Ultrastructure of Warthin's tumor

Pathogenesis of Warthin's Tumor: Neoplastic or Non-Neoplastic?

Warthin's tumor is the second most frequent neoplasm next to pleomorphic adenoma in the salivary gland, mostly in the parotid gland. The epithelial cells constituting a tumor are characterized by the presence of mitochondria that undergo structural and functional changes, resulting in the development of oncocytes. In addition to containing epithelial cells, Warthin's tumors contain abundant lymphocytes with lymph follicles (germinal centers) that are surrounded by epithelial cells. The pathogenesis of Warthin's tumor is not fully understood, and several hypotheses have been proposed. The risk factors for the development of Warthin's tumor, which predominantly occurs in males, include aging, smoking, and radiation exposure. Recently, it has been reported that chronic inflammation and aging cells promote the growth of Warthin's tumor. Several reports regarding the origin of the tumor have suggested that (1) Warthin's tumor is an IgG4-related disease, (2) epithelial cells that compose Warthin's tumor accumulate mitochondria, and (3) Warthin's tumor is a metaplastic lesion in the lymph nodes. It is possible that the pathogenesis of Warthin's tumor includes mitochondrial metabolic abnormalities, accumulation of aged cells, chronic inflammation, and senescence-associated secretory phenotype (SASP). In this short review, we propose that DNA damage, metabolic dysfunction of mitochondria, senescent cells, SASP, human papillomavirus, and IgG4 may be involved in the development of Warthin's tumor.

Biomarkers of mitochondrial origin: a futuristic cancer diagnostic

Cancer is a highly fatal disease without effective early-stage diagnosis and proper treatment. Along with the oncoproteins and oncometabolites, several organelles from cancerous cells are also emerging as potential biomarkers. Mitochondria isolated from cancer cells are one such biomarker candidates. Cancerous mitochondria exhibit different profiles compared with normal ones in morphology, genomic, transcriptomic, proteomic and metabolic landscape. Here, the possibilities of exploring such characteristics as potential biomarkers through single-cell omics and Artificial Intelligence (AI) are discussed. Furthermore, the prospects of exploiting the biomarker-based diagnosis and its futuristic utilization through circulatory tumor cell technology are analyzed. A successful alliance of circulatory tumor cell isolation protocols and a single-cell omics platform can emerge as a next-generation diagnosis and personalized treatment procedure.

Multiple muscle cell alterations in a case of encephalomyopathy

Skeletal muscle from an encephalomyopathy was examined by morphological and biochemical modalities. Mitochondria displayed variability in size, numbers per myocyte, and morphology. Certain organelles had stacks of dense cristae, others contained variable numbers of crystalloids or several lipid droplets. In isolated skeletal muscle mitochondria, oxidative phosphorylation was reduced, but activities of the electron transport chain components were unaffected. This is the second case of adult onset encephalomyopathy with a phenotype overlapping MERRF and Kearns-Sayre syndrome associated with a heteroplasmic mtDNA 3255G > A mutation in the tRNA(UUR(LEU)). This study emphasizes the desirability of a multidisciplinary approach in the diagnosis of complex myopathies.

Mitochondrial Markers for Cancer: Relevance to Diagnosis, Therapy, and Prognosis and General Understanding of Malignant Disease Mechanisms

Cancer cells display changes that aid them to escape from cell death, sustain their proliferative powers, and shift their metabolism toward glycolytic energy production. Mitochondria are key organelles in many metabolic and biosynthetic pathways, and the adaptation of mitochondrial function has been recognized as crucial to the changes that occur in cancer cells. This paper zooms in on the pathologic evaluation of mitochondrial markers for diagnosing and staging of human cancer and determining the patients’ prognoses.

