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A Zapata

Publications and source records attributed to A Zapata.

At least 73 records · Page 4Linked to original sources
PubMed1991

Rat thymic cultures: morphological and phenotypical characterization.

Rat thymic cultures have been established in order to analyse the morpho-functional characteristics of thymic epithelial and non-epithelial cells in vitro. Stromal cultures, originating from implanted thymic fragments, consist of fibroblasts occupying most of the culture surface, epithelial cells forming discrete colonies, thymocytes and bone marrow-derived cells. Epithelial cells show a low class II MHC antigen expression, which is highly increased in semi-adherent cells, and do not interact with thymocytes. Thymocytes proliferate extensively at the beginning of the culture, but almost disappear at the end of the first week; however, restarting of thymocyte proliferation occurs during the second week of culture. Bone marrow-derived cells include ED- Ia+ CR3- IL-2R- dendritic cells (DC), ED+ Ia+ CR3+ IL-2R+ non-adherent thymic phagocytic cells (PTR) and ED+ Ia- CR3- IL-2R- adherent type 1 and 2 macrophages, derived from PTR. Both PTR and DC establish lympho-stromatic complexes with thymocytes present in the cultures. These results suggest that PTR and DC present in rat thymic cultures belong to different cell lineages, and that they are, respectively, the in vitro equivalents of intrathymic macrophages and interdigitating cells.

Animals↗
PubMed1990

Enzyme- and immuno-histochemical study of the thymic stroma in the rainbow trout, Salmo gairdneri, Richardson.

Owing to the lack of data about thymic non-lymphoid cells in fish we decided to perform a histochemical characterization of these cells in order to ascertain their relationships to other thymic components. In the present study we analyze the enzyme-histochemical patterns for acid phosphatase, alkaline phosphatase, non-specific sigma-naphthyl acetate esterase and 5' nucleotidase activities, as well as the presence of keratin demonstrated by immunoperoxidase staining, in the non-lymphoid cell populations of the thymus of the rainbow trout, Salmo gairdneri. According to their location in the organ, morphology and histochemical reactivities, we were able to define seven different subpopulations of keratin-positive epithelial cells: 1) Epithelial cells limiting with the capsular and septal connective tissues; 2) Subcapsular epithelial cells; 3) Stellate epithelial cells of the inner thymic zone; 4) Large, ovoid epithelial cells of the inner thymic zone; 5) Acidophilic epithelial cells of the outer thymic zone; 6) Cystic cells; and 7) Goblet cells. The significance of the heterogeneity of the epithelial cell (EC) population, its specific distribution in the organ, which apparently conforms distinct cell microenvironments, as well as the possible phylogenetical relationships between these microenvironments and the classical cortex and medulla of the mammalian thymus, are discussed.

5'-Nucleotidase↗
PubMed1989

Different sensitivity to the dexamethasone treatment of the lymphoid organs of Rana perezi in two different seasons.

Adult female frogs (Rana perezi) have been used to analyze structural and morphometrical changes which affect lymphoid organs after treatment with a single dose of dexamethasone (DX). Special attention was given to the distinct sensitivity observed during two different periods of the year. Morphological differences were found between adult control frogs sacrificed in November and February. In February, frogs showed degenerated thymic reticular epithelial cells but lesser numbers of cortical pycnotic and mitotic thymocytes than in November. Splenic lymphoid tissue was clearly less well developed in February. No significant variations were found in the morphometrical parameters of jugular bodies whereas the number of lymphocytes of both peripheral blood and bone marrow was significantly higher in February than in November. In contrast, frogs sacrificed in February exhibited less drastic variations as well as a more delayed response to DX-treatment than those of November. The reported differential changes could be attributed to possible distinct levels of circulating sexual and nonsexual steroids during both seasonal periods.

Animals↗
PubMed1989

Pulmonary phospholipids in amniotic fluid of pathologic pregnancies: relationship with clinical status of the newborn.

