Made available in DSpace on 2014-08-20T14:24:47Z (GMT). No. of bitstreams: 1 Dissertacao Patricia Mussi Escobar.pdf: 4797347 bytes, checksum: 854e1a006990b1ef26960eb06da6b9f9 (MD5) Previous issue date: 2013-03-15 / The research was developed based on the thesis of Vetromille-Castro (2007), in which collaboration and autonomy were considered values that fostered interaction and maintained the cohesion and emergency of the group. However, Vetromille-Castro considered that there were other values besides collaboration and autonomy which were shared among co-valorizing individuals (Piaget, 1973). It is precisely on this hypothesis that we developed this work. In this research we studied the interactive process in a group of trainee teachers of Spanish as a Foreign Language (SFL) in virtual learning environment forums. We analyzed the posts of 30 students, the e-learning tutor and two researchers from one of the support centers in four forums of the discipline of Spanish III in a teacher development course in a federal university in southern Brazil in a distance learning modality. The results were obtained by descriptive analysis of a qualitative nature and of a virtual ethnographic interpretation (HINE, 2004). In the interactions we confirmed the hypothesis that there were other values at stake in qualitative changes. In addition to collaboration and autonomy, we identified other values that were common among individuals in the groups, which behaved as complex adaptive (sub)systems (SAC) in each of the four studied forums, also considered as a SAC. Taking into consideration Schwartz s (1992) propositions, we have identified exchanges of mutual benefit (PIAGET, 1973) in each group that was formed in the forums, on a map of values of common scales around values such as equality, friendship, responsibility, creativity, solidarity, among others, besides those already noticed in previous work, namely collaboration and autonomy. / A pesquisa é construída com base na tese de Vetromille-Castro (2007), na qual foi constatado que a colaboração e autonomia foram os valores que fomentaram a interação e mantiveram a coesão e emergência do grupo estudado. Entretanto, Vetromille-Castro considerou que havia outros valores, além da colaboração e da autonomia, que foram compartilhados entre os sujeitos covalorizantes (PIAGET, 1973). E é justamente a partir dessa hipótese que desenvolvemos este trabalho. Na presente pesquisa, estudamos o processo interativo em um grupo de professores em formação de Língua Espanhola como Língua Estrangeira (E/LE) nos fóruns de um ambiente virtual de aprendizagem. Analisamos as postagens de 30 alunos, da professora tutora a distância e das duas professoras pesquisadoras de um polo em quatro fóruns da disciplina de língua espanhola III de uma licenciatura em uma universidade federal no sul do Brasil, na modalidade a distância. Os resultados foram obtidos mediante a análise descritiva, de natureza qualitativa e de interpretação etnográfica virtual (HINE, 2004). Nas interações confirmamos a hipótese de que havia outros valores em jogo nas trocas qualitativas, pois identificamos, além da colaboração e da autonomia, outros valores que eram comuns entre os indivíduos dos grupos, os quais se comportaram como um (sub)sistema adaptativo complexo (SAC) em cada um dos quatro fóruns estudados, também considerados como um SAC. A partir de Schwartz (1992), identificamos, no mapa de valores das escalas comuns de cada grupo que se formou nos fóruns, trocas de benefício recíproco (PIAGET,1973) em torno de valores, como igualdade, amizade, responsabilidade, criatividade, solidariedade, dentre outros, além daqueles já percebidos em pesquisa anterior, a saber, colaboração e autonomia.

