Increased tight junction width in two children with Ménétrier's disease

Protein-losing enteropathy (PLE) and edema are usually the most prominent clinical features in children with Ménétrier's disease. However, the changes in gastrointestinal mucosa that can cause PLE have not been described yet in children. We studied by electron microscopy the mucosa of the gastric fundus, which is the site where macroscopic changes are most prominent, in two children with Ménétrier's disease. We found that tight junction width was increased to 10.5 +/- 0.94 nm (mean +/- 1 SD) in one child and to 9.7 +/- 0.7 in the other. Tight junction width returned to normal when PLE and edema subsided. These ultrastructural changes were similar to those described in adults with the disease, although the clinical course of Ménétrier's disease is very different in adults and in children. Both patients showed evidence of cytomegalovirus (CMV) infection, as indicated by increasing IgG antibodies against the virus or recovery of the virus in the urine. Although Helicobacter pylori was found in the antral mucosa of one patient, the clinical course of the disease was not related to this microorganism. We conclude that increased tight junction width plays a role in PLE seen in Ménétrier's disease in children and that CMV, rather than Helicobacter pylori, is associated with the disease.

Morphometric evaluation of intracytoplasmic lipid in normal and pathological parathyroid glands

The chief morphological criterion for classifying parathyroid glands as 'normal', 'suppressed', or 'activated' is the lipid content of the cytoplasm. In particular, cytoplasm lipid deposit is scanty in the active parathyroid cell, according to many authors. In this paper we present the results of a morphometrical study of ten normal parathyroid glands from patients undergoing thyroidectomy, 20 enlarged 'adenomatous' glands from patients with primary hyperparathyroidism, and 20 glands of normal size from the same hyperparathyroid patients. We aimed at assessing the content of intracytoplasmic lipid of secretory cells in all these conditions. The results show that secretory cells of adenomatous glands have less lipid than those from normal glands; however, there was considerable overlapping of the data in the two groups. The mean lipid content of cells in glands of normal size taken from hyperparathyroid patients was not significantly different from the mean value of normal cells, even when ultrastructural evidence of activation was present in the former. These data suggest that caution has to be exercised in assessing the functional status of parathyroid glands on the basis of lipid content of secretory cells, mainly when differentiating between adenoma and hyperplasia.

Scanning electron microscopy of the small intestine mucosa in children with celiac disease after long-term dietary treatment

Jejunal mucosal specimens from twenty children with celiac disease were studied by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) after one year of dietary treatment. An ultrastructural morphometric study was performed in five patients who had an intestinal permeability (IP) test. Seventeen patients were tested for serum antigliadin antibodies (AGA). In ten children, in whom LM showed partial villous atrophy, SEM and TEM examination confirmed the lesion. In the second group (10 children) with normal morphology at routine LM, SEM showed lesions of variable degree in 70% of cases. The morphological ultrastructural investigation showed good correlation with the immunological and functional data (IP test): ultrastructural damage of the jejunal mucosa after one year of a gluten-free diet was found in patients with positive serum AGA and an abnormal IP test. Furthermore, the morphometric study of the ultrastructural alterations allowed a quantitative, closer correlation between morphological and functional data. Our results suggest: 1) SEM and TEM investigations offer additional and more complete information on celiac patients, over LM alone. 2) The morphometric evaluation of the ultrastructural alterations highlights quantitative and reproducible correlations between morphological and clinical data, not strengthened by the subjective, qualitative study.

S-100 protein in white preadipocytes: an immunoelectronmicroscopic study

Differentiation of adipocytes from their precursor cells (preadipocytes) is an important problem in the study of the pathogenesis of obesity. Unfortunately, among the immature stages of adipocytes, only relatively differentiated forms can be identified by their fine structure; because early preadipocytes cannot be distinguished from fibroblasts solely on the basis of their morphology, it is impossible to assess the size of the preadipocyte population. S-100 protein has been identified in various mammalian tissues and recently mature adipocytes have been shown to be positive for this protein. Because fibroblasts are negative for S-100 protein, the present study tested the S-100 immunoreactivity of preadipocytes by the peroxidase-antiperoxidase (PAP) preembedding method at the ultrastructural level both in vivo and in culture. Mature adipocytes and early preadipocytes, including fibroblast-like cells devoid of lipid droplets, were positive both in vivo and in culture. Endothelial cells and pericytes were negative; but flattened, lipid-free, fibroblast-like cells surrounding the pericytes were positive. True fibroblasts both in vivo and in culture were negative. Therefore, S-100 protein can be a useful biochemical marker in distinguishing fibroblasts from early preadipocytes.

