ABSTRACT
Background: The thymus is one of the primary lymphoid organs other than being the bone marrow. It is responsible for the provision of thymus-processed lymphocytes (T lymphocytes) to the whole body. Aim of the study: To study the microscopic architecture of the cortex and medulla, structure and type of epithelial cells, nature of connective tissue stroma, vasculature of thymus organ, the morphology of Hassall Corpuscle (HC). To study the histometric analysis like estimation of volume and diameter of HC at various gestational age. Method: Total 20 aborted and still born fetuses ranging from 17-39 weeks of gestation were used for the study. After embalming, meticulous dissection, thymus gland was weighed and fixed with formalin. The various histological and histometric parameters were observed. Results: The cortex and medulla were well demarcated by the 17th week. The weight and volume of the thymus were proportionately increased as the fetal age advanced. Early phase had thick mucoid interlobular septae whereas the later phase had thin, reticular interlobular septae. Four different types of HC (SHC, CHC I, CHC II and DHC) in fetus were seen. The presence of solid HC at the periphery of the medulla and degenerating HC at the central core of the medulla tends to postulate the direction of maturation which is from the periphery to the center of the medulla. Conclusion: The findings of the present study is in conformity with studies related to the volume and size of the thymus with respect to gestational ages and histological features related to parenchymal and mesenchymal tissue composition and its various components. However, the present study noted different types of Hassall’s Corpuscles which are reported in the adult thymus and the findings lead to further discussion on the maturation and differentiation of Hassall’s Corpuscles in human fetal thymus.
ABSTRACT
El timo fetal es una estructura que desde que fue visualizada por primera vez por ultrasonido en el año 1989 ha ido ganando en interés sobre todo en la última década debido a su fácil visualización con los equipos de mayor resolución. Con este artículo se pretende poner al alcance de los especialistas dedicados al diagnóstico prenatal una revisión de los aspectos más recientes de la evaluación del timo fetal con su medición en la vista ecocardiográfica de los tres vasos. La evaluación de su tamaño por los diferentes métodos ya sea midiendo su diámetro transverso, su perímetro y más recientemente la relación tímico / torácica ha permitido demostrar cómo su ausencia o hipoplasia se relaciona con diferentes alteraciones fetales tales como: cardiopatías complejas sobre todo conotruncales y del arco aórtico, retardos del crecimiento intrauterino, preeclampsia materna, signo precoz de corioamnionitis y prematuridad, así como asociadas con delección 22q 11 y en diferentes trisomías como la 21, 18 y 13 y en la predicción del estatus inmunológico después del nacimiento. La evaluación ecocardiográfica del timo fetal por la medición de los tres vasos que resulta posible en más del 90 % de los casos aporta otro elemento de valor al examen prenatal del feto.
The fetal thymus is a structure since it was displayed for the first time by ultrasound in 1989 has been gaining interest especially in the last decade due to its easy viewing with higher resolution equipment. This article aims to make available a review of the most recent assessment of fetal thymus with its measurement in echocardiographic view of the three vessels for those prenatal diagnosis specialists. Assessment of size by different methods either by measuring its transverse diameter, its perimeter and more recently the relationship thymic / thoracic, has demonstrated that its absence or hypoplasia is related to different fetal defects such as complex heart diseases , especially conotruncal and aortic arch, intrauterine growth delay, maternal preeclampsia, early sign of chorioamnionitis and prematurity, as well as those associated with 22q 11 deletion and in different trisomies such as 21, 18 and 13 and in predicting immune status after birth. Echocardiographic assessment of fetal thymus by measuring the three vessels, which is possible in 90% of cases, adds another valuable element to prenatal fetus examination.
ABSTRACT
To evaluate histopathologic differences in the thymus of Wistar Albino rat fetuses prenatally exposed to valproic acid (VPA), folic acid (FA) and vitamin E (Vit-E). VPA (400 mg/kg), FA (400 mcg/kg) and Vit -E (250 mg/kg) were administered to rats on each of gestation days 8, 9 and 10. The fetuses (n:24) were divided into four groups: control, VPA, VPA+Vit-E and VPA+FA groups. On the 20th day of gestation, all pregnant rats were sacrificed and the fetuses were extracted. Thin sections from thymus of live fetuses were stained with uranyl acetate-lead citrate and were examined under transmission electron microscope. The histopathological findings of control group was normal. In VPA group, it showed extensive degenerative changes by VPA were on all tissue compartments when compared to controls. In VPA-FA group, vacuoles, mitochondrial cristalysis and swelling were decreased in cytoplasm. In VPA-Vit-E group, lipid storage and vacuolization were observed. Mitochondrial cristalysis decreased. Our aim in the present study is to analyze histopathological changes which may occur in a high risk experimental model after giving of VPA. In addition, protective roles of the administration of FA and Vit-E are assessed.