Dynamic organization of mitochondria in human heart and in myocardial disease

Heart mitochondria, which, depending on their location within cardiomyofibers, are classified as either subsarcolemmal or interfibrillar, are the major sources of the high energy compound, adenosine triphosphate. Physiological differences between these two populations are reflected by differences in the morphology of their cristae, with those of subsarcolemmal mitochondria being mostly lamelliform, and those of interfibrillar mitochondria being mostly tubular. What determines the configuration of cristae, not only in cardiac mitochondria but in mitochondria in general, is unclear. The morphology of cardiac mitochondria, as well as their physiology, is responsive to the exigencies posed by a large variety of pathological situations. Giant cardiac mitochondria make an appearance in certain types of cardiomyopathy and as a result of dietary, pharmacological, and toxicological manipulation; such megamitochondria probably arise by a combination of fusion and true growth. Some of these enlarged organelles occasionally contain a membrane-bound deposit of beta-glycogen. Those giant mitochondria induced by experimental treatment usually can be restored to normal dimensions simply by supplying the missing nutrient or by deleting the noxious substance. In some conditions, such as endurance training and ischemia, the mitochondrial matrices become pale. Dense rods or plates are present in the outer compartment of mitochondria under certain conditions. Biochemical alterations in cardiac mitochondria appear to be important in heart failure. In aging, only interfibrillar mitochondria exhibit such changes, with the subsarcolemmal mitochondria unaffected. In certain heart afflictions, biochemical defects are not accompanied by obvious morphological transformations. Mitochondria clearly play a cardinal role in homeostasis of the heart.

Drug-induced increased mitochondrial biogenesis in a liver biopsy

Oncocytic changes seen in hepatocytes in patients receiving highly active antiretroviral therapy (HAART) are a result of mitochondrial damage. This is the first report that provides the electron microscopy illustration of mitochondrial proliferation as a result of the HAART drug Stavudine (Zerit) hepatotoxicity. The drug's effect on mitochondrial DNA replication leads to depleted mitochondrial-encoded proteins and configurational defects of the mitochondrial inner membrane leading to reduced and abnormal cristae, which house the electron transport chain and elementary bodies. This results in a decrease in the NAD/NADH ratio and reduces oxidative phosphorylation. The shift in the NAD/NADH ratio decreases the rate of fatty acid beta oxidation and oxidation of pyruvate by the Krebs cycle. Decreased oxidation of pyruvate drives it into an alternative pathway to form lactate leading to lactic acidosis. This mitochondrial dysfunction results in a compensatory increase in mitochondrial biogenesis, which results in oncocytic changes of the hepatocytes.

Megamitochondria formation - physiology and pathology

Mitochondria undergo structural changes simultaneously with their functional changes in both physiological and pathological conditions. These structural changes of mitochondria are classified into two categories: simple swelling and the formation of megamitochondria (MG). Data have been accumulated to indicate that free radicals play a crucial role in the mechanism of the MG formation induced by various experimental conditions which are apparently various. These include ethanol-, chloramphenicol- and hydrazine-induced MG formation. Involvement of free radicals in the mechanism of MG formation is showed by the fact that MG formation is successfully suppressed by free radical scavengers such as alpha-tocopherol, coenzyme Q(10), and 4-OH-TEMPO. Detailed mechanisms and pathophysiological meanings of MG formation still remain to be investigated. However, a body of evidence strongly suggests that enormous changes in physicochemical and biochemical properties of the mitochondrial membranes during MG formation take place and these changes are favorable for membrane fusion. A recent report showed that continous exposure of cells with MG to free radicals induces apoptosis, finding which suggests that MG formation is an adaptative process to unfavorable environments at the level of intracellular organelles. Mitochondria try to decrease intracellular reactive oxygen species (ROS) levels by decreasing the consume of oxygen via MG formation. If mitochondria succeed to suppress intracellular ROS levels, MG return to normal both structurally and functionally, and they restore the ability to actively synthesize ATP. If cells are additionally exposed to excess amounts of free radicals, MG become swollen, membrane potential of mitochondria (DeltaPsim) decreases, cytochrome c is released from mitochondria, leading to activation of caspases and apoptosis is induced.