We evaluated phospholipids, C-peptide and cortisol levels in amniotic fluid of 203 pathologic pregnancies (63, class A, B and C diabetics; 11 class D, F and H diabetics; 44 preclampsia and 85 Rh-isoimmunization); the control group was 82 normal pregnant women. There was an acceleration of fetal pulmonary maturation in women with preclampsia and severe Rh-isoimmunization in class D, F and H diabetics (at 34 weeks gestation the incidence of mature surfactant (lecithin/sphingomyelin greater than or equal to 2.7 and presence of phosphatidyl-glycerol) in these groups was 30%, 50% and 100%, respectively, while it was zero in the control group). At 37 and 38 weeks only 44.4% of the class A, B and C diabetics had mature surfactant and there was a significant difference with respect to the control group (x2 = 4.9; p less than 0.05); C-peptide levels in these diabetics (class A, B and C) were higher than in controls (p less than 0.001); in pregnant women with accelerated fetal lung maturation they were lower. We demonstrated a close relationship between fetal pulmonary maturity and the type of surfactant in amniotic fluid, which was independent of gestational age.

Amniotic Fluid↗
PubMed1988

Effects of neonatal treatment with estrogens on the development of the thymus in rats.

In order to study the effects of sex hormones administered during the neonatal period on the thymic development we have injected 5 days old female rats with a single dose (0.1mg) of estradiol benzoate. The evolution of the thymus gland after treatment was morphometrically analyzed. The thymus of the estrogen-injected animals diminished in size between the 7th and the 15th day, increasing afterwards. The cortex was the most sensitive compartment in the thymus to estrogenic treatment. Both thymic involution and enlargement were associated to changes in the frequency of large lymphoid cells in the subcapsular region and variations in the thymic cortex weights. The observed effects are tentatively attributed to alterations in the thymocyte differentiation probably due to modifications in the secretion of thymic hormones.

Animals↗
PubMed1988

Alterations in the peripheral lymphoid organs and differential leukocyte counts in Saprolegnia-infected brown trout, Salmo trutta fario.

The number of circulating leukocytes and the structure of splenic and renal lymphoid tissue were comparatively analysed in healthy and Saprolegnia-infected wild brown trout, Salmo trutta fario. Sick trout showed lymphopenia, mainly due to decreased numbers of circulating small lymphocytes, and heterophilia. The splenic and renal lymphoid tissue of infected trout exhibited similar changes, consisting of cellular depletion, lymphoid cell degeneration, and vascular alterations with blood vessel enlargement and hypertrophy of sinusoidal endothelial cells. Furthermore, the endothelial cells in the spleen and kidney of the infected trout contained cytoplasmic vesicles filled with material of possible fungal origin. The absence of a reticular sheath was also evident in the splenic ellipsoids. These results suggest some immunodepression in Saprolegnia-infected trout which might favour the course of the disease.

Animals↗
PubMed1988

Amniotic fluid phospholipids and foetal lung maturation.

An analysis was made of samples of amniotic fluid from 82 pregnant women with normal pregnancies, ranging from 29 to 40 weeks of amenorrhoea. Lipid extraction was quantitative and individual phospholipids were isolated by two-dimensional chromatography. The lecithin/sphingomyelin ratio (L/S) increased significantly (t = 2.17; p less than 0.05) between 35 and 36 weeks of amenorrhoea (from 2.9 +/- 1.0 to 4.3 +/- 1.7). Phosphatidyl-glycerol (PG) was detected from 35 weeks of pregnancy, the time at which the incidence of amniotic samples with mature surfactant (L/S greater than or equal to 2.7 and presence of PG) was 9%; mature surfactant incidence increased to 55.5% at 36 weeks and 100% at 37 or more weeks. There was a good correlation between surfactant levels in amniotic fluid and new-born respiratory function.

Amniotic Fluid↗
PubMed1988

Detection of Thy-1+ cells in the developing thymus of the lizard, Chalcides ocellatus.

The ontogenic appearance of Thy-1+ cells was studied in the thymus of the lizard, Chalcides ocellatus, by indirect immunofluorescence using a rabbit antibrain antiserum produced against surface determinants shared by both the thymus and the brain lizards. Thymic Thy-1+ cells were first detected at stage 37. They increased rapidly reaching adult numbers by stage 41. Apparently Thy-1+ cells differentiate from lymphoid precursors arriving at the thymus analage before stage 37. The results are compared to those found during the differentiation of Thy-1+ thymocyte in murine thymus and agree with former reports on the thymic development in Chalcides using rabbit antisera against adult thymocyte marker(s).