Se realizó este estudio para evaluar las diferencias histopatológicas en el timo de fetos de ratas Wistar Albinas expuestas prenatalmente a ácido valproico (VPA), ácido fólico (AF) y vitamina E (Vit-E). VPA (400 mg/kg), FA (400 mcg/kg) y vitamina E (250mg/kg) administradas a ratas en los días 8, 9 y 10 de gestación. Los fetos (n=24) fueron divididos en cuatro grupos: control, APV, APV + vitamina E y VPA + FA. En el día 20 de gestación, todas las ratas preñadas fueron sacrificadas y los fetos fueron extraídos. Se obtuvieron secciones delgadas del timo de los fetos y se tiñeron con citrato de uranilo - acetato de plomo, siendo examinados al microscopio electrónico de transmisión. Los hallazgos histopatológicos del grupo control fueron normales. En el grupo VPA, se observaron cambios degenerativos en todos los compartimentos de tejido en comparación con los controles. En el grupo VPA+FA, las vacuolas, cristalisis mitocondrial e inflamación se redujeron en el citoplasma. En grupo VPA + Vitamina E, se observó el almacenamiento de lípidos y vacuolización. La cristalisis mitocondrial disminuyó. El estudio permitió analizar los cambios histopatológicos que pueden ocurrir en un modelo experimental de alto riesgo después de la administración de VPA, además, las funciones de protección por la administración de AF y vitamina E.
Subject(s)
Animals , Female , Pregnancy , Rats , Folic Acid/pharmacology , Valproic Acid/pharmacology , Thymus Gland , Thymus Gland/pathology , Vitamin E/pharmacology , Fetal Development , Microscopy, Electron, Transmission , Models, Animal , Rats, Wistar , Thymus Gland/embryology , Thymus Gland/ultrastructureABSTRACT
Introduction: Recent advances in ultrasound technology have made possible an easy and accurate visualization of the fetal thymus in vast majority of cases. On ultrasound, thymus is visualized in the upper mediastinum, between sternum and great vessels. Despite several previous papers published, there is no consensus regarding a clear correlation between these measurements and thymus hypoplasia. Nowadays thymus evaluation is not mandatory in routine ultrasound examinations, however at referral centers its evaluation could help to identify patients with high risk for microdeletion 22 q11. Recently it has been proposed a new method to assess the thymus; the thymus-torax ratio, this has been proven to be altered in 95 percent of fetuses with congenital heart disease and microdeletion 22q11. This study describes the experience at our unit using this new tool as part of routine fetal examinations. Materials and methods: A descriptive study, 44 ultrasound examinations between 19 and 38 weeks of gestation, in which thymus-thoracic ratio was measured as part of the routine fetal examination at this perinatal referral center. Objective: Determinate the factibility of measurement of the thymus- thoracic ratio in routine fetal ultrasound examinations. Results: The thymus- thoracic ratio was measured successfully at our routine fetal ultrasound examinations, results were similar to those previously reported. The ratio was not affected by fetal or maternal pathology and gestational age. Discussion: The thymus thorax ratio appears to be constant through gestation despite of maternal and fetal pathologies; it seems to have advantages over other types of measurements described in previous publications. However, due to small number of cases we suggest a new analysis with a larger number of patients.