Parotid Warthin's tumour Bristol Royal Infirmary (1985-1995): a study of histopathology in 33 cases

This is a study of 33 (32 patients) confirmed Warthin's tumours (adenolymphomas) treated surgically at Bristol Royal Infirmary (1985--1995) focussing specifically upon 17 salient histopathological features together with capsular measurement by micrometry. Twenty-four out of 33 tumours had 'thin' capsules (< or = 200 microm), whereas 5/9 'thick' capsules were associated with gross tumour degeneration. The degenerative features including cystic change, squamous metaplasia, corpora amylacea like bodies, etc. were quantified. Tumours were classified into subtypes (typical, stroma poor, etc). These variations were not associated with age or sex. In 20/33 tumours a marginal sinus suggested a lymph node origin. Fine needle aspiration cytology (FNA) smears showing degeneration features are a diagnostic problem, but histopathological features are reflected in such smears and their recognition enhances diagnostic precision, enabling controlled surgical enucleation, the ideal operation, to be performed in most cases. In this study only 12 tumours were so treated; 11 others received parotidectomy. The theories of histogenesis are reviewed and discussed.

Random cytochrome-C-oxidase deficiency of oxyphil cell nodules in the parathyroid gland. A mitochondrial cytopathy related to cell ageing?

Cytochrome-c-oxidase (complex IV) was histochemically studied in oncocytic adenoma (n = 10) and carcinoma of the thyroid gland (n = 3), cystadenolymphomas and oncocytic adenomas of the major salivary glands (n = 9), oncocytic neoplasia of the kidney (n = 1) and in 21 parathyroid glands with primary hyperparathyroidism and adenomatous proliferation (n = 17) and secondary hyperparathyroidism with hyperplasia (n = 4). Only in the parathyroids defects of cytochrome-c-oxidase were found being expressed in all 4 glands with hyperplasia (14 defects) and in 5 of the 17 adenomas (11 defects). All defects were confined to foci with oxyphil cell differentiation, the defect areas varying from 0.09 to 21.10 sq mm in hyperplastic glands and from 0.11 to 13.88 sq mm in adenomas, the size of the oxyphil foci varying from 0.12 sq mm-105.38 sq mm. However, not every oxyphil nodule of a gland was devoid of cytochrome-c-oxidase activity. Of 6 predominantly oxyphil adenomas, 4 showed no defects. No defects were observed either in 2 adenomas without oxyphil cells. Further enzymes of the respiratory chain, succinate dehydrogenase (complex II) and ATP synthetase, (complex V) were devoid of defects. In parathyroids with hyperplasia and oxyphil areas, defects of cytochrome-c-oxidase occurred significantly more often and tended to be larger than in adenomas, statistical analysis revealing a significant correlation between the occurrence of defects and the number of oxyphil foci but not with the total oxyphil area.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural study of mitochondria in oncocytes

A number of mitochondria in oncocytes show pleomorphism by conventional electron microscopy. In an investigation of their stereostructure, specimens were obtained from 11 patients with Warthin's tumor, parts of which were used in the preparation of serial thin sections. It was revealed that cup-shaped and concentric ring forms of mitochondria resulted from invagination and that aberrant cristae such as the sheaflike and vesicular types were both derived from laminated cristae with vesicular structure.

Heterogeneity of keratin expression in epithelial tumor cells of adenolymphoma in paraffin sections

Immunohistochemical expressions of keratin polypeptides detected by monoclonal antibodies were described in tumor cells of adenolymphoma, and the possibility of intercalated duct and ductal basal cells in the salivary glands being the progenitors was discussed. Basal cells in the tumor showed positive staining for keratin nos. 8, 13, 16, 18 and 19 detecting for monoclonal keratin antibodies (PKK 1, K 4.62, K 8.12, K 8.13), columnar tumor cells displayed strongly positive reactions with RPN 1164 and K4.62 suggesting keratin nos. 8 and 19. Great heterogeneity of distribution for keratin polypeptides was displayed by epithelial cells of adenolymphoma. Intercalated duct cells of normal salivary glands reacted with RPN 1164, RPN 1165, K 4.62 and K 8.13 monoclonal antibodies, which indicates the presence of keratins 8 and 19; and ductal basal cells reacted with PKK 1, K 4.62 and K 8.12, suggesting nos. 8, 13, 16, 18 and 19 keratins. Distribution of involucrin was variable in tumor epithelium of adenolymphoma, and was negative in the normal gland. The immunohistochemical distribution of keratin types between basal tumor cells of adenolymphoma and ductal basal cells of the normal salivary gland was compared.