Morphological identification of brown adipose tissue by magnetic resonance imaging in the rat

Morphological distinction between brown and white adipose tissue was obtained in the rat by MRI at 7 Tesla. Both superficial (subcutaneous) and deep (mediastinal) brown fat was visualized; the level of resolution was less than 1 mm. These results show that MRI is a potentially useful tool for studying the biology of brown adipose tissue in the experimental animal and, prospectively, in man.

Pachydermoperiostosis (primary hypertrophic osteoarthropathy): report of a case with evidence of endothelial and connective tissue involvement

A case of pachydermoperiostosis characterised by the presence of finger clubbing, periostosis, sweating of hands and feet is described. Modifications of capillaroscopic pattern and of arteriovenous anastomoses are reported. The periungual border and finger tip tissue showed diffuse endothelial hyperplasia, hyalinosis, and sclerosis with packing of collagen fibres. Electron microscopy showed hypertrophic and activated endothelia (numerous and hypertrophic Golgi complexes, several Weibel-Palade bodies, vesicles of micropinocytosis, and glycogen particles), the basal membrane thickened and reduplicated, perivasal infiltrate in superficial derma, reticulation and segmentary reduplication of basal membrane in arteriovenous shunt. In the perineural connective tissue numerous Luse bodies (long spacing collagen) were evident. The data indicate that in the early phase of pachydermoperiostosis morphological endothelial and collagen fibre abnormalities are present, though there is a normal peripheral blood flow.

Ultrastructure of pituitary folliculo-stellate cells of lactating rat during treatment with 2-bromo-alpha-ergocriptine

Folliculo-stellate cells of adenohypophysis were studied by transmission electron microscopy in lactating rats during treatment with the dopaminergic agonist 2-bromo-alpha-ergocriptine. Folliculo-stellate cells showed marked activation in control lactating rats, were unaffected by a single injection of the drug (3 mg/kg), regressed to the morphology of those found in non-lactating animals upon 6 days of drug treatment (1 mg/kg/die) both in presence and in absence of the suckling stimulus. However, morphometric analysis showed a proportion of folliculo-stellate cells in the gland which was similar in the four experimental groups (range: 11.3-13.5%), despite the increasing reduction of prolactin cells (55, 44, 32, 30%). In chronically treated animals to which suckling had been denied, extruding and degenerating prolactin cells were found, as well as extracellular material in non follicular spaces; the latter were lined by both folliculo-stellate and endocrine cells. These data suggest a dual reactivity of folliculo-stellate cells in the adenohypophysis according to the functional status of the gland.

Correlated ultrastructural and immunological findings in CD8+ and CD4+ peripheral T-cell lymphomas

Ultrastructural features of CD8+ and CD4+ peripheral T-cell lymphomas were studied and the results revealed distinct traits correlated with phenotype. CD8+ peripheral T-cell lymphomas were characterized by a rich organular pattern with a well-developed Golgi apparatus, dense granules, numerous and atypical giant mitochondria. CD4+ peripheral T-cell lymphomas were characterized by wide cytoplasmic areas devoid of organelles. Since similar ultrastructural features differentiated normal and pathological CD8+ and CD4+ peripheral T-lymphocytes, we conclude that under both normal and pathological conditions the expression on the part of the peripheral T-lymphocytes of CD8+ and CD4+ phenotypes is associated to morphological features which distinguish the two subsets.

Diabetic hand syndrome

Diabetic hand syndrome is a condition affecting about 30% of patients with insulin-requiring juvenile diabetes. Characteristic findings in this syndrome are mild- to- moderately severe joint contractures of the fingers, particularly at the proximal interphalangeal joints in the ring and small fingers, and thickening of the skin of the dorsum of the hand. There is no evidence of palmar fascial thickening or Dupuytren's contracture. Occasionally other joints may be involved, such as the wrists, elbows, hips, knees, and toes. In the case presented in this report light and electron microscopic studies showed that the disease presents aspects similar to those of other "fibrotic diseases" as described by Kisher and Speer. Surgical treatment was only partially beneficial in this patient.

