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F Giannessi

Publications and source records attributed to F Giannessi.

At least 37 records · Page 2Linked to original sources
PubMed1991

Comparative activity of doxorubicin and its major metabolite, doxorubicinol, on V79/AP4 fibroblasts: a morphofunctional study.

Doxorubicin (DXR), an anthracycline antineoplastic drug, is mainly metabolized to the C-13 dihydroderivative doxorubicinol (DXR-ol), which displays cytotoxic activity on various cell lines. To better characterize the cytotoxic activity of this metabolite, we have studied the effect of DXR (0.1-10 micrograms/ml) or DXR-ol (1-100 micrograms/ml) on the transformed fibroblast cell line V79/AP4 by means of the clonogenic assay, cytofluorescence, and light and electron microscopy. Both DXR and DXR-ol displayed a dose-dependent inhibition of colony formation with an IC50 factor DXR-ol/DXR of 19.5. A striking nuclear fluorescence was observed after DXR but not after DXR-ol. A low number of mitoses and a decrease in nucleoli staining affinity were the most evident alterations induced by DXR. Electron microscopy showed both nuclear and cytoplasmic changes in DXR treated cells: nucleolar segregation, cytoplasmic vacuoles, and mitochondrial swelling with dense needle-shaped material were observed. Exposure to formic acid confirmed the calcific nature of the mitochondrial bodies. Only the highest dose of DXR-ol brought about nuclear and cytoplasmic ultrastructural changes similar to those induced by DXR. Our data describe new in vitro findings on the cytotoxicity and morphological alterations induced by both DXR and DXR-ol, with a lower activity of DXR-ol against V79/AP4 fibroblasts.

Animals↗
PubMed1991

[Tubular structures revealed using tannic acid on the surface of the epithelium of the tympanic cavity of the chicken].

We have studied the ultrastructure of the epithelium lining the tympanic cavity of chicken, using two embedding techniques. In certain cases, the epithelium was minced in Karnovsky fixative, post-fixed in osmium, dehydrated and embedded in Epon, following the usual methods. No morphologically detectable structures were seen at the level of the epithelium surface. In other cases, the epithelium was immersed in Karnovsky fixative and subsequently in glutaraldehyde (1%) to which, however, tannic acid (1%) was added; the specimens were then osmicated, dehydrated with Epon and embedded in polar Epon mix. This method was sometimes used to study the alveolar surfactant, since this makes it possible to preserve its phospholipid fraction. The epithelium, in this way, is seen to be covered by an electron-dense material made up of thin, intertwined tubules. The hypothesis formulated is that the tubules are related to the presence of surfactant substances.

Animals↗
PubMed1990

In vitro morphological characterization of the bursal reticuloepithelial (REp) cells of chicken.

The REp cells of the bursa follicle medulla of chicken were isolated in vitro. Culture of the REp cells was maintained over a period of 10 days and the cells were observed at 3 and 10 days by means of transmission electron microscopy (TEM) and immunofluorescence. The use of an anticytokeratin monoclonal antibody confirmed their epithelial nature. TEM observations showed the presence of desmosomes and tonofilaments, which are characteristic of epithelial cells. Furthermore, to some extent the cells regenerated in vitro the network they form in vivo. Though the growth rate becomes slower with time, the features of the REp cells do not significantly change.

Animals↗
PubMed1990

Reappraisal of histogenesis in the bursal lymphoid follicle of the chicken.

The development of the bursal follicle and the appearance of the follicle-associated epithelial (FAE) cell and the reticuloepithelial (REp) cell were studied. The stages of development of the bursal follicle were observed by light and electron microscopy; an anticytokeratin monoclonal antibody was also used. At the beginning of follicle development, a mesenchymal cell cluster is observed in the tunica propria; the cluster becomes wedged in a niche of the surface epithelium, and gradually it is completely surrounded by the epithelium itself, which closes under the clump of mesenchymal cells. The epithelial cells lying upon the mesenchymal clump become necrotic, and a number of mesenchymal cells bulge out, forming the FAE cells. The epithelial cells that have closed under the mesenchymal nodule become stratified and form the REp cells; they become star-shaped because the medullary-lymphoid cells grow between them. Finally, the cortex is formed, possibly as a result of the migration of medullary cells before they peripheralize. It is concluded that FAE cells are not specialized epithelial cells, as they do not react to an anticytokeratin monoclonal antibody; on the contrary, they are formed by mesenchymal stemcells that bulge into the lumen and change their character after moving into the epithelium. The REp cells appear in the follicular primordium shortly after the bursal follicle begins to develop; the pronounced reactivity of the REp cells to an anticytokeratin monoclonal antibody supports the hypothesis of their epithelial origin.

Age Factors↗
PubMed1990

Lympho-epithelial interactions in the turtle Chrysemys scrypta elegans.