Malignant oncocytic carcinoid of the pancreas

We report a rare case of malignant oncocytic carcinoid of the pancreas including the diagnostic immunocytochemical and electron microscopic findings. In addition the tumor shows some unusual ultrastructural features: lamelliform cristae and cytoplasmic and nuclear crystalline structures.

Warthin's tumor: an ultrastructural and immunohistochemical study of basilar epithelium

The cellular characteristics of the basilar epithelium in Warthin's tumor have had limited investigation. Ultrastructural examination of basal cells in 9 Warthin's tumors reveals that in addition to numerous mitochondria these cells possess a rich complement of tonofilaments. However, in three examples there are a proportion of these tonofilament-rich cells that have a narrow band of microfilaments in the peripheral cytoplasm adjacent to the basal lamina. Frozen sections of Warthin's tumor and normal salivary glands, doubly labeled with rhodamine-phalloidin for actin and monoclonal antibody 312C8-1 for cytokeratin 14, show that normal myoepithelial cells of acini and intercalated ducts have both of these filaments, as do a proportion of basal cells in the tumor. There are distinct differences in the cytokeratin polypeptide complement between normal luminal and myoepithelial cells as well as between luminal and basal cells in Warthin's tumor. Differences occur in the cytokeratin profiles between the luminal and basal cells of Warthin's tumor and comparable cells in the normal gland; however, there continue to be some similarities in the cytokeratin polypeptides of myoepithelium and the basal cells of normal salivary ducts and the basal cells of Warthin's tumor. These findings show that basal cells in Warthin's tumor are a mixed population with some capable of differentiating as myoepithelial-like cells, and that this tumor could arise from any level of the normal salivary gland duct system.

Granular cell basal cell carcinoma

Granular cell basal cell carcinoma (BCC) is a rare histologic variant of BCC. In this, the third reported case, the tumor consisted almost entirely of granular cells. By electron microscopy, these cells were filled with pleomorphic lysosome-like granules lined by unit membranes and containing homogeneous or granular electron-dense bodies, membranous debris and amorphous material. The epithelial origin of the tumor was suggested by the characteristic light microscopic appearance of tumor cell islands with some areas of peripheral palisading, and was confirmed by electron microscopic features of numerous well-formed pentalaminate desmosome junctions and sparse cytoplasmic tonofilament bundles, some of which showed attachments to the desmosomes. Histochemical immunoperoxidase stains for lysozyme showed no cytoplasmic lysozyme activity, in common with other granular cell tumors, but ultrastructural examination did not reveal angulate bodies, in contrast to findings in non-epithelial granular cell tumors.

Age-related changes of rat submandibular gland: a morphometric and ultrastructural study

Age changes of the submandibular glands (SMG) of male rats were studied morphometrically and ultrastructurally from youth to old age. The most conspicuous feature of the aged SMG was regressive changes of the granular ducts. The extent and height of the granular ducts decreased as well as the content of mature secretory granules. These changes may play an important role for an individual rat, because the granular duct synthesizes many biological factors. Cytoplasmic crystalloids, salivary deposits and oncocytic transformation were also found in the SMG of rats more than 22-months-old. It was noticeable that the intercalated duct cells were especially affected by both crystalloid formation and oncocytic transformation.