L'augmentation exponentielle du nombre d'images nécessite des moyens efficaces pour les classer en fonction de leur contenu visuel. Le sac de mot visuel (Bag-Of-visual-Words, BOW), en raison de sa simplicité et de sa robustesse, devient l'approche la plus populaire. Malheureusement, cette approche ne prend pas en compte de l'information spatiale, ce qui joue un rôle important dans les catégories de modélisation d'image. Récemment, Lazebnik ont introduit la représentation pyramidale spatiale (Spatial Pyramid Representation, SPR) qui a incorporé avec succès l'information spatiale dans le modèle BOW. Néanmoins, ce système de correspondance rigide empêche la SPR de gérer les variations et les transformations d'image. L'objectif principal de cette thèse est d'étudier un modèle de chaîne de correspondance plus souple qui prend l'avantage d'histogrammes de BOW locaux et se rapproche de la correspondance de la chaîne. Notre première contribution est basée sur une représentation en chaîne et une nouvelle distance d'édition (String Matching Distance, SMD) bien adapté pour les chaînes de l'histogramme qui peut calculer efficacement par programmation dynamique. Un noyau d'édition correspondant comprenant à la fois d'une pondération et d'un système pyramidal est également dérivée. La seconde contribution est une version étendue de SMD qui remplace les opérations d'insertion et de suppression par les opérations de fusion entre les symboles successifs, ce qui apporte de la souplesse labours et correspond aux images. Toutes les distances proposées sont évaluées sur plusieurs jeux de données tâche de classification et sont comparés avec plusieurs approches concurrentes / The exponential increasing of the number of images requires efficient ways to classify them based on their visual content. The most successful and popular approach is the Bag of visual Word (BoW) representation due to its simplicity and robustness. Unfortunately, this approach fails to capture the spatial image layout, which plays an important roles in modeling image categories. Recently, Lazebnik et al (2006) introduced the Spatial Pyramid Representation (SPR) which successfully incorporated spatial information into the BoW model. The idea of their approach is to split the image into a pyramidal grid and to represent each grid cell as a BoW. Assuming that images belonging to the same class have similar spatial distributions, it is possible to use a pairwise matching as similarity measurement. However, this rigid matching scheme prevents SPR to cope with image variations and transformations. The main objective of this dissertation is to study a more flexible string matching model. Keeping the idea of local BoW histograms, we introduce a new class of edit distance to compare strings of local histograms. Our first contribution is a string based image representation model and a new edit distance (called SMD for String Matching Distance) well suited for strings composed of symbols which are local BoWs. The new distance benefits from an efficient Dynamic Programming algorithm. A corresponding edit kernel including both a weighting and a pyramidal scheme is also derived. The performance is evaluated on classification tasks and compared to the standard method and several related methods. The new method outperforms other methods thanks to its ability to detect and ignore identical successive regions inside images. Our second contribution is to propose an extended version of SMD replacing insertion and deletion operations by merging operations between successive symbols. In this approach, the number of sub regions ie. the grid divisions may vary according to the visual content. We describe two algorithms to compute this merge-based distance. The first one is a greedy version which is efficient but can produce a non optimal edit script. The other one is an optimal version but it requires a 4th degree polynomial complexity. All the proposed distances are evaluated on several datasets and are shown to outperform comparable existing methods.

Orientador: Lúcia Regina Durrant / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-22T11:02:32Z (GMT). No. of bitstreams: 1 Pescumo_FernandaFranzoni_M.pdf: 1387373 bytes, checksum: baa6cd7b83f29182ab90172ebb03c248 (MD5) Previous issue date: 2013 / Resumo: Biossurfactantes e bioemulsificantes são compostos ativos de superfícies (CAS) produzidos por micro-organismos. Desempenham várias funções biológicas, e sua característica anfifílica, juntamente com baixa toxicidade, biodegradabilidade e resistência a extremos de pH, temperatura e salinidade, tem despertado o interesse para a aplicação dessas moléculas em processos biotecnológicos. Porém, o alto custo aliado à baixa produção ainda são impedimentos para a utilização em larga escala. Os desafios para se implementar