The morphological relationships present in the areas of lymphoid infiltration found in the esophagus in Chrysemys scripta elegans were studied by the use of light and transmission electron microscopy. These infiltrations are widespread and can be observed in the lamina propria and the covering epithelium. Electron microscopy reveals the presence of epithelial cells with differing characteristics at the apex of the lymphoid infiltrations. The introduction of horseradish peroxidase (HRP) into the esophageal lumen revealed that these cells possess a micropinocytotic activity. On the basis of the morphological and experimental results obtained, a hypothesis is advanced of the existence, also in the turtle, of a local system of uptake of extraneous material, which induces local and systemic immunological processes.

Administration, Oral↗
PubMed1990

Ultrastructural and immunocytochemical study on bursal follicle medulla cells in Gallus domesticus.

The use of the monoclonal anti-cytokeratin 6 and 18 antibody Dako CK 1 revealed a marked positivity of reticulo-epithelial cells (REp). Aspecific esterase testing, light microscopy, and electron microscopy were used in order to obtain a comparison between the morphology of the lymphoid follicle medulla and the picture obtained by using the monoclonal antibody CK 1. Results showed that the bursal follicle medulla can be divided into 2 areas: an esterase-positive, cytokeratin-negative centre-medulla, and a more peripheral cytokeratin-positive, esterase-negative area. These 2 regions appear to be separated by a boundary composed of flattened REp cells. Desmosomes were also observed not only among their processes, but also between the latter and the side of the cortico-medullar boundary epithelium which is external with respect to the basal membrane.

Animals↗
PubMed1990

Ultrastructure of the supporting cells of the paratympanic organ in the chicken: a preliminary study.

Electron microscopic studies reveal that the supporting cells of the paratympanic organ in the chicken have a fine structure characterised by mitochondria, RER and a well developed Golgi apparatus; furthermore, several vesicles with a clear content can be observed in the apical cytoplasm. The ultrastructure of supporting cells indicates high metabolic activity. The possible metabolic and mechanical function of the supporting cells are discussed.

Animals↗
PubMed1989

On the presence of reciprocal synapses in the paratympanic organ of the chicken.

The innervation pattern of the paratympanic organ was studied by TEM. The paraympanic organ is a small tapering vesicle, typical of birds, situated in the medial wall of the tympanic cavity; it contains hair cells which are similar to type II receptors of the acoustic-lateral system; these cells are characterised by synapses which are not only afferent and efferent, as previously described, but also reciprocal with efferent fibers. Our observation revealed some efferent nerve fibers which form a relationship with hair cells containing synaptic bodies situated next to the plasma membrane and near the fibers themselves. Since synaptic bodies are commonly considered to be the site where the transmission of the impulse from the receptor to the nerve fiber takes place, our pictures suggest that the efferent fibers and hair cells may be either presynaptic or postsynaptic with respect to each other in the paratympanic organ. The hypothesis is formulated that reciprocal synapses allow interaction between hair cells, thus determining an increase in the contrast of information sent by the paratympanic organ to the CNS.

Animals↗
PubMed1988

Distribution of esterase activity at the level of the epithelium of the diffusely infiltrated area (DIA) and of the cloaca in the Gallus domesticus: an ultrastructural study.

Esterase activity studies on the areas of lymphoid infiltration in the bursa of Fabricius (diffusely infiltrated area) and the dorsal wall of the cloaca showed that the epithelial cells exhibit varying degrees of diffuse esterase activity; it was possible to demonstrate the presence of spot-like esterase positivity in star-shaped cells in the epithelium itself. These cells can be found at various levels from the proximal to the distal region and have also been observed in the connective tissue of the tunica propria; as a result, the hypothesis has been advanced that they are connective tissue.

Animals↗
PubMed1986

The ultrastructure of the paratympanic organ in the domestic fowl (Gallus gallus domesticus).

The structure of the paratympanic organ in chickens was investigated by means of the transmission electron microscope. The epithelium lining the lumen of the paratympanic organ consists of sensory and non-sensory components. The sensory epithelium is composed of supporting and hair cells. The hair cells are similar to the type II receptor cells present in the neuroepithelia of the vestibule and of the lateral line organs. The afferent synapses at the bases of the hair cells are also described. The non-sensory epithelium is made up of cells with a clear cytoplasm and arranged in a single layer. It also contains dark, flattened cells which sometimes possess motile cilia. Special emphasis is given to the fact that the results agree with Vitali's theory that the paratympanic organ and the lateral line organs are homologous. It is concluded, therefore, that present knowledge about this structure is not yet sufficient to allow a definitive functional interpretation.

Animals↗
PubMed1986

A contribution to the study of the histogenesis of the bursal lymphoid follicles in Gallus domesticus.