Animals↗
PubMed1987

Ultrastructure and changes during metamorphosis of the lympho-hemopoietic tissue of the larval anadromous sea lamprey Petromyzon marinus.

The ultrastructure of the lympho-hemopoietic tissue of the typhlosole and opisthonephros of larval Petromyzon marinus was studied throughout the life cycle. In both locations, lympho-hemopoietic tissue houses a connective tissue stroma and is irrigated by a system of enlarged blood sinuses lined by a continuous endothelium. The typhlosolar and opisthonephric lympho-hemopoietic tissue consists of mature and developing blood cells belonging to erythroid, lymphoid, monocytic and granulocytic lineages. During metamorphosis there is a total degeneration of the larval opisthonephros and a full transformation of the digestive apparatus. As a consequence of these modifications the typhlosole and the opisthonephros lose their hemopoietic capacity. These changes are discussed in view of the role played in them by the so-called "hemopoietic inductive microenvironments", principally the stroma supporting apparatus and vascularization pattern.

Animals↗
PubMed1987

Effects of dexamethasone on the lymphoid organs of Rana perezi.

Owing to the possible importance of steroids in the mutual neuroendocrine-immune influences found in lower vertebrates, we study the structural and morphometrical changes induced by a single dose of dexamethasone, a synthetic corticosteroid, on the lymphoid organs of the frog Rana perezi. The dexamethasone treatment produces thymic involution with massive destruction of cortical lymphocytes, intense peripheral lymphopenia with lymphocyte redistribution to the bone marrow from peripheral blood and spleen. The effects on the spleen were less dramatic than in the thymus, but, the proportion of white pulp underwent a significant decrease and the size of splenic lymphoid follicles diminished. Our results demonstrate that Rana perezi is a corticosensitive species although the induced corticosteroid effects were less drastic than those described in other vertebrates, mainly mammals.

Animals↗
PubMed1987

Stereological analysis of the ultrastructure of the early chick embryo cell types involved in sorting out.

Analysis of the aggregates obtained from the prenodal region of the chick embryo (stage 5) show the existence of three cell types which sorted out. The application of morphometrical and stereological methods show that each of these cell types has a characteristic subcellular organization which is discussed with respect to the cytometrical characteristics of embryonic cells of stage 5. This early ultrastructure of each cell type is presumably related to its state of differentiation and consequently to some of the potential morphogenetic roles.

Animals↗
PubMed1986

Morphological differentiation of mitochondria in the early chick embryo: a stereological analysis.

The morphological evolution of mitochondria in three cell types of chick embryo in neurulation was analyzed by stereological methods. Mitochondria, showing a random distribution, were characterized by moderate electron-dense matrices and normal cristae. The numerical density of mitochondria significantly increased in the neuroectoderm and epiblastic cells while their volume density remained unchanged. The mitochondria in mesoderm cells were ellipsoidal (axial ratio 2:1) at stages 5 and 8 although they underwent an elongation in neuroectoderm and epiblastic cells (axial ratio from 2:1 to 1.6:1). The individual size of "average mitochondria" in the mesoderm cells was smaller than in other cell types. The total V/S (volume/surface) ratio of mitochondria decreased during neurulation. These morphological changes have been discussed emphasizing the possible metabolical role of mitochondria during morphogenesis.

Animals↗
PubMed1986

Seasonal variations in the immune response of the tortoise Mauremys caspica.

The primary and secondary immune responses to sheep erythrocytes (SRBC) have been characterized in the tortoise Mauremys caspica in terms of circulating antibodies and PFC response in two different seasons: summer and autumn. Primary immunization is followed by the appearance of both 2ME-sensitive antibodies and splenic PFCs in autumn but not in summer. During the secondary response, 2ME-resistant antibodies were found in both seasons, but the number of PFCs was significantly reduced during summer. The results are discussed from the perspective of the role played by glucocorticosteroids in the seasonal variations affecting reptilian immunoreactivity.