a produção são: desenvolvimento de estratégias para tornar a produção economicamente viável e o isolamento de moléculas e microorganismos mais eficientes. Neste trabalho, foi estudada a produção, isolamento, extração e caracterização de um CAS por Gordonia amicalis. O micro-organismo foi cultivado em meio GYP (glucose, extracto de levedura, peptona) por 7 dias, e a extração foi feita por precipitação com sulfato de amônio, que resultou em uma concentração de 0,5 g/L do extrato bruto em meio líquido. O CAS não reduziu significativamente a tensão superficial do meio GYP, e apresentou um balanço hidrofílico-lipofílico (HBL) de caráter lipofílico, apresentando mais emulsões do tipo água em óleo (A/O) do que óleo em água (O/A). A molécula apresentou estabilidade a temperaturas de 25ºC a 100ºC, pH de 2 a 10 e salinidades de 5% a 15% quando cultivado por 7 dias, e foi capaz de modificar a interface água/superfície na análise de ângulo de contato. O extrato de 14 dias apresentou Atividade Emulsificante em 24 horas (AE24) reduzida em temperaturas acima de 50ºC, e ausente em pH ácido e salinidades de 5% e 10%. Análises de Cromatografia de Camada Delgada (CCD) revelaram presença de aminoácidos e açúcares na molécula e a análise do potencial zeta revelou que o CAS é um surfactante aniônico. Nas análises de Espectrometria no Infravermelho com Transformadas de Fourier (IR-TF) foram observados estiramentos indicativos de agrupamentos O-H e C-O, que podem indicar presença de grupos éter ou ésteres. O CAS produzido por Gordonia amicalis em meio sintético GYP mostrou-se um eficiente agente emulsificante, com potencial para aplicações biotecnológicas futuras / Abstract: Biosurfactants and bioemulssifiers are surface active compounds (SACs) produced by microorganisms. They have a wide variety of biological functions. Its amphiphilic characteristic, with low toxicity, biodegradability and resistance to extremes of pH, temperature and salinity, has increased the interest of these molecules for application biotechnological process. However, high costs and low production rates are restrictions to their widespread use. The challenges for implementing production are: developing strategies to turn the production economically feasible and isolating more efficient molecules and microorganisms. In this work, we studied the production, isolation, extraction and characterization of a SAC by a Gordonia amicalis. The microrganism was grown in GYP (Glucose, Yeast extract, Peptone) medium for 7 days, and the isolation was carried out by precipitation with ammonium sulfate, which resulted in 0.5 g / L of crude extract. The SAC did not significantly reduce the surface tension of GYP medium, and showed an hydrophilic-lipophilic balance (HLB) with lipophilic character, showing more water in oil (W/O) emulsions than oil in water (O/W) emulsions. The molecule extracted at 7 days was stable at temperatures ranging from 25 to 100 ° C, pH of 2-10 and salinities of 5-15%, and can modify the water/surface contact by the angle of contact analysis. The 14-day isolated extract showed EA24 reduced at temperatures above 50 ºC, and had no Emulsification Activity in 24 hours (EA24) in acid pH and salinity of 5% and 10%. Thin Layer Chromatography (TLC) analysis revealed the presence of sugars and amino acids in the molecule and the zeta potential analysis revealed the compound is an anionic surfactant. In the Fourier Transformed Infrared Spectrometry (FTIV) it were observed stretches indicatives of O-H and C-O groups, that might indicate ether or ester groups. The SAC produced by Gordonia amicalis in GYP medium proved to be an efficient emulsifier, with potential for biotechnological applications / Mestrado / Ciência de Alimentos / Mestra em Ciência de Alimentos

Structured Academic Controversy (SAC) är en internationellt beprövad metod för att bedriva deliberativa samtal om samhällsfrågor i skolan. SAC har dock inte beforskats i svensk kontext tidigare. Examensarbetet syftar till att få kunskap om högstadielärares erfarenheter av den deliberativa diskussionsmodellen SAC i ämnet samhällskunskap. Studien bör förstås i relation till att utreda SAC:s möjligheter, utmaningar och problem som didaktisk metod i ämnetsamhällskunskap och SAC:s potential i förhållande till läroplanens övergripande mål och riktlinjer. Empirin har samlats in genom intervjuer med två lärare som testat SAC efter vårt lektionsupplägg i totalt fem klasser. Resultatet visar att SAC kan vara en lämplig metod i samhällskunskapsundervisningen, då den potentiellt utvecklar ämnesspecifika förmågor och kunskaper samt ett bättre samtalsklimat och ett ökat elevdeltagande. Den största utmaningen med metoden är lärarnas brist på tid ur olika aspekter. Främst gäller det lärarnas behov av tid till förberedelse samt bristen på undervisningstid.