Functioning oxyphil cell adenoma of the parathyroid gland: a clinicopathologic study of ten patients with hyperparathyroidism

Adenomas of the parathyroid gland, the majority of which are of the solitary chief cell type, are the most frequent cause of primary hyperparathyroidism. Parathyroid adenomas composed predominantly or exclusively of oxyphil cells are rare and were previously considered nonfunctioning. Among 160 consecutive patients with primary hyperparathyroidism who were explored surgically, ten (6.25 per cent) had adenomas of the oxyphil cell variety. The eight women and two men in this series ranged in age from 28 to 82 years (average, 58 years). The tumors weighed from 0.2 to 4.0 g (average, 1.2 g). Nine of the adenomas were located in the left neck, while the remaining tumor was in the right neck. Histologically, the tumors were composed almost exclusively of transitional and typical oxyphil cells. A residual "capsular" parathyroid composed of chief cells was identified in each case. Electron microscopy, phosphotungstic acid-hematoxylin staining, and the immunoperoxidase technique for cytochrome c oxidase showed the presence of numerous mitochondria in oxyphil cells. All patients had normal serum calcium levels four months to four years (average, 23 months) after removal of the neoplasms.

Squamous cell carcinoma arising in Warthin's tumor of the parotid gland. A light, electron microscopic, and immunohistochemical study

The fourth recorded squamous cell carcinoma arising in a pre-existing Warthin's tumor is reported. A gradual transition was noted from the mitochondria-rich epithelium of benign portions of the tumor to organelle-poor cells forming the areas of squamous metaplasia and carcinoma. Bundles of intermediate filaments corresponding to immunoreactive keratin were demonstrated in all epithelial parts of the tumor and also in the epithelium of a benign Warthin's tumor that was studied in parallel.

Distinctive subcellular alterations induced by hypertonic stress in sea urchin eggs

Sea urchin eggs continuously exposed to a hypertonic solution were ultrastructurally examined for osmotic-stress induced alterations. No fertilization membranes formed during the treatment and the surface-cortex complexes remained unaltered from the unfertilized state. However, the osmotic stress did induce a number of subcellular changes. During the first 30 minutes of the treatment the eggs formed many endoplasmic reticulum whorls and compacted Golgi body aggregations. Both of these new formations can be correlated with rapid changes in intracellular calcium, known to occur in hypertonic stressed eggs. Aggregations of mitochondria could be observed at later stages; these aggregations can also be related to subcellular stress and possible changes in internal calcium concentrations. The various morphological transitions within the cytoplasm, along with the lack of a cortical reaction in these eggs, not only supports the idea that calcium is released during parthenogenetic activation, but also suggests that this free calcium originates from stores other than the stores that are involved during fertilization or simple artificial activation.

Giant mitochondria in a pleomorphic adenoma of the submandibular gland

A benign pleomorphic adenoma of the submandibular gland was examined by electron microscopy. In some areas, the epithelial cells comprising the tumor formed ductlike structures surrounding a lumen filled with membrane vesicles. The cells actually abutting the lumens had giant mitochondria measuring up to 8 micrometers in diameter; such enlarged organelles were absent from immediately subjacent cells. The giant mitochondria exhibited a variety of cristal arrangements, the most common being a quasireticulate one. They often contained expanded cristae that enclosed a number of helical filaments. Bundles of 14-nm tubules with faintly discernible axial periodicity were frequently present in the matrix compartment, as were amorphous dense inclusions. The basis for the occurrence of giant mitochondria only in duct cells may reside in microenvironmental factors rather than in altered nuclear or mitochondrial genomes.

Retinal pigment epithelium: ring mitochondria and lesions induced by continuous light

Electron micrographs of avian retinal pigment epithelium (RPE) reveal a basal zone of abundant mitochondria, approximately 15% of which present ring-shaped profiles. We infer that these ring profiles represent cross sections of "donut-shaped" bodies, randomly deployed in the RPE mitochondrial zone. The per cent of all RPE mitochondria which are in the ring form increases with age, and is further increased in chicks reared under continuous light, an environmental condition leading also to light-induced avian glaucoma (LIAG). We calculate that a given mitochondrion, on assuming the ring form, would more than double its surface area. Thus the RPE mitochondria of chicks developing LIAG may present to the surrounding cytoplasm a total surface area more than fourfold greater than in normal chicks.