Unresponsive enteropathy associated with circulating enterocyte autoantibodies in a boy with common variable hypogammaglobulinemia and type I diabetes

A 13-year-old boy with common variable hypogammaglobulinemia and type I diabetes developed a severe enteropathy that proved to be unresponsive to any treatment, including total parenteral nutrition. No evidence of known etiologies of malabsorption and/or secretory diarrhea was found in this subject. A high titer of complement-fixing enterocyte autoantibody was persistently found in the patient's serum. These features suggest that the enteropathy of this primarily immunodeficient subject had an autoimmune origin. A cycle of cyclophosphamide failed to show any amelioration of the diarrhea or a significant decrease in the autoantibody titer.

Marginal and folliculo-stellate cells of the pituitary gland of the rat. A comparative morphometric study in lactating animals

We examined non-granulated pituitary cells (folliculo-stellate cells and anterior and posterior marginal cells of the pituitary cleft) in lactating and virgin female rats by means of electron microscopy and morphometry. Ultrastructure and morphometric parameters of the cells lining the pituitary cleft were similar in the two groups of animals. On the contrary, folliculo-stellate cells showed a marked nucleocytoplasmic activation in lactating rats in the electron microscope, which was confirmed by morphometric measurements. These results are not consistent with the hypothesis that the three cell types share the same reactivity during pituitary hyperfunction and that they have a common function, as suggested by purely morphological studies in various endocrine conditions. We believe that quantitation of cell response during such stimuli could be useful to further elucidate this matter.

Evidence of immune deposits and of basement membrane alterations in dermal vessels of normal skin of patients with essential mixed cryoglobulinemia

To gain insight into the pathogenic mechanisms of immune complex-mediated vasculitis, clinically normal skin specimens from the forearms of 12 patients with essential mixed cryoglobulinemia were investigated by light microscopy, immunofluorescence microscopy, and electron microscopy. Basement membrane alterations were documented in 9 patients. Eleven patients had deposits in vessel walls, but only in 1 was there evidence of inflammation. The same immunoglobulins of the cryoproteins could be demonstrated in the tissue deposits by immunofluorescence analysis and by immunoelectron microscopy. These findings suggest that, in essential mixed cryoglobulinemia, immune reactants in dermal vessels of normal skin are more common than is evidenced by clinical examination. Moreover, it seems that cryoglobulins, as such, are not sufficient to trigger an inflammatory process: Additional local or plasma factors are required. Deposits were absent in 7 patients with cryoglobulinemia that was associated with a primary disorder. This could be ascribed to the lower cryocrit levels documented in this group of patients, or to the shorter duration of their disease.

Brown adipose tissue: a scanning electron microscopic study of tissue and cultured adipocytes

The ultrastructure of rat brown adipose tissue (BAT) and of adipocytes cultured from BAT were studied by scanning electron microscopy (SEM). Brown adipocytes in the intact tissue were arranged in lobules with bundles of collagen among them; within each lobule 20- to 40-microns-large adipocytes were packed together. Fibers of reticular collagen enveloped each adipocyte and also connected each cell to vessels and nerves. At the adipocyte surface rounded protrusions were present, which corresponded to the BAT-typical multivacuolar lipid depot. Gradual digestion of the stroma with collagenase disclosed a more delicate, felt-like cover surrounding each adipocyte, probably representing the external lamina of the cell. Complete digestion of the stroma showed a smooth plasmalemma with occasional roundish blebs which varied in size. Cultured (24 h) brown adipocytes from the stromal-vascular fraction of BAT were elongated or polygonal in shape, with a flattened, central nucleus and a number of spherical cytoplasmatic inclusions which have the same dimension and location as lipid droplets. These inclusions were arranged either at cellular poles or around the nucleus; this suggests that brown adipocytes with mature features were present in the culture. Pictures suggesting the detachment of lipid droplets from the cell body were also visible. Lipid droplet extrusion could be a complementary mechanism which might explain the rapid delipidation of brown adipocytes in culture.

Effects of noradrenaline exposure on rat brown adipocytes in cultures. An ultrastructural study