Avances recientes en ultrasonido han permitido una visualización fácil y certera del timo fetal en la gran mayoría de los fetos examinados. En el examen de ultrasonido, el timo se encuentra en el mediastino superior, entre el esternón y los grandes vasos. A pesar de numerosas publicaciones, actualmente no existe consenso respecto de las técnicas utilizadas para realizar estas mediciones y el diagnostico de hipoplasia de timo. La evaluación del timo fetal no forma parte del examen de ultrasonido de rutina. Sin embargo, en centros de referencia pudiera ser de utilidad para identificar los pacientes con alto riesgo de presentar microdelecion 22q11. Recientemente se ha propuesto una nueva forma de evaluar el timo a través de la relación timo- tórax, la cual ha probado estar alterada en el 95 por ciento de los fetos con cardiopatía congénita y microdelecion 22q11. Este estudio describe nuestra experiencia en la incorporación de esta nueva herramienta en el examen de rutina fetal. Materiales y métodos: Estudio descriptivo, 44 reportes de exámenes ultrasonográficos realizados entre las 19 y 38 semanas de gestación, en los cuales se realizó la medición de la relación timo- tórax como parte del examen fetal de rutina, en este centro de referencia perinatal. Objetivo: Describir la experiencia de la unidad en la medición de la relación timo- tórax en el examen ultrasonografico fetal de rutina. Resultados: La medición de la relación timo- tórax fue incorporada de manera exitosa como parte del protocolo estándar de mediciones realizado en la unidad, con resultados similares a los reportados previamente. La relación no fue afectada por patología fetal o materna ni edad gestacional. Discusión: la relación timo- tórax parece ser constante a través de la gestación a pesar de la presencia de patología materna o fetal, siendo una medida que aparentemente provee ventajas sobre las otras descritas previamente en la literatura. Sin embargo debido al tamaño de la muestra...
Subject(s)
Female , Pregnancy , Chromosome Deletion , Thymus Gland/abnormalities , Thymus Gland , Ultrasonography, Prenatal , Gestational Age , Reference Values , Thymus Gland/pathology , Thorax , Chromosome DisordersABSTRACT
Objective:To investigate the effect of IL-7 on differentiation of thymic T lymphocytes and dendritic cells' differentiation in vitro.Methods:Thymic lobes were apspectically removed from 15-day-old or 16-day-old mouse fetueses and were cultured by the way of fetal thymus organ cultures (FTOC) in vitro.Lobes were cultured in the dishes with or without Interleukin-7(IL-7),then collected the cultured cells respectively.The expression of CD4,CD8,CD11c,B220,Ia,and CD11b was detected by flow cytometry,and the morphology was observed under the ligt microscope.The proliferation of these cells was determined by cell counting.The cultured cells were used as stimulators for allogeneic T cells,whose proliferation were detected later by MTT method.Results:The result of cell counting indicated that the total amount of the thymocytes was decresed obviously after being cultured with IL-7,while the proportion of CD4~+ CD8~+ thymocytes decreased,the proportion of CD4~- CD8~-,and CD4~- CD8~+ thymocytes increased,and no much difference in the amount of CD4~+ CD8~- thymocytes was found.In addition,the amount of B lymphocytes,natural killer cells,and dendritic cells increased in different degree.Conclusion:IL-7 participates in differentiation and development of thymic T lymphocytes and dendritic cells.
ABSTRACT
PURPOSE: Many researchers have tried to develop animal models that mimic the human immune system, e.g. a humanized mouse model, to improve the engraftment of hematopoietic stem cells and develop human immune cells in an animal model. This study evaluated the feasibility of the cultured human umbilical cord blood (hUCB)-derived CD34(+) cells for cell expansion, in Rag2(-/-)gamma(c)(-/-) mice, and establish co-transplantation with human fetal thymus/liver tissue (Thy/Liv) under the kidney capsule. METHODS: Co-transplantation of hUCB-derived CD34(+) cells with Thy/Liv was performed. The hUCB-derived CD34(+) cells were prepared by freshly thawing (G1) and culturing for 7 days with two types of cytokine combinations (G2, G3). The CD45(+) cell populations were measured at 6, 8, 10 and 16 weeks in the peripheral blood. The splenocytes were cultured with mitogenic stimuli (PHA -L or IL-2) at 20 weeks post- transplantation, and the proliferation of human immune cells was evaluated. RESULTS: There were no significant differences in the human CD45(+) cell populations at 6, 8, 10 and 16 weeks post-transplantation between the groups. In the cultured splenocytes at 20 weeks post-transplant with PHA-L or IL-2, there was remarkable expansion of CD3(+) cells in the three groups. Although no CD19(+) cells were detected in the spleen, human Ig G was detected in the sera of these mice. CONCLUSION: The cultured and expanded hUCB-derived cells with cytokine combinations might be a feasible cell source in humanized mouse modeling. In addition, human immune cells can be reconstituted from the co-transplantation of Thy/Liv and cultured hUCB-derived CD34(+) cells.