1,720,995 research outputs found
Ultrastructural study on the plical epithelium of the bursa of Fabricius in chick embryos: Influence of partial decerebration and hypophyseal allografts
No full textThe bursa of Fabricius of 18 day normal and partially decerebrated chick embryos, and partially decerebrated embryos bearing a hypophyseal allograft was analysed by scanning and transmission electron microscopy, focusing on the ultrastructural characterisation of the plical epithelium. The plicae of the normal bursa consist of interfollicular (IFE) and follicle associated epithelium (FAE). The FAE is composed of typical polygonal cells and is supported by a layer of epithelial cells which appears as a continuation of the corticomedullary epithelium. Bordering cells lie between the FAE and IFE. The IFE is composed of 4 cell types: (1) undifferentiated, (2) goblet, at various stages of maturity, (3) prismatic, and (4) globular light cells. Partially decerebrated embryos showed a gross impairment of plical epithelium development and the complex of FAE and IFE cells was largely undifferentiated. Partially decerebrated embryos with a hypophyseal allograft displayed the same cellular types as observed in controls, thus indicating a restored differentiation of plical epithelium. These findings suggest that the hypophysis affects the differentiation of plical epithelium during ontogenesis
Vasilij Grossman: il comunismo come antitesi della libertà
No full textIl saggio ricostruisce la critica operata dallo scrittore ebreo-russo Vasilij Grossman allo Stato sovietico e all'ideologia totalitaria marxista-leninista, evidenziando in particolare il carattere antimoderno e antioccidentale che l'autore attribuisce alla rivoluzione bolscevic
Husserl: l'Occidente come teoria e come libertà
No full textInterpretazione dell'idea husserliana di Occidente, concepito come luogo di nascita del pensiero filosofico e spazio della libertà che a tale pensiero fa riferimento. Per la sua ripresa dei motivi originari del pensiero filosofico e per la sua riaffermazione della inestricabilità del rapporto fra individuo e libertà, Husserl viene qui incluso fra i "difensori dell'Occidente", come recita il titolo del volume collettivo ideato da Giampietro Berti e Luciano Pellicani
Ontogeny of thymocytes in sea bass Dicentrarchus labrax: studies with monoclonal antibodies.
No full textThe monoclonal antibody DLT15 directed against thymocytes of the sea bass Dicentrarchus labrax specifically recognised an antigen determinant(s) expressed during development of thymic lymphoid cells. While immunoreaction is excluded from lymphoblast-like cells present in the thymic anlage, it was first detected one month posthaching in thymocytes. Thereafter, a marked increase in number of immunoreactive cells occurred mostly in the outer region of the thymus. This study aimed to analyse the chronology and some features of thymocyte differentiation
Histology of developing thymus in sea bass Dicentrarchus labrax (L.).
No full textThe histology and chronology of thymic development in sea bass were described.
Day 27 post-hatch: the thymus appears as a paired anlage on dorsal caudal portion of both gill chambers, predominantly filled with lymphoid cells associated with the pharyngeal epithelium.
Day 38 ph: the penetration into the parenchyma of connective trabeculae begins to divide it into lobes and carries the vascular supply. This process is accompanied by the development of a subcapsular, inner thymic region.
Day 53 ph: the active lymphopoiesis and enlargement of the outer region, filled by numerous small lymphocytes, define evident regional differences in the thymus, that are retained in older stages.
In one-year old bass, the organ is completely encapsulated by connective, the pharyngeal epithelium detaches from the lymphoid tissue. The thymus, which still retains a superficial position, does not show evident signs of regression
Immunocytochemical detection and cytomorphology of lymphocyte subpopulations in a teleost fish Dicentrarchus labrax
No full textThe monoclonal antibodies DLT15 and DLIg3
directed against thymocytes and serum immunoglobulins
of the sea bass (Dicentrarchus labrax, L.) were used to
study cells from the thymus, head kidney, spleen, gut-associated
lymphoid tissue and peripheral blood leukocytes
of this fish by immunofluorescence and pre-embedding
immunoelectron microscopy. Immunofluorescence
and flow cytometry of leukocyte fractions revealed
a large number of DLT15-positive cells in the
thymus (~80%) and intestine (~55%) and fewer cells in
the spleen (~7%), head kidney (~6%) and peripheral
blood (~3%). DLT15-positive cells had two main morphologies,
both detectable among thymocytes: a large
round heterochromatic nucleus with light sparse cytoplasm
(type a) and an irregular and heterocromatic nucleus
with cytoplasm rich in polysomes and mitochondria
(type b). Type b was most represented in spleen,
head kidney, intestine and blood. We suggest that the
type b morphology represents more differentiated lymphocytes.
Flow cytometry revealed numerous DLIg3-
positive cells in the head kidney (~33%), spleen (~30%)
and peripheral blood leukocytes (~21%) and fewer positive
cells in the intestine (~3%) and thymus (~2%).
DLIg3-positive cells had the morphology of lymphocytes
(with a large round nucleus) or macrophages in all
tissues. Plasma cells lacked membrane immunoreactivity.
This is the first ultrastructural characterisation of putative
T- and B-lymphocyte subpopulations in a fish species;
these subpopulations are differentially distributed
in teleost lymphoid organs
Immunohistochemical, ultrastructural and biochemical evidence of adrenal chromaffin cell subtypes in sea bass Dicentrarchus labrax (L.).
No full textImmunohistochemistry of gut-associated lymphoid tissue of the sea bass Dicentrarchus labrax (L.)
No full textHistology revealed scattered lymphoid cells at all levels of the digestive tract of the sea bass Dicentrarchus labrax (L.), notably in the mucosa and submucosa. Immunohistochemistry with monoclonal antibodies against T cells (DLT15) and immunoglobulin-bearing cells (DLIg3 and DLIg13) demonstrated
the presence of a gut-associated lymphoid tissue. Quantitative analysis showed that the concentration of DLT15-positive cells largely exceeded that of Ig-bearing cells, while the number and the distribution of DLIg3- and DLIg13-immunoreactive cells were superimposable. An apparent gradient in the number of lymphoid cells was present, concentrating them towards the anus. This suggests that, as in other fish species, the posterior gut acquired higher immunological relevance
Immunocytochemical detection of thymocyte antigenic determinants in developing lymphoid organs of sea bass dicentrarchus labrax (L.)
No full textThe monoclonal antibody DLT15 specifically recognised antigenic determinants expressed during development of thymic lymphoid cells of the sea bass Dicentrarchus labrax (L.). They were first detected at day 30 post-hatching in
the thymus of fish maintained at 16) C; thereafter, a marked increase in the number of immunoreactive cells occurred mostly in the outer region of the thymus. The appearance of DLT15-immunoreactive cells in the lymphoid organs was in the sequence thymus, head-kidney and spleen. The thymus thus
appears to be a primary lymphoid organ in the sea bass. Infrequent cells sharing the antigenic determinants expressed on thymocytes were localised in the developing head-kidney and spleen
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