Adipocytes in intact brown adipose tissue show multivacuolar lipid deposit and mitochondria of 'typical' morphology. Cultured brown adipocytes retain the multivacuolar lipid deposit, while 'typical' mitochondria degenerate and 'atypical' organelles appear instead of the former. Since evidence exists that catecholamines deeply influence brown adipose tissue morphology and function in vivo, we undertook the present ultrastructural investigation to assess whether exposure of cultured brown fat cell to noradrenaline could prevent (or induce regression of) the in vitro morphological modifications of brown adipocytes. Brown adipocytes cultured for 8 h in the presence of noradrenaline (5 X 10(-5) M) had a larger mitochondrial area (i.e. a larger percentage of cytoplasm occupied by non-degenerating mitochondria) in comparison with control cells, as assessed by morphometry; this was due to larger number of mitochondria in noradrenaline-treated cells. Moreover, a number of cells with mitochondria strictly resembling those of the intact tissue were visible in noradrenaline-treated cultured after 8 hr, while 'typical' mitochondria were no longer observed in parallel control cultures. After 5 days of culture without hormone addition, exposure to noradrenaline (5 X 10(-5) M) did not induce quantitative modifications of 'atypical' mitochondria or changes of their ultrastructure up to 12 hr. However, reduction in size of the lipid deposit and activation of both rough endoplasmic reticulum and Golgi apparatus were evident in noradrenaline-treated adipocytes in comparison with non-treated cells.

Ultrastructural findings in the jejunal mucosa of children with IgA deficiency

The primary aim of this work was to investigate the ultrastructural morphology of the small intestinal mucosa in children affected by selective IgA deficiency (SIgAD). Absorptive tests and intestinal biopsies were performed in a group of nine children with SIgAD, none of them presenting with diarrhea. Biopsy specimens were processed for routine histology and scanning or transmission electron microscopy (SEM and TEM). By light microscopy, the jejunal mucosa appeared normal in all but one patient with patchy villous atrophy. By SEM, two further biopsies showed small areas of flat mucosa surrounded by villous ridges of nearly normal height. By TEM, four out of the nine mucosal specimens showed degenerative changes of the surface epithelium, including enlargement of the mitochondria, apical accumulation of primary and secondary lysosomes, and shortening and branching of the microvilli. These findings suggest that the small intestinal mucosa of children with SIgAD often shows pathological changes, some of which are recognizable only at the ultrastructural level. The study of biopsy specimens by SEM seems to be a useful diagnostic tool when patchy mucosal damage may occur, as in some of our patients with SIgAD.

Parathyroid glands in primary hyperparathyroidism: an ultrastructural study of 50 cases

Parathyroid glands from 50 cases of primary hyperparathyroidism were examined by light and electron microscopy in an attempt to elucidate the diagnostic role of electron microscopy in this disease. In the cases in which only one gland was removed at surgery, a final diagnosis by light microscopy was not possible. The electron microscopic findings for some of these single glands (e.g., ribosomal-lamellar complexes and groups of centrioles) suggested that they were adenomas. In cases in which two or more enlarged glands were removed, a correct final diagnosis could be made on the basis of the light microscopic findings alone, and electron microscopy provided no further significant information. Where one enlarged gland and one normally sized gland were removed, electron microscopy disclosed important findings in the normally sized glands. Specifically, light microscopic examination of normally sized glands suggested endocrine suppression, while electron microscopy showed chief cell activity, thereby changing the final diagnosis from adenoma to hyperplasia. The clinical follow-up assessment in some of these patients confirmed the electron microscopic findings. Therefore, the incidence of adenoma in patients with primary hyperparathyroidism should be critically re-evaluated by ultrastructural studies of the normal glands that should be removed with the enlarged ones.

Ultrastructure of brown adipocytes mitochondria in cell culture from explants

Brown adipocytes lose in culture their typical mitochondria, which are replaced by others of non typical morphology. During studies aimed at clarifying this phenomenon we found that better preservation of the 'typical' mitochondrial morphology is obtained in vitro after a long period of time, when cells from small fragments (explants) of brown adipose tissue (BAT) are cultured instead of collagenase-isolated brown adipocytes. These results suggest that the explant technique could be better suited to study brown adipocytes in culture than other methods employing collagenase-isolated cells.

Liposarcoma. An ultrastructural study of 15 cases

Fifteen liposarcomas from 13 patients were examined by electron microscopy. These included nine primary tumors, four recurrent tumors after primary surgery or irradiation, and two metastatic lesions. Twelve of the liposarcomas were located in the thigh, and 11 were of the myxoid variety. All neoplasms were composed of cells having the ultrastructural characteristics of some stage of lipoblastic differentiation, i.e., lipid droplets, micropinocytotic vesicles, glycogen, external lamina, intermediate filaments, Golgi apparatuses, rough and smooth endoplasmic reticulum, and mitochondria. The nuclear-cytoplasmic ratio and nuclear pleomorphism were related inversely to the size and number of lipid droplets. Lipoblasts were frequently in close association with capillaries and pericytes, and in four cases lipid droplets were found in pericytes. Multivacuolated, mitochondria-rich lipoblasts, resembling brown fat cells, also were seen. Most tumors contained lipid-free, poorly differentiated mesenchymal cells that showed a continuum of morphologic differentiation to cells that closely resembled early lipoblasts that contained nonmembrane-bound lipid vacuoles. Fibrolipoblasts, cells containing lipid droplets and abundant rough endoplasmic reticulum, were observed only in well-differentiated liposarcomas. Some soft tissue sarcomas contain vacuolated cells that simulate lipoblasts by light microscopy but prove to be reactive or malignant fibroblasts, histiocytes, or smooth muscle cells ultrastructurally. Therefore, use of electron microscopy may be necessary to establish the line of differentiation in these neoplasms.

