacuna and intracellularly in the organelles of osteoclasts. In serial sections, various patterns of cystatin C and cathepsin K localization were seen, specifically: (1) some resorption lacuna were positive for both cystatin C and cathepsin K; (2) others were positive for either cystatin C or cathepsin K, but not both; and (3) some lacuna were negative for both. In osteoclasts, the localization of cystatin C was similar to that of cathepsin K. Furthermore, cystatin C immunoreactivity was detected in preosteoclasts and osteoblasts, whereas cathepsin K was seen only in preosteoclasts. Electron microscopically, cystatin C immunoreactive products were found in the rough endoplasmic reticulum (ER), Golgi apparatus, vesicles, granules, and vacuoles of osteoclasts. These cystatin C-positive vesicles had fused or were in the process of fusion with the ampullar vacuoles (extracellular spaces) containing cystatin C-positive, fragmented, fibril-like structures. The extracellular cystatin C was deposited on and between the cytoplasmic processes of ruffled borders, and on and between type I collagen fibrils. In the basolateral region of osteoclasts, cystatin C-positive vesicles and granules also fused with vacuoles that contained cystatin C-positive or negative fibril-like structures. These results indicate that osteoclasts not only synthesize and secrete cathepsin K from the ruffled border into the bone resorption lacunae, but also a cysteine proteinase inhibitor, cystatin C. Therefore, it is suggested that cystatin C regulates the degradation of bone matrix by cathepsin K, both extracellularly and intracellularly.     

Glycogen in neuroblastomas. A light- and electron-microscopic study of 40 cases

A light- and electron-microscopic review of 40 cases diagnosed at Children's Hospital of Pittsburgh as ganglioneuroblastoma, neuroblastoma, or small round cell tumor-probably neuroblastoma disclosed four cases that contained abundant glycogen. Two were unquestionable neuroblastomas by electron microscopy; one was primary in the adrenal gland, the other in the mediastinum. In the third case, a paraspinal tumor, the light-microscopic appearance was suggestive or neuroblastoma, but no catecholamine granules or neural processes were demonstrated in the material available for electron microscopy. The fourth case was an undifferentiated malignant tumor in the pectoralis muscle of a 12-year-old girl. By electron microscopy, neural processes were demonstrated and the tumor was classified as peripheral neuroblastoma. Of the remaining 36 cases, electron microscopy readily indicated a diagnosis of neuroblastoma or glangioneuroblastoma in 35 of them. In the other case, the tissue had been fixed in formalin and only a few catecholamine granules were found after an extensive search.     

Malignant melanoma showing ganglioneuroblastic differentiation: report of a unique case.

We report a case of metastatic malignant melanoma in an inguinal lymph node, expressing ganglioneuroblastic differentiation. This was characterized by the presence of discrete nests and islands of large ganglion cells with abundant cytoplasm and eccentric nuclei with prominent nucleoli admixed with smaller primitive neuroblasts. The cells were separated by pale pink fibrillar material representing neuritic cell processes. These foci of ganglioneuroblastoma were seen over a background of an otherwise typical metastatic epithelioid, focally melanotic, malignant melanoma. Immunohistochemistry showed positivity for neurofilament, synaptophysin, chromogranin, vasoactive intestinal peptide, and glial fibrillary acidic protein in the areas with ganglioneuroblastic differentiation, but not in the melanocytic component. Conversely, HMB45 positivity was expressed by the melanocytic cells only. S-100 protein and Melan-A, a putative melanocytic marker, showed positivity in both melanocytic and ganglioneuroblastic components. Ultrastructurally, neuritic cell processes and dense core neurosecretory granules were identified in the ganglionic and neuroblastic cells. A subsequent nodal metastasis in the same region showed focal neuroblastic differentiation without the ganglionic element. No evidence of neuronal or ganglionic differentiation was seen in the primary skin melanoma.     

Thyroid pigments in Gunn rats]

The structural and histochemical characteristics of the thyroid pigment in homozygous Gunn rats were examined. The pigment occurs in the form of numerous yellow granules in the cytoplasm of the follicular cells. The focal depositions of the pigment were also seen in the central part of the luminal colloid. However, the pigment granules were not present in the light or parafollicular cells. The main histochemical properties of the pigment are that it is basophilic, PAS-positive, acid-fast and reducing toward alcaline silver nitrate and ferricyanide. Besides, it was easily bleached with oxidizing agents. It was deduced that the pigment was a lipofuscine. Ultrastructurally, pigment bodies are characterised by an electron dense content, and a smooth surface single limiting membrane. They resembled lysosomes or peroxisomes. It was concluded that the pigment granules visible at the light microscopic level resulted frim the accumulation of the pigment substance in the preexisting lysosomes.     