Electron microscopy of liver lesions in primary biliary cirrhosis. I. Intrahepatic bile duct oncocytes

Liver biopsy specimens from a primary biliary cirrhosis (PBC) patient and two control patients with other biliary disorders were examined under the electron microscope, with special reference to intrahepatic bile ducts. The PBC patient had a bile duct with an 80 micrometers diameter that showed specific alterations in epithelial cells. These cells were termed oncocytes, and their main features were: the presence of a large number of swollen mitochondria with abnormal cristae, no mitochondrial bodies, small number of exocrine granules and an undulated nucleus with a large cytoplasm. The number of mitochondria per ultrathin-sectioned epithelial cell was greater by about 2 times in the oncocytic epithelial cells compared to the control cells. Fine fibrils and long-spacing collagens were present around the PBC bile duct. Periductal capillaries of the bile duct had multilayered basement membranes. These periductal changes may have induced the oncocytic changes in the epithelial cells. The basement membrane of the bile duct was meandrous and often disrupted, but not multilayered. Many lymphocytes and macrophages infiltrated among the epithelial cells.

Morphologic changes in rat parotid following isoproterenol administration and fractionated x-irradiation

The effects of fractionated X-irradiation following isoproterenol (IPN) administration on rat parotid gland were studied 4, 8, and 12 weeks post-irradiation. Degenerative and necrotic changes of the acinar cells were observed at all three time intervals as a result of the radiation. These changes were more obvious 4 and 8 weeks post-irradiation and isoproterenol administration. The necrotic acinar cells were replaced by fibrous connective tissue, especially conspicuous at 12 weeks. Reparative changes were observed along with the degenerative and regressive phenomena of the gland. Enlarged acinar cells and nuclei were observed as early as 4 weeks post-irradiation. This change was focally distributed at the 4-week interval but more widespread 8 and 12 weeks post-irradiation. Mitochondrial hyperplasia with alteration of mitochondrial cristae was observed 12 weeks post-irradiation. Proliferation of cells of ductal origin and nodular proliferation of ducts were observed 12 weeks after isoproterenol administration plus X-irradiation. These proliferative phenomena may represent an early stage of tumor formation resulting from the combined effect of isoproterenol and X-irradiation on rat parotid gland.

Oncocytic bronchial adenoma. Histological, histochemical and ultrastructural study

Benign adenomas derived from the bronchial mucous glands are uncommon. Probably the least common variety is the oncocytomatous adenoma, this case being the second known example. The tumour was situated in the right main bronchus in a man aged 75. An oncocytomatous adenoma should be clearly distinguished from the common oncocytomatous change which affects the normal bronchial mucous gland cells seen in adults. The eosinophilic, columnar tumour cells seen by light microscopy contained numerous prominent mitochondria by electron microscopy and granules of serous secretion. Other tumour cells contained microfilaments and were perhaps of myoepithelial origin. The true oncocytomatous mucous gland adenoma needs to be distinguished from an oncocytomatous bronchial carcinoid tumour the cells of which contain dense core granules of neurosecretory type. The bronchial oncocytomatous adenoma appears to be a benign tumour with a close similarity to its counterpart occurring in the salivary glands.

Oncocytomas (oxyphil adenomas) of the lacrimal caruncle

Three cases of oncocytoma (oxyphil adenoma) of the lacrimal caruncle are reported. Transmission electron microscopy performed on one of the lesions confirms the tumour to be composed of cells containing abnormally large numbers of mitochondria. It is suggested that these tumours arise from accessory lacrimal glands or their secretory ducts.