Abnormalities in dermal vessel walls of normal skin of patients with essential mixed cryoglobulinemia. An ultrastructural study

Immune deposits have been detected in vessel walls of forearm normal skin of patients with essential mixed cryoglobulinemia. No inflammatory cells were present around the vessel walls. These findings suggest that simple deposition of immune complexes is not sufficient to trigger an inflammatory reaction.

Isolation and ultrastructural features of brown adipocytes in culture

Interscapular brown adipose tissue was removed from young rats, the cells isolated using collagenase, pelleted by centrifugation and cultured. Ultrastructural observations were made on these cells immediately after isolation and on Days 1, 2, 4, 10 and 14 of culture. The isolated cells show the typical submicroscopic features of cells in intact brown adipose tissue, i.e. a multivacuolar lipid depot and numerous typical mitochondria with dense cristae. However, as early as Day 1 of culture, the cells show degeneration of the typical mitochondria which are probably then extruded from the cells. Atypical mitochondria now begin to appear and become dominant on Day 4 of culture. By contrast, the typical multivacuolar shape of the lipid droplet does not change. Not even after prolonged periods of culture (2-4 weeks) is there any evidence of coalescence of the multivacuolar lipid depot. These findings are consistent with the possibility that the typical mitochondria of brown adipocytes depend on in vivo conditions, perhaps adrenergic innervation, while the multivacuolar characteristic of the lipid depot does not, and may be an intrinsic feature of the brown adipose cell.

An ultrastructural study of adipocyte precursors from epididymal fat pads of adult rats in culture

It has been demonstrated that cells with poor or no lipid content, isolated from epididymal fat pads of young rats, develop fully into mature adipocytes in vitro. The ultrastructural feature of these cells during such a development have been studied recently. In the present work the electron microscopic aspects of similarly obtained cells from adult rats have been investigated. It has been found that no morphological differences are present in the cells immediately after isolation between young and adult rats. During culture the cells from both adult and young rats show the same maturative process, but in adult rats this process is generally slower and not homogeneous, suggesting the presence of two populations of adipocyte precursors. The former accumulate lipids quickly and have electron microscopic features very similar to those observed for young rat precursors, however maturation is still faster in the latter cells. The latter have electron microscopic aspects of less differentiated cells (some fibroblast-like features) during the first days of culture; however they show a similar development when longer culture periods are studied. These data suggest that the fibroblast-like cells seen after a period of time in culture probably represent an early stage of adipocyte precursor differentiation. Thus it is suggested that in adult mammals, there may be a population of adipocyte precursors present within the adipose tissue which upon stimulation by as yet unknown factors would develop fully into adipocytes.

An ultrastructural morphometric analysis of the adenohypophysis of lactating rats

A morphometric analysis of the adenohypophysis (pars distalis) of lactating rats was carried out by a semi-automated method at the ultrastructural level. The cellular elements were identified by their ultrastructural morphology. The following values were considered for the morphometric study: numerical density of cells/mm3 of tissue and the percentage of parenchymal volume occupied by every cell type. Mammotropes (PRL cells) numbered 624 X 10(3)/mm3 and occupied 59.9% of the parenchymal volume (p.v.). Somatotropes (GH cells) numbered 206 X 10(3)/mm3 and occupied 15.0% of the p.v. Folliculo-stellate cells (FS cells) numbered 128 X 10(3)/mm3 and occupied 8.1% of the p.v. Gonadotropes (GN cells) numbered 47 X 10(3)/mm3 and occupied 6.0% of the p.v. Adrenocorticotropes (ACTH cells) numbered 45 X 10(3)/mm3 and occupied 3.8% of the p.v. Thyrotropes (TSH cells) numbered 36 X 10(3)/mm3 and occupied 3.4% of the p.v. PRL cells were characterized by aspects compatible with intense hormone production. GH cells did not show differences with those of nonlactating animals. Folliculo-stellate elements appeared hypertrophic with abundant cytoplasm, enlarged Golgi complex, and dilation of the follicular lumina. GN cells had abundant cytoplasm with a well-developed and dilated ergastoplasm, particularly in type II GN cells. ACTH cells did not show differences with those of nonlactating animals. TSH cells showed moderate nucleocytoplasmic activation. These fine structural morphometric findings are discussed in relation to other studies regarding nonlactating adenohypophysis and hormone changes during lactation.

