Ultrastructure of a virilizing ovarian Leydig-cell-tumor

Summary A case of virilizing ovarian hilus cell tumor (Leydig-cell tumor) in a 37 year old female was studied by light and electron microscopy. The ultrastructural features of this rare and almost allways benign tumor are compared with those reported in the literature and with findings in normal and neoplastic interstitial cells of the testis. Tubulovesicular hyperplasia and formation of whorl structures of the endoplasmatic reticulum together with the presence of exocytosis vesicles on the cell surface may be the morphological manifestation of endocrine activity of the tumor. The identity of ultrastructural and optical diffraction characteristics of the crystal inclusions in both cells (hilar and testicular interstitial) favours the assumption of an homology of both cells and their neoplasms.     

Malignant fibrous histiocytoma: an ultrastructural perspective

Malignant fibrous histiocytoma is a frequent diagnosis, but the relationship of the tumors to histologically similar soft tissue neoplasms is controversial. In this study, 157 examples representing the 4 main subtypes were reviewed by light microscopy and each tumor was studied with the electron microscope. Immunohistochemical stains were performed on 77 tumors. Electron micrographs on 100 fibrosarcomas were reviewed for comparison. Malignant fibrous histiocytomas often closely resemble fibrosarcomas at the ultrastructural level and differences between the two are generally of degree only. Evidence for true histiocytic differentiation was not found. The immunohistochemical results did not contradict the authors' impression from electron microscopy that malignant fibrous histiocytoma forms part of the histologic spectrum of tumors of fibroblasts.     

An electron microscopic and immunohistochemical study of Merkel cell carcinoma

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

Synaptic connectivity of serotonin graft efferents in the suprachiasmatic and supraoptic nuclei of the hypothalamus

We have previously reported that a cell suspension from the rostral part of the embryonic raphe grafted to the basal hypothalamus of 5,7-dihydroxytryptamine-denervated rats produced incomplete serotonin (5-HT) re-innervation of the suprachiasmatic nucleus (SCN) as opposed to hyper-innervation of the supraoptic nucleus (SON). We took advantage of this experimental model to investigate whether the graft-derived, 5-HT fibres retained normal ultrastructural features, and, particularly, a normal density of synaptic junctions, irrespective of the extent of target re-innervation. The intrinsic features of immunostained, graft-derived 5-HT axonal varicosities in both the SCN (ventral portion) and the SON were essentially similar to those exhibited by the respective endogenous innervation. Analysis of well-preserved varicosities in uninterrupted series of thin sections allowed us to evaluate directly the proportions of junctional to non-junctional 5-HT varicosities in both regions. Synaptic incidences were also remarkably conserved after grafting (45.5% in the SCN versus 38.5% in the SON; 48% and 38% in normal rats, respectively). Synapses were primarily reestablished on dendritic shafts, which also were identified as the major post-synaptic targets of the normal 5-HT innervations. We noted, however, a tendency toward increased numbers of symmetrical versus asymmetrical synapses in both the SCN and SON of grafted rats. Thus, irrespective of whether hypo-or hyper-innervation patterns developed post-grafting, the transplanted 5-HT neurons essentially retained normal ultrastructural features in their target territories, with a normal incidence of synaptic junctions. The data provide further support to the hypothesis that the innervation territory is the major determinant of the frequency with which ingrowing 5-HT fibres make synaptic junctions.     

Ultrastructural and biochemical studies on the intestinal absorption of a medium-chain triglyceride (MCT), tricaprylin

The intestinal absorption of a medium-chain triglyceride (MCT) was studied by electron microscopy and biochemical analysis. In jejunal absorptive cells of rats fed tricaprylin, the smooth endoplasmic reticulum in the apical cytoplasm appeared to increase in number and contained one or two particles about 40–80 nm in diameter that were less electron dense and similar in size and profile to very low density lipoprotein. Similar particles were also observed packed in the dilated Golgi sacs and in the extended intercellular spaces. These particles were remarkably increased in number as compared with those in fasted rats. Biochemical analysis of lymph from the main intestinal lymph duct showed that caprylate was apparently demonstrated only in the lymph of rats given tricaprylin at the maximum rate 3h after oral administration. The study strongly suggests that medium-chain triglyceride is at least in part transported via lacteal, possibly in the form of very low density lipoprotein.     

An electron microscopic study of glomerular lesions in hereditary nephrotic mice (ICGN strain)

Summary Glomerular lesions in hereditary nephrotic mice (ICGN strain) were investigated by electron microscopy. The glomeruli of unaffected animals, which appeared normal by light microscopy, had developed an ultrastructural change in the glomerular capillary basement membrane (GCBM). There was a partial thickening of the GCBM with bilaminar splitting of the lamina densa and an electron-dense fibrillar material exhibiting cross-striations. In affected animals, light microscopy revealed a marked thickening of GCBM and an increase of mesangial matrix without cellular proliferaton. By electron microscopy, multilaminar splitting of the lamina densa in the thickened GCBMs and fusion of the epithelial foot processes were observed. In some severely affected animals, immune complex deposition was found in GCBM, but little if any was observed in other animals. In the end, the glomeruli were globally sclerosed. Our findings suggest that initial structural abnormalities in GCBM may play an important role in the onset and development of the disease, though subsequent events such as immune complex deposition would modify the disease.     