Oncobytic papillary cystadenomatosis of the larynx: a clinicopathologic entity

A patient with numerous oncocytic lesions of the larynx is reported. Laryngectomy for a concurrent epidermoid carcinoma made it possible to study the entire laryngeal mucosa. A hyperplastic component to the oncocytic metaplasia of the ductal epithelium of the seromucinous glands resulted in a spectrum of lesions varying from simple oncocytic cysts to solid lesions that may be erroneously interpreted as true neoplasms (oncocytomas). Oncocytic papillary cystadenomatosis is a condition affecting the larynx in a diffuse fashion suggesting the need for follow-up on patients with biopsy proven oncocytic lesions.

Malignant oncocytoma of the nasal cavity

Malignant oncocytoma of the major salivary glands is uncommon. Those of the endocrine, minor salivary and mucous glands are certainly rare. A case of a slowly-growing, low-grade malignant oncocytoma of the nasal cavity in a 50-year-old male, with no lymph node or distant metastases or local invasion of vital adjacent structures, and treated with combined radiotherapy and radical surgery, has been presented. The literature has been briefly reviewed, and the histological types; the electro-microscopic, histochemical and clinical pictures; and the outlines of treatment of oncocytomas have been discussed.

Ultrastructure of oncocytic adenoma of the human pituitary gland

Two cases of oncocytic adenoma occuring in the pituitary are reported. Both were men aged 40 and 50 years respectively and there was no evidence of endocrine abnormality. In both the tumours many cells showed abundant acidophilic finely granular cytoplasm which had not stained positively with PAS-orange G stain. Electron microscopically the cells contained numerous mitochondria associated with marked reduction of other cytoplasmic organelles including the secretory granules.

Granular cell ameloblastoma: electron microscopic observations

A case of granular cell ameloblastoma was studied by light and electron microscopy. Histologically, the lesion resembled simple ameloblastoma, but differed from the latter in that it contained many cells with granular eosinophilic cytoplasm. Ultrastructurally, the cytoplasmic granules were identified as lysosomes. These organelles were particularly abundant in cells situated in the center of islands and clusters of neoplastic cells. Since no cytoplasmic components could be identified in any of these lysosomes, it was concluded that they are not engaged in autophagy or in remodeling of the neoplastic cells.

Pigmented cells in adenolymphoma (Warthin's tumor)

A study of a series of adenolymphomas showed the presence of pigmented cells in the lymphoid stroma in 85% of the cases. The pigmented cells contained light brown cytoplasmic pigment and manifested sudanophila, acid-fastness, silver reduction capacity, PAS positivity and yellow autofluorescence in ultraviolet light. The morphology, histochemical reactions and autofluorescence suggest that the pigmented cells are macrophages containing ceroid derived from breakdown of damaged organelles of the epithelial tumor cells. It is possible that these cells play a role in the elimination of undigestable pigment material present in the cystic spaces of the tumor.

Electron microscopic studies of the parathyroid gland of senile dogs

The parathyroid gland of healthy senile dogs aged 8.5 to 15 years was compared with that of mature control dogs by examination with the electron microscope. Preparations fixed by perfusion with glutaraldehyde showed the cytoplasmic matrix of most parenchymal cells to be uniformly dense. None of the cells were of the extremely light type and dark cells were much less frequently noted than in preparations fixed by immersion in glutaraldehyde or osmium tetroxide. Syncytial cells and so-called coloid follicles were more frequent in senile dogs than in control dogs. It was suggested that the content of the latter structures is not colloid but necrotic substance hiving origin from the parenchymal cells and that perhaps the occasional cells containing large, membrane-bound inclusions may be degenerating cells which ultimately produce this necrotic substance. Oxyphil cells and mitochondria-rich cells of another type were found in all senile dogs, but not in the controls. These cells, especially the mitochondria-rich cells, frequently contained bizarre mitochondria that were modified in shape, size and arrangement. The most striking feature of these mitochondria was the concentric arrangement of elongated mitochondria which seemed to consist of densely layered cup-shaped mitochondria. Such mitochondria were noted in all senile dogs aged ten years and over. The significance of mitochondrial ple-morphism in the parathyroid gland of senile dogs was discussed.

