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A Dolfi

Publications and source records attributed to A Dolfi.

At least 37 records · Page 2Linked to original sources
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

Questioning the role of adenosine deaminase in the development of B lymphocytes in chicken bursa.

Adenosine deaminase, a purine metabolic enzyme, was studied in lymphoid tissues of the developing chicken in order to evaluate whether enzyme activity is related to development of the immune system in birds in the same way as for mammals, in which adenosine deaminase is essential for lymphocyte differentiation, especially for the T-cell lineage. Enzyme activity was assayed in thymocytes and bursal lymphocytes at different times during chicken development ranging from the 17th day of embryonic life up to the 50th day after hatching. Adenosine deaminase activity was significantly higher in the bursa than in the thymus, regardless of whether such an activity was expressed per mg protein or per 10(8) cells; moreover, no substantial difference in the relative levels of adenosine deaminase was observed in thymocytes at the various stages of thymus development studied. Significant changes in enzyme activity, however, were found in bursal lymphocytes in which different amounts of adenosine deaminase appeared to be related to definite stages of bursal development and to specific immunological responsiveness of B lymphocytes to intravenously injected antigens. Therefore, if adenosine deaminase does play a role in the functional maturation of the immune system in birds, such a role appears to be related to the differentiation of the B- rather than the T-cell lineage.

Adenosine Deaminase↗
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↗
PubMed1989

The significance of intestinal flow in the maturing of B lymphocytes and the chicken antibody response.

The aim of the present study was to evaluate the influence of intestinal material on the maturing of B lymphocytes in the bursa of Fabricius and on the antibody response to SRBC. Experiments were carried out on chicks whose burso-cloacal stalk had been ligated at hatching, in order to avoid any contact between the bursal tissues and intestinal material. Chicks subjected to a sham operation, or not operated at all, were used as controls. Results obtained by immunoperoxidase test, using an anti-chicken Ig antiserum, indicate that burso-cloacal stalk ligature leads to an increase in B cells in the bursa of Fabricius 20 days after the operation and a slight decrease after 60 days. The response to SRBC reveals an increase after 20 days, though no variations are found with respect to controls after 60 days. Thus, B lymphocytes mature independently of intestinal stimuli. Furthermore, observations carried out at the age of 20 days indicate that B lymphocytes disappear almost completely from the area of cloacal lymphoid infiltration in chicks with a ligated bursa. It is hypothesised that together with a systemic peripheralisation of B lymphocytes in secondary lymphoid organs and in blood, there exists an intramural local peripheralisation, which is interrupted by ligature of the burso-cloacal stalk.

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↗
PubMed1988

Distribution of B-lymphocytes in the areas of bursal and cloacal lymphoid infiltration.

The present study was carried out on the Diffusely Infiltrated Area of the bursa of Fabricius (DIA) and the area of lymphoid infiltration of the dorsal wall of the cloaca, using immunoperoxidase and electron transmission microscopy, in order to verify the behaviour of antibody-producing cells and their distribution in the two organs. An anti-chicken Ig antiserum was used for this purpose, and the results obtained show that there is a progressive increase in the antibody-producing cells in the DIA, and subsequently also in the cloaca, during the first few weeks of life; the percentage values remain constantly higher in the DIA compared with the cloaca. Electron microscopy made it possible to detect numerous lymphocytes and some plasma cells in the epithelium. Many of the intra-epithelial lymphocytes were immunoperoxidase-positive. The possible role played by the B-lymphocytes found in both organs is discussed.

Animals↗
PubMed1988

Diffusely infiltrated lymphoid areas of the bursa of Fabricius (DIA) and of the cloaca: an embryological study with morphological analogies.

The aim of the present experiment was to verify whether the origin of the DIA is ectodermal or endodermal. A rabbit serum against the epithelial cells of the final portion of the cloaca was prepared. The indirect immunofluorescence method was applied to strips obtained with a cryostat, carefully cut in such a way as to include a part of the cloaca, the burso-cloacal stalk, the DIA, and the bursal plicae. In this way, it was possible to demonstrate that the epithelium of the cloaca, of the burso-cloacal stalk, and of the DIA exhibited an intense fluorescence that could not be observed at the level of the epithelium of the bursal plicae. These findings would appear to indicate that the DIA, like the cloaca and the burso-cloacal stalk, is ectodermal in origin. Furthermore, histological study revealed that the DIA exhibits close structural analogies with the dorsal wall of the cloaca. In both areas, unorganized lymphoid infiltrations of the tunica propria can be seen, and the epithelium does not show any follicle-associated epithelial cells. The glands often assume the aspect of dilated crypts containing intestinal transit material. The epithelium of these glands reveals lymphoid infiltrations at various points, and it is not uncommon to detect accumulations of cells in their lumina. Several groups of eosinophilic granulocytes can also be observed in the tunica propria of these two areas, with a clear predominance at the level of the DIA. These similarities between the cloaca and the DIA might lead one to suppose the existence of a functional as well as a morphological correspondence.

Age Factors↗
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

A contribution to the study of the regulatory system of local immune response in "Gallus domesticus".