Numerous investigators have shown that the development of the bursal lymphoid follicle in chicken begins with the formation of epithelial gemmations called epithelial buds. The mesenchymal stem cells migrate into these epithelial buds and give rise to the lymphoid cells of the follicle medulla. However, research carried out in our laboratory, using the semi-thin serial section technique and the electron microscope, leads us to think that the early stages of the development of the bursal lymphoid follicle might take place in the following way: the stem cells migrate towards the proximal surface of the lining epithelium where they collect in an invagination. These cells gradually increase in number and a cellular mass is formed which, therefore, does not grow in the epithelial framework but under it. The epithelial invagination near the mesenchymal mass becomes more and more pronounced, making the epithelium progressively thinner until it is finally necrotized. At this point, the cells of the mesenchymal anlage protrude into the bursal lumen.

Animals↗
PubMed1984

[The ultrastructure of the paratympanic organ (Vitali) in Gallus domesticus: preliminary studies].

The sensory epithelium of the paratypanic organ (Vitali) was studied by means of the electron microscope. Two kinds of cells are present. One type extends from the basement membrane to the surface of the epithelium; their nuclei are arranged close to the connective tissue and are surrounded by a pale cytoplasm. The distal part of these cells, which are denser and richer in organelles, possess microvilli. The cells of the second type are located above the basement membrane and are found between the upper parts of the cells of the first type. Their cytoplasm is rich in small round vesicles, free ribosomes and cisternae of rough endoplasmic reticulum are present especially in the infranuclear zone. The apical part contains a Golgi apparatus lysosomes and multive sicular bodies. At the apex each cell possesses a cuticular plate numerous stereocilia and one kinocilium. The stereocilia become increasingly longer from one side of the cell surface to the other and the kinocilium is situated on the side where the stereocilia are longest. Nervous fibers are present in the epithelium and are in close contact with the cells of the second type. The cells we have described are remarkably similar to the supporting and hair cells of the vestibular sensory epithelium.

Animals↗
PubMed1984

Morphological and histochemical study on the adrenal cortex of the dexamethasone-treated albino rat.

Morphological and histochemical examinations of the changes induced in the adrenal cortex by the administration of Dexamethasone (Decadron phosphate) to rats for 14 consecutive days were made at intervals during a 28-day post-treatment period, in order to follow the histo-functional recovery of this gland from the changes induced. The modifications that had occurred by the end of the treatment consisted of a decrease in the width of the zona fasciculata and the zona reticularis, an increase in the lipidic content, and degenerative mitochondrial signs in the zona glomerularis. Seven days after discontinuing treatment, we observed the disappearance of the zona intermedia, which reappeared on the 14th day after treatment. From this day on, the adrenal gland tended progressively to complete recovery. Dexamethasone therefore produces both short-term and long-term morphological and histochemical changes in all the adrenocortical zonae.

Adrenal Cortex↗
PubMed1984

On the role of the lymphoid follicle-associated areas in the organization of the bursal follicle in the cloacal bursa in birds.

The present paper contains data on the morphological modifications present in chicks which, after treatment with testosterone lasting 10 days (from the seventh to the seventeenth days after hatching), were killed on the 30th, 35th, 40th, 50th and 70th day of life; this interval of time might theoretically have allowed a gradual re-establishment of the bursal architecture. Examination of the bursae of Fabricus of the animals treated showed greatly varying pictures. The 2 main types of behaviour were the following: the histological pattern of certain bursae had been completely restored to normal. Others did not act in the same way but wide areas of their plicae proved to be devoid of lymphoid tissue and well-formed lymphoid follicles were observed only in certain places. These 2 kinds of behaviour, and particularly what we observed in the second case, might suggest that, since the lymphoid follicle-associated epithelial cells are the last to disappear after treatment with testosterone propionate and the follicles are restored only where these cells remain, the lymphoid follicle-associated epithelial cells may be considered to be responsible for the re-establishment of the bursal follicle.

Animals↗
PubMed1983

Ultrastructural aspects of the lymphoid follicle-associated cells of the cloacal bursa after treatment with silica or carrageenan.

The present paper describes the ultrastructural changes in the follicle-associated epithelial cells of the cloacal bursae, which were observed after treating chickens with silica or with carrageenan. These substances, which are widely known to be toxic to macrophages, were used to establish whether the behaviour of the follicle-associated epithelial cells is the same as that of the lining epithelial cells, which are not affected by the action of silica and carrageenan, or whether the follicle-associated epithelial cells behave in the same way as macrophages. Experiments showed that silica and carrageenan cause extensive damage to the structure of the follicle-associated epithelial cells. The results, especially those obtained with the endobursal administration of silica, would seem strongly to support the hypothesis that follicle-associated epithelial cells are of mesenchymal origin, because silica is selectively toxic for mesenchymal cells with histiocytic activity.

Animals↗