Human brown adipose cells in culture

Brown adipose tissue (BAT), obtained from the axillary and perirenal regions of newborns 24-48 h after death, was digested with collagenase and the free cells were cultured. Only the cultures of cells from tissue obtained later than 24 h post mortem were successful. These cells grew slowly to reach confluence. Their typical mitochondria gradually disappeared, being replaced by untypical mitochondria. After confluence, the cells accumulated large amounts of lipid in non-coalescent multivacuolar depots. This model can be useful for the study of the metabolic and morphological features of human brown fat cells.

An ultrastructural study on muciparous microcysts of the human adenohypophysis

The microcysts found in two adenohypophyses removed from patients with nonsecreting adenomas of this gland have been studied. In one case the cysts were completely surrounded by neoplastic tissue, whereas in the second they were located within the normal parenchyma. The cysts were surrounded by a basement membrane, and appeared to contain a finely granular weakly electron-dense substance. Their walls were lined by mostly cubic cells with microvilli, joined by junctional complexes. Intracytoplasmic microlumina could be seen in some of these cells. Cells showing cilia with a 9 + 2 fibrillar pattern and cells with mucosecretory differentiation were also present. Furthermore endocrine cells were also found in the cyst-lining epithelium. The ultrastructural aspects of the cyst cells lead to reject the hypothesis that these are derived from folliculostellate cells. Besides, intermediate aspects between cyst cells and tumor cells were never visible. Therefore it seems likely that a relationship between adenoma and cyst cells does not exist and that cyst cells originate from remnants of Rathke's pouch with a ciliate or mucosecretory differentiation. The presence of endocrine cells in the cyst-lining epithelium deserves further study, for it seems to indicate that an endocrine differentiation may occur in the adult, too. To our knowledge this is the first ultrastructural study of these structures in adult human pituitary gland.

Changes in the structure of somato-sensitive neurons in cat following retrograde uptake of HRP

Neurons of cat cerebral cortex, area S1, labelled by retrograde transport of HRP, have been studied by electron microscopy; the animals were sacrificed 48 h after HRP injection. The cells studied are those in which the enzyme is found both in granular and in diffused form in the cytoplasm (diffuse-granular HRP neurons, DGN), or in diffused form in the cytoplasm (Golgi-like labelled neurons, GLN). The observations have shown that the certain recognition of DGN through electron microscopy, requires a comparison with a semithin section adjacent to the ultrathin section since the labelling granules are light-scattering in dark field. Instead the GLN are not light-scattering in dark field but are directly and unmistakably identifiable even by electron microscopy. The DGN are well preserved on the whole in all their organelles; the GLN show a highly damaged aspect in relation to both the Golgi apparatus and the smooth reticulum, to the cytoplasmic organelles and to the nucleus. Our hypothesis is that the latter neurons take on this appearance because of the combined action of: a) the peripheral mechanical lesions caused by the needle and b) the enormous amount of HRP that the cell is forced to take up (through these pathways) because of its lost integrity and because of the large quantity of marker around the axons. In conclusion intracellular HRP is identifiable by electron microscopy only when it is found in diffused form in the cytoplasm.

A morphological study of the adipocyte precursor

In order to attempt to characterize the adipocyte precursor cell in situ in developing adipose tissues from young rats, the light and electron microscopic characteristics were determined of cells in situ in these tissues, as well as in suspensions from the same tissues of cells liberated with collagenase subsequently developing to adipocytes in culture. The functional characteristics of adipose precursor cells at different stages of development in culture is known from previous work, and could therefore be added in parallel to the morphological characteristics. In order to allow comparison with fibroblasts from a site where adipocyte formation does not occur, lung-fibroblasts were also studied in parallel cultures. In culture, a rapidly dividing cell confluenced and reached full expression to adipocytes. This cell had morphological characteristics developing at the same time as early lipid accumulation making it easily distinguishable from a lung fibroblast in culture. A similar cell was found in abundance in the peripheral, non-developed part of the intact epididymal fat pad, here often surrounded by collagen. However, the early preadipocyte (without lipid droplets) and the adipoblast cannot be morphologically distinguished in situ from the fibroblast; therefore it cannot be excluded that fibroblasts and adipoblasts are the same cells in adipose tissue, possibly deriving from the pericyte.