[Morphology of salivary gland diseases]

The human salivary glands represent a functional system with manifold responsibilities and interactions to the organism. The major and minor salivary glands show a common construction schedule consisting of an acinar functional system for the production of an enzyme- and mucin-containing primary saliva and a ductal functional system with manifold secretory, resorptive and regulatory responsibilities for the transport and the definitive composition of the saliva. The cyclic AMP and calcium iones localized in the glandular acini have an exceptional importance for the course of the secretory process. The neurohormonal control of the salivary secretion results by adrenergic and cholinergic transmitter substances. Moreover the secretory process shows a daily cycle combined with morphological alterations of the glandular cells (so called circadian structures). The fluid secretion of the salivary duct system (the output of sodium-, potassium- and chlorine-iones) represents an active energy-consumed transport process which will be regulated by several factors (autonomic nervous system, quantity of perfusion, hydrostatic pressure in the blood capillaries, transepithelial active transport by ATP-consumed pump systems). The striated ducts are the functional most important sector of the duct system for a rapid fluid- and electrolyte excretion. The terminal axons of the postganglionic sympathic and parasympathic neurits are characterized by spindle-shaped enlargements (varicosities) which contain neurosecretory granules. In the region of the acinar and intercalated duct cells a direct synaptic contact exists for the stimulation transmission, in the course of which the terminal axon contacts immediately with the effector cell by penetration of the basement membrane. The salivary glands form a part of the stabil tissues with reversible postmitotic cells in regard of the tissue regeneration. Under pathological conditions (inflammations, impediment of secretion fluid, radiation effects etc.) metaplasias and proliferations of the duct system arise with development of indifferent duct formations analogous to the type of an embryonal salivary gland. The terminal zone between intercalated and striated ducts represents an indifferent zone with large regeneratory potency. A special behaviour shows the myoepithelial cells which are developed as well to the outside of primitive embryonic duct buds as differentiated intercalated and striated ducts. Morphologically three types of diseases can be classified in the salivary glands: sialadenosis, sialadenitis and tumours.(ABSTRACT TRUNCATED AT 400 WORDS)

[Comparative light and electron microscopic studies of oncocytic pituitary adenomas (author's transl)]

In a collection of 108 surgically removed, light and electron microscopically studied pituitary tumors, 19 adenomas (17.6%) could be found of which oncocytic tumor cells constituted more than 50%. These showed histologically, in conformity with the criteria of oncocytes, a fairly broad cytoplasm with finely granular or, in part, finely vacuolar structures and distinct cell membranes. The nuclei were predominantly round and moderately rich in chromatin but also in part, pyknotic. In paraffin-embedded sections the tumors could not be distinguished with certainty from chromophobe or moderately granulated acidophil adenomas. In plastic-embedded sections they could be identified by the typical filmy and finely granular feature of the cytoplasm which was distinctly different from conglomerations of secretory granules. Ultrastructurally they were characterized by many densely packed mitochondria. These were, in part, hydropically swollen. Furthermore, 5 tumors exhibited increased hormone-synthesizing organelles, 2 of which induced an acromegaly. Probably the oncocytic pituitary adenomas are secondarily transformed chromophobe or moderately chromophil tumors which must be regarded as independent, for the most part endocrinologically inactive pituitary tumors. In addition to these purely or almost purely oncocytic tumors further 12 adenomas (11.1%) with oncocytic parts constituting between 10 and 50% of the tissue were in our collection. Of these, 5 were moderately or distinctly acidophil adenomas with clinical symptoms of acromegaly; 2 were, for the most part, mucoid cell adenomas with Nelson's syndrome.

Central adenocarcinoma of the mandible

A seemingly straightforward clinical diagnosis of ameloblastoma was made of a large radiolucent, multicystic lesion in the mandible. Biopsy and metastatic tumor work-up revealed the tumor to be primary in the mandible. A histopathologic diagnosis of papillary adenocarcinoma of salivary gland origin was made. This article reports a well-documented primary mandibular salivary gland tumor. A review of the literature and light and electron microscopic interpretation of this tumor are presented.