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Biomedical subjects

T Sminia

Publications and source records attributed to T Sminia.

107 records · Page 6Linked to original sources
PubMed1979

Fixed phagocytes in the freshwater snail Lymnaea stagnalis.

Morphological and histochemical examination of the blood and connective tissue of the freshwater snail Lymnaea stagnalis injected with various types of foreign particulate materials has shown the existence of free as well as fixed phagocytic cells. The morphology of the fixed phagocytes is described, and the phagocytic system of the snail is compared with that of other molluscan species.

Animals↗
PubMed1978

Ultrastructure, histology, and innervation of the mantle edge of the freshwater pulmonate snails Lymnaea stagnalis and Biomphalaria pfeifferi.

The mantle edge of the freshwater pulmonate snails Lymnaea stagnalis and Biomphalaria pfeifferi was investigated with histochemical and ultrastructural methods. The mantle edge gland, which is involved in shell formation, consists of the periostracal groove and the belt. This belt appears to be composed of various regions. In the area of the periostracal groove a number of subepithelial gland cell types occur; these release their products into the groove. Between the groove cells ciliated free nerve endings terminate; the corresponding perikarya occur in the subepidermal connective tissue. Also in the posterior belt region free nerve endings were observed between the epithelial cells; in addition, a particular type of subepithelial gland cell was found in this area. The epithelial cells of this part of the belt have the ultrastructural characteristics of ion and water transporting cells; they are probably involved in calcium deposition and resorption. The possible role of the free nerve endings and of the subepithelial gland cells is discussed.

Animals↗
PubMed1978

Ultrastructural changes in the body wall of Schistosoma mansoni during the transformation of the miracidium into the mother sporocyst in the snail host Biomphalaria pfeifferi.

The ultrastructure of the body wall of the free miracidium of Schistosoma mansoni and the changes occurring within 48 h after penetration into the intermediate host Biomphalaria pfeifferi are described. Within 2 h after penetration the ciliated plates are shed into the haemolymph of the snail and phagocytized by amoebocytes. At the same time the narrow ridges between the plates of the free miracidium expand to form the continuous outer layer of the sporocyst. Within 48 h the entire tegumental structure, consisting of a thin outer layer, connected with sunken nucleated areas, develops to its full extent. The observations are compared with those on Fasciola hepatica.

Animals↗
PubMed1976

Sieve structure of slit diaphragms of podocytes and pore cells of gastropod molluscs.

The ultrastructure of the slit diaphragms between the pedicels of the podocytes of the prosobranch Viviparus viviparus and between the cytoplasmic tongues of the haemocyanin producing pore cells of the pulmonate Lymnaea stagnalis was investigated. In both cell types 2 diaphragms are present in the slits. They form a 3-dimensional sieve structure with holes of respectively 90 x 110 A (podocyte) and 200 x 220 A (pore cell). Injection experiments showed that the size of the holes of the pore cell sieve matches that of particles which can be ingested by theis cell type. The substructure of the sieves of the molluscs is compared to that of the 2-dimensional sieve of the podocytes of the mouse and the rat.

Animals↗
PubMedDate not supplied

Separation of Lymnaea stagnalis hemocytes by density gradient centrifugation.

A chelating anti-clumping (alpha-C) buffer allowed blood cells (hemocytes) of a gastropod, Lymnaea stagnalis to be separated by discontinuous Percoll density gradient centrifugation. The hemocytes of L. stagnalis were separated into five fractions, having a density lower than 10, 20, 30, 40, and 50% Percoll, respectively. Trypan blue exclusion assays showed viability of separated hemocytes to be between 81 and 89%. Cytospin preparations of these hemocytes were examined. Small cells were mainly observed at high densities; at lower densities medium and large hemocytes were also present. No absolute separation was achieved. Some density fractions were enriched for hemocytes with regard to the distributions of two endogenous lysosomal enzymes (alpha-naphthyl acetate esterase and acid phosphatase).

Acid Phosphatase↗
PubMedDate not supplied

Anti-TNP-forming cells in rats after different routes of priming with TNP-LPS followed by intranasal boosting with the same antigen.