Les soins parentaux sont observés dans de nombreux taxons et sont exprimés de façon plus ou moins complexe. L’étude de ces comportements chez les arthropodes, en particulier chez les araignées, nous permet de mieux comprendre comment les soins à la progéniture se sont mis en place au cours de l’évolution. Au cours de cette thèse nous avons étudié le comportement d’une espèce errante Pardosa saltans (Lycosidae) vis-à-vis de son cocon, puis de ses jeunes. Nous avons décrit les comportements manifestés par la mère pendant toute la période de soin au cocon (période de développement embryonnaire et postembryonnaire des jeunes). Notre étude a permis de mettre en évidence qu’il existe une ontogenèse comportementale dans le cadre des soins parentaux chez cette espèce. Elle a permis également d’évaluer les dépenses énergétiques subies par la mère pendant cette période. Et enfin nous avons identifié, pour la première fois, les composés chimiques présents à la surface du cocon. Nos expériences montrent que ces composés chimiques associés aux vibrations émises par les juvéniles à l’intérieur du cocon sont utilisés par la mère détecter l’état de développement de sa progéniture. / Parental care is widespread among animal kingdom and is more or less expressed. Thus, the study of these behaviours among primitive species, can let us understand how parental behaviours were implemented during evolution. In this thesis we studied maternal behaviour in a wandering spider Pardosa saltans (Lycosidae) with her egg-sac and her young which she actively transports. We have described maternal behaviour towards the egg-sac and highlighted the presence of ontogeny of maternal behavior in this species. Furthermore, we were able to evaluate some of the physiological and ecological investment associated with maternal care of the egg-sac and young. Finally, we have, for the first time, identify chemical compounds on the surface of the silk egg-sac, and placed in evidence the presence of a chemical and vibrational communication between the mother and her cocoon.

La gestión logística se ha convertido en la estrategia más idónea para mejorar la eficiencia y eficacia de las empresas, así como contribuir a mejorar su competitividad. En el Perú los costos logísticos comprenden una considerable proporción del precio final dependiendo del producto y supera en más del doble al que tiene otros países de Sudamérica. La necesidad de llevar a cabo esta investigación surge dado que existen pérdidas económicas y de tiempo en la Agrícola Cerro Prieto, causado por una mala gestión de documentos logísticos, ocasionado por contar con un sistema ERP (escritorio) rudimentario, que no facilita la priorización de documentos logísticos el cual está sometido a todas las desventajas de un Sistema de Información de escritorio dentro de una red corporativa, con procesos no alineados a los requerimientos organizacionales. En esta investigación se plantea una solución utilizando un algoritmo priorización para apoyar la gestión de cambios de estado de los documentos logísticos del ERP Nisira en la Agrícola Cerro Prieto SAC. Lo cual conlleva a realizar el análisis de la situación problemática relacionada con la pérdida de tiempo estratégico (gerencias y jefaturas de área) en el momento de aprobar, rechazar o dar visto bueno a un documento logístico; puesto que no es posible gestionarlos de forma masiva es decir más de uno a la vez. Como también no es posible la gestión fuera de la red corporativa de la empresa, para lo cual se ha planteado la siguiente hipótesis: El desarrollo de una aplicación móvil permitirá optimizar la gestión de documentos logísticos en la Agrícola Cerro Prieto SAC El objetivo general de esta investigación es: Optimizar la gestión de documentos logísticos en la Agrícola Cerro Prieto SAC, mediante el desarrollo de una aplicación móvil. Los objetivos específicos son los siguientes: Disminuir el tiempo de gestión de un documento logístico. Disminuir el tiempo de búsqueda de un documento logístico en el ERP Nisira. Aumentar el índice de documentos logísticos que llegan a su estado final el día de su creación. Disminuir el ratio de materiales sin rotación en almacén. Para la recolección de información se hizo uso de las técnicas conocidas como entrevistas y encuestas, como medios para poder extraer información y posteriormente ser procesada para su interpretación, y poder medir esta realidad problemática apoyado en la aplicación del algoritmo de optimización por enjambre de partículas.