Animals↗
PubMed1986

[Anderson's disease. Apropos of a new case].

A new case of Anderson's disease in a 3-month-old black female infant is presented. This diagnosis should be considered in infants with chronic diarrhoea, fatty stools, failure to gain weight which may be present from birth, low serum cholesterol concentration (less than 70 mg/ml), low plasma triglyceride levels, and hypobetalipoproteinaemia. However, suspicion of diagnosis clinically can be certainly verified by intestinal biopsy showing characteristic epithelial cell pattern. Steatorrhoea may be effectively treated by substituting medium for long-chain triglycerides in the diet. This disorder needs to be distinguished from familial hypobetalipoproteinaemia as well as abetalipoproteinaemia, and it prognosis is good, because of absence of acanthocytosis, neurological involvement and ocular lesions.

Abetalipoproteinemia↗
PubMed1985

Ultrastructural changes in the spleen of the natterjack, Bufo calamita, after antigenic stimulation.

In the present study comparative aspects of the ultrastructure of the spleen were analyzed in non-immunized and T-dependent antigen-challenged natterjacks, Bufo calamita. Special attention is focused on the role of the non-lymphoid components in the splenic immunoreactivity. Ten days after primary immunization with sheep erythrocytes, splenic lymphoid follicles increase considerably in number and size. By that time, lymphoblasts, medium and large lymphocytes abound in the periphery of the white pulp near the marginal zone. Meanwhile, in the red pulp numerous monocytes migrating across the sinusoidal walls apparently transform into giant, dendritic-like cells. Twenty days after immunization the splenic lymphoid follicles decrease in number, although certain reactivity persists and numerous plasma cells occur in the cell cords and sinusoids of the red pulp. These results are discussed comparatively with those reported in other lower vertebrates.

Animals↗
PubMed1985

Dendritic immune complex trapping cells in the spleen of the snake, Python reticulatus.

The spleen of the snake Python reticulatus, was investigated as to its general histology as well as the presence of immune complex trapping cells both at the light and electron microscopical level. Histological examination revealed that the spleen of this reptile was encapsulated and contained some trabeculae. In the splenic parenchyma two different regions could be distinguished: viz. red and white pulp. The white pulp appeared to be arranged around "central arterioles" and their smaller branches extending towards the periphery of the white pulp. The red pulp was composed of blood sinusoids and cell cords. Electron microscopy revealed at least three types of non-lymphoid cells in the white pulp of the spleen of python: reticulum cells, forming the framework; some macrophages and dendritic cells predominantly located in the periphery of the white pulp. Of these types of non-lymphoid cells, only dendritic cells were able to trap and to retain intravenously injected horseradish peroxidase (HRP)-rabbit-anti-HRP immune complexes on their cell surface as determined by enzymehistochemistry at the light and electron microscopical level. These dendritic cells were frequently found in association with collagen fibres and did not engulf large quantities of carbon particles. These data suggest that dendritic cells in the spleen of the python might be the phylogenetic precursors of the mammalian follicular dendritic cells.

Animals↗
PubMed1985

Seasonal changes in the thymus and spleen of the turtle, Mauremys caspica. A morphometrical, light microscopical study.

Mauremys caspica has been used to analyze morphological changes which affect lymphoid organs (thymus and spleen) throughout the year related to annual variations of circulating steroid hormones. Both organs undergo seasonal variations which, however, differentially affect their distinct compartments (cortex and medulla in the thymus; PALS and PELS in the splenic white pulp). The greatest thymic involution occurs in summer, with some recovery at the beginning of autumn and a slow decrease throughout the winter. At the beginning of spring, although the gland increases somewhat in size, the thymic cortex is only slightly developed. Only at the end of spring does the thymus reach a large size, with a well developed cortex and medulla. In the same season, the splenic lymphoid tissue reaches its maximum development, but in the summer it undergoes a dramatic decrease. These results are confronted with the activity of steroid hormones measured by radio-immune assay, confirming possible relationships between the development of lymphoid organs during summer and spring, and levels of circulating corticosterone and testosterone. The decrease in lymphoid tissue during winter could be related to temperature-dependent membrane homeoviscosity.

Animals↗