The "priming effect" is studied to ascertain whether a regulatory system of local immune response exists and, if it does, what its function is. Bursectomized, bursa-ligated and silica-treated chicks were used, together with control birds (silica selectively damages the follicle associated epithelial -FAE- cells). Agglutinins and direct plaque forming cells (PFC)/spleen were checked. The results confirm that contact between the antigen and the bursal tissue acts as a primary stimulus for immune response and that extrabursal lymphoid sites are unable to act in the same way as the bursa of Fabricius. It seems quite probable, then, that a regulatory system of local immune response exists.

Animals↗
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

The behavior of bursal lymphoid follicle-associated cells after treatment with testosterone.

Administration of androgens produces damage in lymphoid tissue and in the bursa of Fabricius. After IM administration of 5 mg of testosterone propionate (TP) beginning at hatching and continued during the following 4 days, a significant reduction in the bursal weights is observed. Histologically, an increase in the connective tissue is observed and cystic formations are also found. In all cysts examined, there is continuity of the cystic lumen with the free surface. The follicle-associated epithelial (FAE) cells are on the bottom of the pseudocysts and form a separation between the pseudocystic cavity and the lymphoid tissue which is still further inwards. These cells do not lose their esterase activity, even though they are often flattened. Furthermore, they disappear in the pseudocysts deprived of lymphoid tissue. A new hypothesis is advanced that the FAE cells originate from the mesenchyme with differentiation in the histiocytic line.

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↗
PubMed1982

[Immune response in the chicken after intrabursal administration of silica: preliminary observations].

Immune response was studied in various experimental conditions using silica, a macrophage-toxic substance, in order to assess the role attributable to FAE cells, which have been demonstrated to be sensitive to this substance. Antibody response was tested in four different groups comprising seven animals each; the priming effect was studied in particular. It was observed that the silica considerably reduced the priming effect when the dose of antigen was administered in the bursal lumen at times immediately subsequent to the administration of the silica. The priming effect, on the contrary, was still present and was more marked when six hours elapsed between the administration of the silica and the priming dose.

Animals↗
PubMed1982

A contribution to the study of the lymphoid-follicle associated epithelial cells.

The esterase activity in the bursa of Fabricius in 10-day-old chicks is examined by means of serial sections obtained by cutting along the major axis of the lymphoid follicles. The positivity for this enzymatic reaction is not only confirmed to the FAE (follicle associated epithelial) cells of the epithelial frame-work and to isolated cells belonging to the medullary part of the follicle, but it extends in a club-shaped morphological continuity from the FAE cells towards the centre of the follicle. A similar image with a high affinity for acid stainings was also found by means of the H und E technique in suitably orientated sections. Morphological continuity between the FAE cells and the centre-medullary part leads us to suppose the FAE cells and the cells of the centre-medullary part may have a common origin. In the present work, we consider the possibility of FAE cells being of mesenchymatic origin because, besides the fact that they are in continuity with the centre-medullary cells, they appear after CFU (Colony Forming Units) migration, they have no basal lamina, they have certain features which are present in mesenchymatic cells belonging to the histiocytic line, like high esterase activity and micropinocytotic capability and, finally, they are sensitive to carrageenan and silica, which is a peculiarity of macrophages.

Animals↗
PubMed1981

Toxic effect of carrageenan on lymphoid-follicle associated epithelial cells of the bursa of Fabricius of chickens.

The lymphoid-follicle associated epithelial (FAE) cells of the bursa Fabricii of chickens show enzymatic and micropinocytotic activities; they can perform functions reminiscent of those of macrophages. To test this relationship, we checked whether FAE cells are sensitive to carrageenan, a substance widely known to be toxic for macrophages. This substance was gently introduced into the bursal lumen and was left there for a period of 72 to 120 h. The bursae of Fabricius were then examined histologically and histochemically. The result was that the FAE areas had been reduced in number and that their structural pattern had been modified. This effect suggests that FAE cells may be sensitive to carrageenan. The immunological response to SRBC was studied in one group of animals that had received carrageenan. The antibody seemed to elicit an increase in the agglutinins and in the number of direct PFC/spleen against SRBC in comparison with control chickens. On the basis of the morphological and immunological results obtained, the origin and the role of the FAE cells of the bursa of Fabricius are discussed.

Animals↗
PubMed1980

[Horseradish peroxidase (HRP) in intravenous administration is not present in the bursal lumen after interruption of the connection between the bursa and cloaca].

A surgical technique, which we recently described, was used to interrupt the anatomical connection between the bursa of Fabricius and the cloaca. This was done in order to ascertain whether H.R.P. e.v. injected into the wing vein might reach the bursal lumen through the follicle associated epithelial cells, as suggested by Bockman and Stevens, or to establish whether, on the contrary, the way used by H.R.P. to gain access to the bursal lumen might be another:e.v. injected H.R.P. may be excreted by the chicken kidneys, as we demonstrated, then it may pass into the bursal lumen through the cloaca thanks to the duct connecting the two organs. In the present paper we show that the interruption of this connection prevents e.v. injected H.R.P. from gaining access to the bursal lumen.

Animals↗