Polypyrimidine-tract binding protein 1 (PTBP1) is an important cellular regulator of messenger RNAs influencing the alternative splicing profile of a cell as well as its mRNA stability, location and translation. In addition, it is diverted by some viruses to facilitate their replication. Here, we used a novel PTBP1 knockout mouse to analyse the tissue expression pattern of PTBP1 as well as the effect of its complete removal during development. We found evidence of strong PTBP1 expression in embryonic stem cells and throughout embryonic development, especially in the developing brain and spinal cord, the olfactory and auditory systems, the heart, the liver, the kidney, the brown fat and cartilage primordia. This widespread distribution points towards a role of PTBP1 during embryonic development. Homozygous offspring, identified by PCR and immunofluorescence, were able to implant but were arrested or retarded in growth. At day 7.5 of embryonic development (E7.5) the null mutants were about 5x smaller than the control littermates and the gap in body size widened with time. At mid-gestation, all homozygous embryos were resorbed/degraded. No homozygous mice were genotyped at E12 and the age of weaning. Embryos lacking PTBP1 did not display differentiation into the 3 germ layers and cavitation of the epiblast, which are hallmarks of gastrulation. In addition, homozygous mutants displayed malformed ectoplacental cones and yolk sacs, both early supportive structure of the embryo proper. We conclude that PTBP1 is not required for the earliest isovolumetric divisions and differentiation steps of the zygote up to the formation of the blastocyst. However, further post-implantation development requires PTBP1 and stalls in homozygous null animals with a phenotype of dramatically reduced size and aberration in embryonic and extra-embryonic structures.

Dans cette étude, la stabilité de préparations intraveineuses de cyclosporine (0.2 et 2.5 mg/mL dans NaCl 0.9% ou dextrose 5%) entreposées dans des seringues de polypropylène, des sacs de polypropylène-polyoléfine et des sacs de vinyle acétate d’éthylène a été évaluée. Une méthode HPLC indicatrice de la stabilité à base de méthanol a été développée et validée suite a des études de dégradation forcée. Les solutions évaluées ont été préparées de façon aseptique, puis entreposées à 25°C. La stabilité chimique a été évaluée par HPLC et la stabilité physique a été évaluée par inspection visuelle et aussi par diffusion dynamique de la lumière (DLS). Tous les échantillons sont demeurés stables chimiquement et physiquement dans des sacs de polypropylène-polyoléfine (>98% de cyclosporine récupérée après 14 jours). Lorsqu’entreposés dans des seringues de polypropylène, des contaminants ont été extraits des composantes de la seringue. Toutefois, aucune contamination n’a été observée après 10 min de contact entre la préparation de cyclosporine non-diluée et ces mêmes seringues. Les préparations de 2.5 mg/mL entreposées dans des sacs de vinyle acétate d’éthylène sont demeurés stables chimiquement et physiquement (>98% de cyclosporine récupérée après 14 jours). Toutefois, une adsorption significative a été observée avec les échantillons 0.2 mg/mL entreposés dans des sacs de vinyle acétate d’éthylène (<90% de cyclosporine récupéré après 14 jours). Une étude cinétique a démontré une bonne corrélation linéaire entre la quantité adsorbée et la racine carrée du temps de contact (r2 > 0.97). Un nouveou modèle de diffusion a été établi. En conclusion, les sacs de polypropylène-polyoléfine sont le meilleur choix; les seringues de polypropylène présentent un risque de contamination, mais sont acceptables pour un transfert rapide. Les sacs de vinyle acétate d’éthylène ne peuvent être recommandés à cause d’un problème d’adsorption. / In the present study, the stability of intravenous cyclosporine preparations (0.2 and 2.5 mg/mL in 0.9% sodium chloride injection or 5% dextrose injection) stored in polypropylene (PP) syringes, polypropylene–polyolefin (PP-PO) bags and ethylene vinyl acetate (EVA) bags was evaluated. A methanol-based high-performance liquid chromatography (HPLC) method was developed and validated to be stability-indicating