Ultrastructural aspects of nailfold capillaries in a case of eosinophilic fasciitis

An ultrastructural study was made on the nailfold capillaries in an 18-year-old female with eosinophilic fasciitis. Scleroderma-like capillaroscopic lesions were visible at the sites where biopsy was performed. Light microscopy revealed ectasic capillaries at the apex of dermal papillae. Aspects of thickening and duplication of the epidermal basement membrane as well as an activation of endothelial cells were visualized at the ultrastructural level. These cells contained many virus-like tubulo-reticular inclusions, associated with cisternae of endoplasmic reticulum. Aspects of degeneration of nerve fibres and Schwann cells were also present. Large, homogeneously electron-dense deposits could be seen in the basement membrane at the dermo-epidermal junction. This study not only confirms previous observations on the microangiopathy in eosinophilic fasciitis, but also documents two new aspects: electron-dense deposits at the dermo-epidermal junction and tubulo-reticular inclusions within endothelial cells.

Electron microscopy applied to fine-needle aspiration. A report of six cases from various sites

The authors report the results obtained from the application of electron microscopy techniques to the cytology of fine-needle-aspirated samples of neoplastic lesions from various body sites. These results show that the tissue structure, which is usually lost during the squashing necessary for light microscopy cytology, is preserved when the samples are processed for ultrastructural analysis. Electron microscopy also allows a highly detailed study of the cell's inner structures. Thus, when this technique is applied, fine needle-aspirated samples can be regarded as actual microbiopsies. However, because of the high cost of ultrastructural techniques, we suggest that actual analysis be performed only in selected cases, whereas fixation and inclusion for electron microscopy could be done routinely.

Ultrastructural features of cultured mature adipocyte precursors from adipose tissue in multiple symmetric lipomatosis

The pathogenesis of multiple symmetric lipomatosis (MSL) is as yet unknown; however, some studies seem to indicate the neoplastic nature of this lesion. In this study we have examined the ultrastructural features of the adipocyte precursors of patients with MSL. The cells were isolated by collagenase, cultured, and then examined at the moment of their confluence in a monolayer. Their ultrastructural features were compared with those of cells of the abdominal subcutaneous adipose tissue taken from patients with nonsystemic, surgically treated illnesses. When examined immediately after isolation, the cells from normal tissue did not show significant differences from MSL cells. In culture, however, MSL grew more quickly into a monolayer and showed numerous nuclear pockets and cytoplasmic microfilaments, which were not seen in cells from normal tissue. These differences appear compatible with the neoplastic nature of the MSL adipocyte precursors.

The normal human parathyroid gland. A histochemical and ultrastructural study with particular reference to follicular structures

Bioptic specimens of 10 normal human parathyroid glands taken during thyroidectomies were studied both by light microscopy, using a histochemical technique, and electron microscopy. All the glands exhibited regions of different sizes in which follicles made up the tissue architecture. The follicles contained a homogeneous colloid-like substance. Our results seem to exclude the amyloid nature of the follicular content suggested by some Authors, though no further clarification as to its real make-up is provided. The cells lining the follicles belong to a type not as yet described in the normal human parathyroid. These cells appear to be large and clear and are also found in the non-follicular parenchyma. On the basis of their morphologic features we have classified the large clear cells as a particular, deviated stage of the actively secreting chief-cell. The origin and significance of the follicles are also discussed.

[Submicroscopic study of brown adipose tissue in young rats by the freeze-fracturing method]

The authors report the results of their ultrastructural study on the rat brown adipose tissue using the freeze-fracturing techniques. It is well known from transmission electron microscopy that lipid vacuoles of the brown adipose tissue cells are bound by a dense line corresponding to a structure as yet totally unknown. The results of the study using freeze-fracturing technics show that the morphology of lipid vacuoles surface is different from that of the typical unit membrane. The possibility is discussed that the particular aspect of the surface is due to the lypolysis induced by tissue fixation.