To study the reactivity of nasal-associated lymphoid tissue (NALT) and its position in the mucosal immune system, rats were intranasally challenged with 200 micrograms TNP-LPS. Priming had occurred 15 days previous to the challenge with the same antigen and dose, either intranasally, intratracheally, subcutaneously in the cheek or intraperitoneally. The number of anti-TNP antibody-forming cells (AFC) was determined in various tissues using the conjugate TNP/alkaline phosphatase. Generally, anti-TNP AFC were predominantly found in the posterior cervical lymph nodes, while NALT contained hardly any such AFC. The highest response in the posterior cervical lymph nodes occurred on day 5, after subcutaneous priming and intranasal boosting. This also evoked peak responses in several other tissues. The highest response in spleen and lung occurred on day 7 after intraperitoneal priming and intranasal boosting. Irrespective of the immunization route, IgA was the least produced isotype in the spleen as compared to antigen-specific IgG and IgM. In the posterior cervical lymph nodes, besides specific IgG and IgM, a considerable proportion of specific IgA was produced. All four immunization routes yielded anti-TNP antibodies in serum. As for the non-lymphoid cells, the intratracheal-intranasal immunization protocol induced an increase in pulmonary macrophages on days 3 and 5. The immunological role of lung macrophages is discussed.

Administration, Intranasal↗
PubMedDate not supplied

Ontogeny of reticulum cells in the rat intestine and their possible role in the development of the lymphoid microenvironment.

Ontogeny of reticulum cells (RC) in the rat intestine in relation to the development of the gut-associated lymphoid tissue (GALT) was studied using a panel of monoclonal antibodies (mab) directed against RC in peripheral lymphoid organs, ED10-ED15. The mab ED10 specific for RC in the spleen T cell area, recognized an epitope on gut RC, which cells seem to be involved in the influx and accumulation of lymphocytes in the lamina propria and in Peyer's patches (PP) and proximal colonic lymphoid tissue (PCLT). The mab ED11 which recognizes RC in the T cell area and B cell follicles of spleen, stained follicular dendritic cells (FEC) in the B cell area of the mesenteric lymph node (MLN), PP and PCLT. The ED11 expression occurs earlier and reveals stronger staining in MLN as compared to those in PP and PCLT, suggesting the prominent role of MLN in the generation and proliferation of B cells in the gut mucosal immune system. The mab ED13 specific for RC in the B cell area of the lymph nodes, stained the basement membrane of the epithelium overlying PP and PCLT, and high endothelial venules (HEV), suggesting that this might be involved in providing the microenvironment for the development and differentiation of follicle-associated epithelium, and facilitating lymphocyte traffic. The mab ED12 specific for RC in the paracortex of peripheral lymph nodes, gave a diffuse nonspecific staining in the gut, whereas mab ED14 and ED15 are markers for common connective tissue cells. We conclude that the gut RC are morphologically and phenotypically heterogenous. ED10+, ED11+, and ED13+ RC are probably involved in the development of the gut lymphoid microenvironment.

Aging↗
PubMedDate not supplied

The development and structure of mouse nasal-associated lymphoid tissue: an immuno- and enzyme-histochemical study.

This study deals with the structure and development of Nasal-Associated Lymphoid Tissue (NALT) in the mouse. NALT is present in the nasal cavity on both sides at the entrance of the pharyngeal duct. The lymphocytes are organized in B- and T-cell areas covered by an epithelium in which M-cells are present. Immuno- and enzyme-histochemistry showed that NALT is already present at birth. Before birth, accumulations of Ia-positive dendritic cells and a few B lymphocytes were the first signs of the formation of NALT. These cell accumulations occurred just under the epithelium in the nasal floor. At birth, NALT could be distinguished as an accumulation of mainly B lymphocytes and Ia positive dendritic cells in a network of reticulum cells. The covering simple epithelium showed crypt-like invaginations. B- and T-cell areas appeared at seven days after birth. High endothelial venules (HEV) were observed from day 7 onward; from day 14 they could be stained with the HEV-specific monoclonal antibody MECA-325. Ia-positive dendritic cells increased in number during ontogeny. They occurred both in NALT and between the covering epithelial cells. Also, some epithelial cells expressed the Ia-antigen. The number of acid phosphatase positive macrophages increased steadily during ontogeny. The cells were mainly observed in the connective tissue surrounding NALT and just under the epithelium. They displayed antigenic determinants characteristic of macrophages (Moma-1, Moma-2). The structure and development of NALT are compared with those of other parts of the mucosa-associated lymphoid tissue.

Animals↗