by stress degradation tests. The test solutions were aseptically prepared and stored at 25 °C. Chemical stability was evaluated by HPLC assay. Physical stability was assessed by visual inspection and a dynamic light scattering (DLS) method. All samples were chemically stable (> 98% of recovered cyclosporine) and physically stable when stored in polypropylene–polyolefin bags for 14 days. When stored in polypropylene syringes, some impurities were leached. However, no leaching was detected when the syringes were exposed to undiluted intravenous cyclosporine for 10 minutes. The preparations of 2.5 mg/mL were chemically and physically stable as stored in ethylene vinyl acetate bags for a period of 14 days (> 98% of recovered cyclosporine), while significant cyclosporine adsorption occurred on the samples of 0.2 mg/mL (< 90 % of recovered cyclosporine) after 14 days. Kinetic study showed that good linear correlations were achieved by plotting the adsorption amount versus square root of contact time (r2 > 0.97). A novel diffusion model was established and successfully predicted long-term drug stability. In conclusion, polypropylene–polyolefin bags were the best choice; syringes were inferior because of leachables. However, they were safe for preparation and transferring undiluted intravenous cyclosporine. Ethylene vinyl acetate bags cannot be recommended due to cyclosporine adsorption.

Dans cette thèse, nous nous intéressons à l'étude des capacités de la méta heuristique d'optimisation par colonie de fourmis (Ant Colony Optimization - ACO) pour résoudre des problèmes d’optimisation combinatoire multi-objectif. Dans ce cadre, nous avons proposé une taxonomie des algorithmes ACO proposés dans la littérature pour résoudre des problèmes de ce type. Nous avons mené, par la suite, une étude expérimentale de différentes stratégies phéromonales pour le cas du problème du sac à dos multidimensionnel mono-objectif. Enfin,nous avons proposé un algorithme ACO générique pour résoudre des problèmes d'optimisation multi-objectif. Cet algorithme est paramétré par le nombre de colonies de fourmis et le nombre de structures de phéromone considérées. Il permet de tester et de comparer, dans un même cadre,plusieurs approches. Nous avons proposé six variantes de cet algorithme dont trois présentent de nouvelles approches et trois autres reprennent des approches existantes. Nous avons appliqué et comparé ces variantes au problème du sac à dos multidimensionnel multi-objectif / In this thesis, we investigate the capabilities of Ant Colony Optimization (ACO) metaheuristic to solve combinatorial and multi-objective optimization problems. First, we propose a taxonomy of ACO algorithms proposed in the literature to solve multi-objective problems. Then, we studydifferent pheromonal strategies for the case of mono-objective multidimensional knapsackproblem. We propose, finally, a generic ACO algorithm to solve multi-objective problems. Thisalgorithm is parameterised by the number of ant colonies and the number of pheromonestructures. This algorithm allows us to evaluate and compare new and existing approaches in thesame framework. We compare six variants of this generic algorithm on the multi-objectivemultidimensional knapsack problem

Altas taxas de mortalidade embrionária ocorrem no período de implantação em embriões provenientes de IATF e FIV. Acredita-se que a falha no desenvolvimento do saco vitelino possa estar relacionada com estas perdas embrionárias. O objetivo deste trabalho foi descrever as características macroscópicas, microscópicas e expressão gênica do processo de involução do saco vitelino, visto que os dados da literatura são contraditórios ao descrever os processos de formação e involução do saco vitelino em embriões provenientes de IATF e FIV. Foram utilizados 19 embriões de IATF e 16 de FIV, provenientes da Sociedade Agropecuária Imaculada Conceição-Redenção/PA, Brasil. Observou-se que não houve diferença significativa no tamanho dos embriões nas idades de 25 (p=0,1), 35 (p=0,1), 40 (p=0,4) e 45 (p=0,36) dias, quando comparados os grupos de IATF e FIV. Entretanto entre os embriões de IATF e FIV com 30 dias de gestação, apresentaram diferença estatística (p= 