Acute eosinophilic leukemia. An ultrastructural study.

Observations on a 32 year old male are described. Hematological examination demonstrated leukocytosis with circulating blastosis and dystrophic hypereosinophilia of the blood and bone marrow, with cells at various stages of maturation. Cytotoxic chemotherapy led to complete remission for 5 months followed by a terminal relapse. No features in favor of an "eosinophilic collagenosis" were revealed at autopsy. Repetitive ultrastructural studies performed during evolution of the illness demonstrated considerable anomalies of the eosinophil line. The present observation thus shows the clinical, evolutional, cytological and autopsy criteria of an acute eosinophilic leukemia.     

Early contacts between fibroblasts. An ultrastructural study

Pairs of chick heart fibroblasts have been studied with the light microscope and then fixed in situ for electron microscopy at varying times after they have been seen to make contact with each other. The resultant electron micrographs show that areas of specialisation begin to develop within 20 sec of the contact being made. These specialisations resemble those seen in isolated chick heart fibroblasts where the cell comes close to the substrate and are thought to be areas of adhesion. The development of these areas and their associated microfilaments is described and an attempt is made to correlate this with the stages of the contact inhibition phenomenon.     

Penile Lentiginosis. An Ultrastructural Study

This study on five patients has revealed more extensive alterations to melanocytes than previously reported, and emphasizes the fact that depigmentation is an essential element of the condition. In hyperpigmented areas, melanocytes were increased in number along the basal layer of the epithelium, were hyperactive, and in some cases contained bizarre melanosomes. In two cases there was suggestion of a defect in melanosome transfer to keratinocytes. Lymphocytes were closely apposed to melanocytes, and, in hypopigmented areas, were clearly involved in their disintegration. In depigmented areas, there was complete absence of melanocytes and of melanosomes in keratinocytes, and lymphocytes were present in the basal layer. In general, the appearances did not resemble melanoma in situ with spontaneous regression, although a second biopsy of one patient after one year did reveal features of melanocytes suggestive of an early stage of this condition. The study has provided no clear information as to the initial cause of the condition, but the manner of destruction of melanocytes suggests an immune reaction. Neither has it been of assistance in suggesting a more precise name for it.     

Sympathetic ganglia in diabetes. An ultrastructural and stereologic study

An ultrastructural and stereologic study was performed on sympathetic ganglia collected at surgery from eight diabetic patients, seven age-matched non-diabetics and six subjects with glucose intolerance. All patients underwent surgery because of arteriosclerosis obliterans. Volume density (Vv) and mean thickness (tau) of the satellite cell layer were found to be significantly higher in diabetics (P less than .001 and P less than .002, respectively) than in the other two groups, between which no difference was found. Vv and tau of the endothelial basal lamina were found to be increased in the diabetic and glucose-intolerance groups at a low level of significance (P less than .05). Satellite cells are thought to exhibit a close similarity to Schwann cells. Ultrastructurally, cytoplasmic edema, increase of subcellular organelles and lipid inclusions were consistently observed in satellite cells from diabetic patients. The results suggest that there may be a metabolic impairment of these cells in diabetes.     

Hyperplastic cellular components of a hemangiopericytoma. An ultrastructural study

Based on ultrastructural features of cellular components of a hemangiopericytoma, hyperplastic cells are classifiable into fibroblast-like (group I), endotheloid (group II) and pericyte-like (group III) cells. The transformation of the group I cells to the group II, or to the group III cells, is pronounced in our electron micrographs and this may imply that the group I cell is the principal cell of origin in this neoplasm. The smooth muscle-like (group IV) cells comprising the media of the arteries and veins in this neoplasm may represent modified, possibly de-differentiated smooth muscle cells reacted to the neoplastic proliferation of the surrounding adventitial (group I) cells.     

Ito cells in lysosomal storage disorders. An ultrastructural study

An ultrastructural study was performed in a series of liver biopsies from patients with various lysosomal storage diseases to evaluate the extent of lysosomal hypertrophy and hyperplasia in Ito cells (ICs). In previous studies this has been considered to be absent or only rudimentary. Lysosomal storage was recognized by the presence of storage cytosomes surrounded by limiting membranes and by the appearance of their content which was identical to that in other hepatic storage lysosomes. Storage was found in sphingomyelinase deficiency (Niemann-Pick disease types A, B), in Wolman's disease, GM1 gangliosidosis, mucopolysaccharidosis and in multiple sulphatase deficiency. In type C Niemann-Pick disease it was virtually absent with the exception of cases with prominent hepatic symptomatology. Storage was of variable degree and was accompanied by a decrease in the physiological fat content (cytoplasmic lipid droplets). The degree to which ICs were affected correlated only with the extent to which nonspecific fibroblasts were involved in the specimens studied and thus seems to reflect storage in the fibroblastic population.     

Adrenomedullary chromaffin cells of the rat. An ultrastructural study

Adrenomedullary chromaffin cells of the rat were studied at the ultrastructural level. Chromaffin cells contained a large population of electron-dense-core vesicles of two types, one very electron-dense (norepinephrine) and the other moderately electron-dense (epinephrine). The vesicles showed an even distribution pattern in the cytoplasmic matrix. No physical contacts were observed between cytoplasmic and vesicle membranes to indicate exocytosis, a mechanism frequently observed in the hamster. For chromaffin cells to be used as a transplantable source of dopamine, both the cells and vesicles must survive the trauma of denervation and vascular elimination or alternatively acquire the two factors from the transplantation site.     