An electron microscopic study of neurosecretion in the cerebral ganglion of the earthworm

Non-synaptic, exocytotic release of neurosecretory granules in cerebral ganglion neurons was observed electron microscopically in 3 species of the oligochaete annelids Aporrectodea caliginosa, Octolasion cyaneum and Lumbricus terrestris. In addition to the features indicating exocytotic release of neurosecretory granules into perineuronal space, possible features of neurosecretion into blood vessels were seen within the cerebral ganglion. Axon terminals in synaptic contact with perikaryal profiles of cerebral ganglion neurons were also found.     

AN ELECTRON MICROSCOPIC EXAMINATION OF AGE-RELATED CHANGES IN THE RAT LIVER. The Influence of Diet

The influence of age and diet on the ultrastructure of hepatocytes is reported. The following dietary manipulations were investigated: Group 1, fed ad libitum a diet containing 21% protein; Group 2, fed a similar diet but restricted to 60% of the intake of Group 1 from 6 weeks of age onwards; Group 3, restricted from 6 weeks to 6 months of age and thereafter fed ad libitum; Group 4, restriction started at 6 months of age; Group 5, fed ad libitum a diet containing 12.6% protein. In all groups the size of hepatocytes was found not to increase during adult life. The size of hepatocytes in Groups 2 and 4 was the same as or larger than that of the other groups; thus food restriction resulted in a decreased number of hepatocytes. Changes in the structure of some organelles and the accumulation of lipofuscin granules occurred with advancing age and the extent of these age-related changes was less in Groups 2 and 4 than in the other groups. These morphologic findings in conjunction with our previously reported metabolic findings provide a new view of the action of food restriction on the aging process. ACTA PATHOL JPN 38: 1119∼1130, 1988.     

Structural and replicative forms of mitochondrial DNA in tissues from adult and senescent BALB/c mice and Fischer 344 rats

Age-related changes in the structure and replication of mitochondrial DNA (mtDNA) were investigated in different organs from young adult (9–10 months' old) and senescent (28–29 months' old) BALB/c mice and Fischer 344 rats. Total mtDNA from brain, heart, kidney and liver was isolated by centrifugation in ethidium bromide—CsCl gradient and examined for the occurrence of complex forms and replicative intermediates by electron microscopy. The frequency of catenated mtDNA (interlinked molecules containing two or more circular units) varied from about 2.5% to 5% in adult tissues and showed a small increase in the majority of senescent organs. The frequency of double-sized circular molecules, or circular dimers, was very low in adult tissues, with an average of about 0.04% in mice and 0.1% in rats. The frequency of circular dimers increased with aging to 1.9% in mouse brain and 1.5% in rat kidney, with smaller increases (0.4% and 0.7%) in heart mtDNA from both species; there was no significant increase in the other organs. It is suggested that the increase in the frequency of circular dimer mtDNA reflects an overall deterioration of tissue physiology rather than intrinsic senescent changes in the mitochondria. The frequencies and types of the various replicative forms of mtDNA varied significantly according to tissue but not according to species or donor age. The only exception was a significant increase in the frequency of larger replicative forms in senescent mouse liver, to about 20% compared with 12% in adult liver, suggesting an age-related change in the rate of mtDNA replication and/or turnover in this organ.     

Elektronenmikroskopische Befunde an inneren Organen bei Morbus Fabry

Zusammenfassung Es werden elektronenmikroskopische Beobachtungen zur Lokalisation und zur Feinstruktur der Glykolipideinschlüsse in verschiedenen inneren Organen bei Morbus Fabry berichtet. Die intrazellulÄren und extrazellulÄren Einschlüsse bestehen aus vielschichtig lamellÄren Membransystemen in konzentrischer und exzentrischer sowie in stapeiförmiger paralleler Anordnung. Diese lamellÄre Anordnung ist charakteristisch für flüssigkristalline Phasen von Phospholipid-Wasser-Systemen. Erstmalig werden ultrastrukturelle Befunde an den inneren Organen einer erkrankten Frau mitgeteilt. Demzufolge lassen sich bei heterozygoten Frauen gleiche Glykolipidablagerungen wie bei homozygoten MÄnnern nachweisen. Die Beziehung der Glykolipideinschlüsse zu den Lysosomen wird erörtert.

---

Electron microscopic observations in internal organs in morbus fabry

Summary Electron microscopic findings are reported on the localization and fine structure of glycolipid inclusions in different organs (heart, kidney, lymph nodes, arterial blood vessels, pancreas) in Fabry's disease in a female. The intracellular and extracellular inclusions were made up of multilamellar membraneous systems in concentric, excentric, and parallel arrangement. This fine structure is characteristic of liquid-crystalline phases of phospholipid-water systems.The same type of inclusions are found in the internal organs of heterozygotic women as in homozygotic men. The relationship between the glycolipid inclusions and the lysosomes is discussed.

Herrn Prof. Dr. F. Bolck, Direktor des Pathologischen Instituts der Friedrich-Schiller-UniversitÄt Jena, zum 60. Geburtstag gewidmet.