0,03). A curva de crescimento (Crow-Rump) aumentou gradativamente e linearmente em função da idade gestacional. Macroscopicamente, observou-se que aos 25 dias de gestação, o saco vitelino apresentava formato de T e coloração translúcida. Uma porção central se encontrava próxima a região ventral do embrião emitindo duas extremidades que eram finas membranas, estas acompanhavam o alantóide juntamente com os vasos umbilicais. Aos 30 a 35 dias, apresentava coloração amarelada, sua parte central e extremidades bem diminuídas mostrando sinais de um início de regressão. Aos 40 a 45 dias, o seu processo de involução estava caracterizado, com extremidades enoveladas e região central assemelhando-se a um pequeno grão achatado que se encontrava em contato com o âmnio. Microscopicamente, o saco vitelino era formado por três camadas: o endoderma, camada única que reveste a cavidade vitelínica, uma camada intermediária mesenquimal vascular e o mesotélio, camada simples voltada ao exoceloma. O epitélio do saco vitelino formava dobras ou criptas que se projetavam para a luz. Imunohistoquímica notou-se marcação para os anticorpos VEGF, Flt-1 e KDR. Observou-se que não houve diferença significativa na expressão do mRNA do VEGF, KDR e Flt-1 entre os grupos e nas idades gestacionais analisadas, aos 30 dias notou-se uma tendência entre os grupos em relação a expressão do Flt-1. Os fatores de crescimento b FGF, FGFR-1 e FGFR-2, não apresentaram diferenças em suas expressões, somente aos 35 dias de gestação para o mRNA FGFR-1. Conclui-se que o saco vitelino está intensamente relacionado com o desenvolvimento embrionário, na qual sua involução e desaparecimento relacionam-se com o crescimento e \"maturação\" embrionária. / High mortality rates occur during embryonic implantation embryos from IVF and FTAI. It is believed that the failure in the development of the yolk sac may be related to these embryonic losses. The objective of this study was to describe the macroscopic, microscopic and mRNA expression features of the yolk sac involution process, since the literature relates contradictory information regarding the processes of formation and involution of the yolk sac in IVF and TAI embryos. Nineteen embryos were used for FTAI and 16 IVF; the specimes were obtained from the Sociedade Agropecuária Imaculada Conceição-Redenção/PA, Brazil. No significant differences were observed in the size of embryos aged 25 (p = 0.1), 35 (p = 0.1), 40 (p = 0.4) and 45 (p = 0.36) days in the groups of IVF and FTAI. However between FTAI and IVF embryos with 30 days of gestation, a difference (p = 0.03) was detectable. The growth curve (Crow-Rump) increased gradually and linearly with gestational age. Macroscopically, it was observed that after 25 days of gestation, the yolk sac was \"T-shaped\" and transparent colored. A central portion was observed in the vicinity of the ventral ends of the embryo exhibiting two thin membranes, which accompanied the allantois with the umbilical vessels. At 30 to 35 days this portion becomes yellowish and its central part together with the extremities was reduced displaying clearly signs of regression. At 40 to 45 days, the process of involution was presented in a curled fashion and ends with the central region resembling a flat small grain in contact with the amnion. Microscopically, the yolk sac was formed by three layers: the endoderm, single layer lining the vitelline cavity, an intermediate layer and vascular mesenchymal mesothelium, exoceloma focused on single layer. The epithelium of the yolk sac formed folds or crypts, which projected to the light. Immunohistochemistry marking was noted for antibodies VEGF, Flt-1 and KDR. No significant difference were observed in mRNA expression of VEGF, KDR and Flt-1 between groups and the gestational ages analyzed at 30 days there has been a trend among the groups regarding the expression of Flt-1. The growth factors bFGF, FGFR-1 and FGFR-2 showed no differences in their expressions, with the exception of 35 days of gestation for the m-RNA FGFR 1. It was concluded that the yolk sac is strongly related to embryonic development, in which the involution and disappearance are related to growth and \"maturity\" stage.