The fine structure of ependymona (author's transl)]

The tumor cells form an unoriented mass rather than a layered structure. Most of the cells have no ependymal specialization, such as cilia, microtubular, etc. Instead, they assume a primitive undifferentiated appearance with large nuclei and abundant free ribosomes. Occasionally, however, certain cells tend to form a ring around a narrow lumen-like space within the mass. Such spaces are virtually filled with microvilli and, occasionally, even cilia arising form the surrounding cells. Elaborate desmosomes decorate the apposing surfaces of such cells and basal bodies are presented within the cytoplasm. In addition, the tumor cells often display glial filaments, glycogen granules and microtubules, similar to the cells comprising astrocytomas. As is well known, astrocytomas and ependymomas are often found mixed in the same tumor.     

Evidence for neural origin and PAS-positive variants of the malignant small cell tumor of thoracopulmonary region ("Askin tumor")

The differential diagnoses of childhood and adolescent tumors composed of small round cells include a distinctive clinicopathological entity called malignant small cell tumor (MSCT) of the thoracopulmonary region in childhood. In the present study, 15 such tumors that fulfilled the criteria by Askin et al. were examined for features of possible neural differentiation by light and electron microscopy (EM). With hematoxylin-eosin stain (H&E) the tumors were made up of small undifferentiated cells; rosette formation was noticed in four cases. By immunohistochemistry all 15 tumors were positive for neuron/specific enolase (NSE), which is a specific marker for neural elements and their tumors including neuroblastomas. Ten of 15 MSCT had positive PAS staining. Ultrastructurally dense core (neurosecretory) granules and cell processes indicative of neuronal differentiation could be recognized in 10 of 14 tumors. The dense core granules were often atypical. Filamentous cytoskeleton, never observed in Ewing's sarcoma, was often present. Based on the current results, MSCT of the thoracopulmonary region can be considered a peripheral neuroectodermal tumor with the possible origin in intercostal nerves. MSCTs are generally misdiagnosed as Ewing's sarcoma due to their primitive appearance in H&E sections and their periodic acid-Schiff positivity. NSE immunostaining, preferably augmented by electron microscopy, is necessary for their correct diagnosis.     

Cytocompatibility of porous biphasic calcium phosphate granules with human mesenchymal cells by a multiparametric assay

This work aims to evaluate the cytocompatibility of injectable and moldable restorative biomaterials based on granules of dense or porous biphasic calcium phosphates (BCPs) with human primary mesenchymal cells, in order to validate them as tools for stem cell‐induced bone regeneration. Porous hydroxyapatite (HA) and HA/beta‐tricalcium phosphate (β‐TCP) (60:40) granules were obtained by the addition of wax spheres and pressing at 20 MPa, while dense materials were compacted by pressing at 100 MPa, followed by thermal treatment (1100°C), grinding, and sieving. Extracts were prepared by 24‐h incubation of granules on culture media, with subsequent exposition of human primary mesenchymal cells. Three different cell viability parameters were evaluated on the same samples. Scanning electron microscopy analysis of the granules revealed distinct dense and porous surfaces. After cell exposition to extracts, no significant differences on mitochondrial activity (2,3‐bis(2‐methoxy‐4‐nitro‐5‐sulfophenly)‐5‐[(phenylamino) carbonyl]‐2H‐tetrazolium hydroxide) or cell density (Crystal Violet Dye Elution) were observed among groups. However, Neutral Red assay revealed that dense materials extracts induced lower levels of total viable cells to porous HA/β‐TCP (P < 0.01). Calcium ion content was also significantly lower on the extracts of dense samples. Porogenic treatments on BCP composites do not affect cytocompatibility, as measured by three different parameters, indicating that these ceramics are well suited for further studies on future bioengineering applications.     

A Malar Granular Cell Tumor in a Djungarian Hamster

‘Granular cell’ tumor observed in the malar subcutis of a Djungarian hamster was examined to determine its cellular origin. Histologically, the tumor consisted of a solid growth of oval or spindle‐shaped large cells with abundant cytoplasm filled with eosinophilic granules that were periodic acid‐Schiff‐positive and diastase‐resistant. Immunohistochemically, the tumor cells were positive to anti‐vimentin and anti‐desmin antibodies and a few cells showed positivity to anti‐actin antibody as well. They did not react to myoglobin, S‐100 protein, and glial fibrillary acidic protein (GFAP). Electron microscopic studies revealed that the tumor cells had pinocytotic vesicles, dense plaque and microfilaments. The first granular cell variant of myogenic tumor reported here in Djungarian hamsters was differentiated from granular cell tumor of Schwann cell origin.