[Ultrastructural study of the stellate cells of the adenohypophysis in an ovariectomized woman]

We have studied at the E.M. the adenohypophysis removed from a woman who had undergone bilateral ovariectomy 4 months earlier because of a disseminated breast cancer. Our study has focused on the submicroscopic aspects of follicular-stellate cells, whose function has not yet been fully ascertained, though it is known from studies carried out on laboratory animals, that these cells are activated under conditions of stimulus to hyperactivity of one or more of the cell types of the adenohypothysis. In our material we have observed numerous follicular structures with variable amounts of colloid-like substance. Follicular-stellate cells limiting colloid-filled cavities showed many cytoplasmic organules with hypertrophic Golgi complex, intracytoplasmic lumina, interdigitations of the cytoplasmic membranes. These aspects are consistent with a condition of hyperactivity of follicular-stellate cells due to bilateral ovariectomy.

[A new model for the in vivo study of adipocyte precursors in the rat]

Periepidydimal fat pad of young rat shows, in the peripheral zone, areas with lobular aspect and areas with flattened aspect, surrounded by a mesothelial sheath. In adult rats the flattened areas are no longer observed. The ultrastructural study of the cells present in the flattened zones of the periepidydimal fat pad and the comparison with the same tissue of adult rats seems to indicate that the flattened areas in the peripheral zone of the periepidydimal fat pad of the young rat are a site where the adipocyte precursors can best be studied. Furthermore in the pericytes of the blood vessels wall, rare little lipid vacuoles can be seen: this is in accordance with the hypothesis proposed by other autøhors that the precursors of the adipocytes derive from pericytes.

Eosinophilic fasciitis: a mast cell disorder?

The rarity of eosinophilic fasciitis has so far prevented systematic investigations. Its etiology is still unknown and its nosographical position to be defined. We report here a further case whose distinctive features were: a gradual onset simultaneous with allergic bronchial asthma; the absence of eosinophils and presence of a high number of degranulating mast cells and Sezary-like cells in the inflamed fascia. The follow-up and a second biopsy suggested that early steroid treatment is advisable in these patients.

[An ultrastructural immunocytochemical study of secretory granules of an adenohypophyseal tumor]

The unlabeled antibody peroxidase-antiperoxidase complex technique was used to stain for electron microscopy the secretory granules of a pituitary tumor that had been surgically removed from a woman with high serum prolactin levels. Granules were stained using anti-human prolactin serum. The diameter of the secretory granules was smaller than that measured for the granules of prolactin producing cells in normal human pituitary glands. A shortened storage phase would explain the diameter reduction.

[Ultrastructural changes in the mammary gland of the lactating rat induced by treatment with bromocriptine]

The authors report the results of their ultrastructural study on the lactating mammary gland of the rat treated with bromocriptine. On the sixth day of treatment the mammary gland shows the same morphological features of the physiologically involuting mammary gland and the same morphological features of the mammary gland of the rat whose pups have been taken away. These results suggest that the pharmacologic treatment with bromocriptine induces a physiological involution of the lactating mammary gland in the rat and that the same drug abates the effect of the persisting suckling stimulus.

[Ultrastructural histochemical study of the mammary gland of the lactating rat]

The authors report the results of their ultrastructural study on the lactating mammary gland of the rat using Grimelius' silver stain, modified for electron microscopy. The granules of the gland proteic ésocrine secretion are positive to silver impregnation, both within the cytoplasm and in the alveolar lumen. These results are interesting since they suggest that Grimelius' stain positive structures, in the mammary gland, should not be necessarily interpreted as endocrine, at least in the rat.

RER-associated structure in parathyroid glands removed because of tertiary hyperparathyroidism

We have performed a submicroscopic analysis of the parathyroid glands removed from 2 patients with tertiary hyperparathyroidism. In both cases an RER-associated structure was found, which has never been described in normal or pathologic conditions in protein-secreting cells. This finding was present in only one of the glands of each patient. Their morphologic features are described. The significance of this structure is also discussed.

Human malignant diffuse mesothelioma: submicroscopic study on the epithelial component

A submicroscopic analysis of eight cases of malignant diffuse mesothelioma was performed. Unlike normal and hyperplastic mesothelium, well differentiated neoplastic cells were found to have a prominent RER and a conspicuous Golgi system. By using a postfixation in osmium ferrocyanide, an amorphous substance was observed in the extracellular space. These features may be related to the ability of malignant diffuse mesothelioma to produce large amounts of hyaluronic acid. The significance of groups of membrane bound dense bodies found in seven of eight cases examined is also discussed.