Immunoperoxidase localization of fibronectin during odontoblast differentiation. An ultrastructural study

Immunoperoxidase labeling of fibronectin in one-day-old mouse first lower molars allowed to visualize a striking redistribution of this glycoprotein during terminal cytodifferentiation of odontoblasts. The modifications involved both extracellular and cell surface localizations. The possible roles of these modifications in terminal differentiation of odontoblasts are discussed.     

Immunocompetent cells in the starfish Asterias rubens. An ultrastructural study

Cells from the axial organ of the starfish Asterias rubens were fractionated into two populations, adherent and non-adherent to nylon wool. In both populations the ultrastructural study revealed the presence of cells resembling the lymphocytes of the vertebrates, as well as phagocytic, peroxidase positive cells. The lymphocyte-like cells in the non-adherent population (average diameter 4 mu) have a high nucleo-cytoplasmatic ratio and are morphologically similar to Th lymphocytes while the adherent cells (average diameter 5.5 mu) are more similar to Bm lymphocytes. These observations are in line with the hypothesis that there exist, in the starfish, a primitive immune system with characteristics resembling those of the immune system of vertebrates.     

Unusual nuclear inclusions in four nerve biopsies. An ultrastructural study

The authors have reported four cases where the study of peripheral nerve biopsy revealed the presence of abnormal cells in the endoneurial space. Their bulky nuclei contain in fact numerous deposits more or less tubular reminiscent of the intranuclear structures observed in the multiple sclerosis brains, and other very rare diseases. Exceptionally it seems have these images been described in peripheral nerves. It must be stressed that only one patient had an inflammatory type disease. The meaning of these images is discussed, though no definite conclusion could be reached.     

An ultrastructural study of pyrenoids inLeptosiropsis torulosa

Summary The ultrastructure of the mature pyrenoid of the chaetophoracean algaLeptosiropsis torulosa is unlike any described for the green algae. The nucleus is surrounded by the pyrenoid, with only the endoplasmic reticulum interrupting the encircling pyrenoid. The pyrenoid possesses only the appressed plastid membranes that are in contact with the nucleus, with no traversing thylakoids present.     

An ultrastructural study of pale eumycetoma grains

The electron microscopic appearances of grains from seven patients with pale grain eumycetoma infections have been studied. The infecting fungi were Pseudallescheria boydii (2), Fusarium sp. (1), Acremonium kiliense (1), a non-sporing mould (2) and Trichophyton violaceum (1). P. boydii grown in vitro and grains from a Madurella mycetomatis infection were used for comparison. The most important ultrastructural features of the pale eumycetoma grains were the gross thickening of the fungal cell walls maximal at the periphery of the grain, the predominance of grossly disorganised hyphae and the appearance of cytoplasmic membrane systems. In some areas adjacent cell walls appeared to fuse. These changes may account for some of the well recognised difficulties in isolating organisms from eumycetoma grains and treating the infections with antifungal drugs.     

The morphogenesis of the human Paneth cell. An immunocytochemical ultrastructural study

In human duodenal mucosa Paneth cells originate away from the base of crypts and migrate towards the base during maturation. The earliest cells in the Paneth cell lineage could be identified by labelling of lysozyme in the Golgi apparatus. Specific labelling for lysozyme was present in the rough endoplasmic reticulum, Golgi apparatus, condensing vacuoles, granules and many lysosomes of mature Paneth cells. The maturation of the Paneth cell is accompanied by an increase in the content of lysozyme in the secretory granules and with senescence lysozyme diffuses into the cytoplasm.     

An ultrastructural study of connective tissue in mollusc integument III. Cephalopoda

We studied structure and ultrastructure of the subepidermal connective tissue (SEC) of the integument of three cephalopods (Sepia officinalis, Octopus vulgaris and Loligo pealii). In all species, three distinct regions of the SEC were recognised: (a) an outer zone (OZ) that included the dermal-epidermal junction, and consisted of a thin layer of connective tissue containing muscles, (b) an extensive middle zone (MZ) containing a compact network of collagen fibres and numerous cells, (c) an inner zone (IZ) of loose connective tissue that merged with muscular fascia. This arrangement differs from that in bivalves and gastropods and recalls vertebrate integument. The dermal-epidermal junction of cephalopods differed from that of bivalves, gastropods and mammals in that the epidermal cells did not possess hemidesmosomes, and their intermediate filaments terminated directly in the plasmamembrane. The thick (120-500 nm) basal membrane (BM) had a superficial zone containing a regular array of granules; a lamina densa composed of a compact network of small filaments and granules; and an IZ distinguished by expansions of granular material protruding into underlying structures. Collagen fibres contained fibroblast-derived cytoplasmic thread, running through their centres and were surrounded by granular material that joins them to adjacent fibres. The collagen fibrils were of medium diameter (30-80 nm) had the typical ultrastructure of fibrillar collagens, and were surrounded by abundant interfibrillar material. The hypodermis was loose, with a network of small bundles of collagen fibrils. Cephalopod integument appears to represent a major evolutionary step distinguishing this class of molluscs.     

Interaction of positively charged liposomes with erythrocyte membrane. An ultrastructural study

Structural perturbations of positively charged sonicated liposomes (L) induced by incubation with human erythrocytes have been studied by thin-section electron microscopy. It has been found that just after mixing with cells L bind to cell surfaces and fuse with each other, first forming larger L and then flattened multilamellar structures. Successive fusion events occurring in the latter result in a reduced number of bilayers which gradually comes to a single one.