Ce travail de thèse porte sur l’étude de l’effet du traitement par champs électriques pulsés (CEP) sur l’amélioration de la congélation des tissus végétaux. Pour l’ensemble de notre étude, nous avons démontré que l’effet des champs électriques pulsés est complexe. Le prétraitement entraîne une électroperméabilisation des membranes. Les analyses calorimétriques ont mis en évidence que l’électroperméabilisation conduit à une augmentation de la teneur en eau liée. Les transferts de matière entre les milieux intra et extracellulaires sont intensifiés. Cela conduit à une modification dynamique de la composition des deux compartiments au cours de la congélation. En effet, les essais réalisés sur le cryo-pressage assisté par CEP démontrent que les températures de fusion sont plus basses et que le jus récupéré est beaucoup plus concentré. Il a été constaté que le temps de congélation d’un échantillon soumis préalablement à un prétraitement par champs électriques pulsés est sensiblement plus court que celui d’un échantillon sans prétraitement. D’autre part, l’électroperméabilisation facilite les transferts de matière avec le milieu extérieur. Le prétraitement par CEP accélère notamment l’imprégnation des tissus végétaux par des cryoprotectants, l’évaporation de l’eau libre et la sublimation de l’eau congelée. Finalement, le prétraitement par champs électriques pulsés induit des modifications de la structure des échantillons, de leur composition et influence favorablement les transferts couplés de masse et d’énergie. / This work is focused on the study of the effects of pulsed electric fields (PEF) on the improvement of plant tissues freezing. These studies have demonstrated that the effects of the PEF are rather complex. The PEF treatment results in membrane electro-permeabilization. Calorimetric analyses showed that the electro-permeabilization leads to an increase in bound water content. It also results in acceleration of mass transfer processes between intra- and extracellular parts of a tissue. The dynamic modification of the composition of these two parts during the freezing was observed. Experimental tests using the PEF-assisted cryo-pressing demonstrated that the melting temperatures were lower and that the extracted juice was much more concentrated as compared to untreated tissues. Moreover, the PEF-treatment allowed significant decreasing of freezing time. Furthermore, the electro-permeabilization facilitates the mass transfer with the external medium. The PEF treatment accelerates the impregnation of plant tissues by cryoprotectants, evaporation of free water and sublimation of frozen water. Finally, the treatment by PEF induces changes in the structure of the samples, their composition and positively influences both the mass and energy transfers.

Durante o processo de criopreservação o espermatozóide passa por mudanças estruturais nas membranas que resulta em diminuição da fertilidade. Este estudo foi realizado para comparar os efeitos de duas técnicas de congelação (técnica convencional e técnica automatizada), curvas de congelação e o uso de três crioprotetores (glicerol, etilenoglicol e dimetilformamida) sobre a motilidade, vigor e integridade das membranas espermáticas (plasmática, acrossomal e mitocondrial) do sêmen bovino. Foram utilizados cinco touros da raça Simental, coletados semanalmente por seis semanas. O semên foi avaliado e diluído em tris-gema (fração única), preparado previamente com os seguintes crioprotetores:- dimetilformamida (3%), etilenoglicol (7%) ou glicerol (7%). A metade das doses foi congelada pela técnica convencional (TC), da seguinte maneira:- seis quilogramas de gelo moído foi colocado em uma de uma caixa de isopor de 15 litros, quando então as palhetas a serem congeladas foram colocadas sobre um suporte, na posição horizontal, por 90 minutos (curva de resfriamento, -0,55°C/min). Imediatamente após, o suporte com as palhetas foi transferido para outra caixa de isopor onde as palhetas permaneceram em vapor de nitrogênio (3cm), por 15 minutos (curva de congelação, -19,1°C/min). A outra metade das palhetas foi criopreservada pela técnica automatizada (TA), utilizando-se um aparelho programável portátil de controle eletrônico (TK2000), com taxa de resfriamento de -0,23°C/minuto e taxa de congelação de -15,5°C/minuto. Após a congelação as palhetas foram mantidas em botijões criogênicos e descongeladas para avaliação da motilidade (%) e vigor (1-5) por microscopia óptica. A integridade das membranas plasmática, acrossomal e mitocondrial foi avaliada utilizando-se o iodeto de propídio (PI); aglutinina de Pisum sativum conjugada a fluoresceína (FITC-PSA) e MitoTracker Green FM (MITO), respectivamente, por microscopia de epifluorescência. As análises estatísticas foram realizadas com o auxílio do Programa StatView® (SAS Institute, Cary, NC, USA). Não houve diferenças significativas entre as técnicas e nem interação entre crioprotetor e técnica de congelação (P>0,05) para os parâmetros avaliados. Houve diferença entre os crioprotetores (P<0,05), sendo que o glicerol preservou melhor a motilidade, o vigor e a integridade das membranas plasmática, acrossomal e mitocondrial dos espermatozóides quando comparado ao etilenoglicol e a dimetilformamida. O etilenoglicol foi superior à dimetilformamida para as avaliações da motilidade e da integridade das membranas plasmática e mitocondrial (P<0,05). Uma vez que, 85% dos espermatozóides apresentaram algum grau de lesão, isto nos conduz a inferir que pesquisas são necessárias para que se obtenha melhoria nos resultados após a criopreservação do sêmen bovino / During cryopreservation, spermatozoa undergo many changes leading to membrane damage which result in decreased fertility. This study was designed to compare the effects of two freezing techniques (conventional and automated), their freezing curves and the use of three cryoprotectants (glycerol, ethylene glycol and dimethylformamide) on the motility, vigor and integrity of spermatic membranes (plasmatic, acrosomal, and mitochondrial) of bovine semen. Five Simmental bulls ranging from 24 to 36 months age were submitted one a week to semen collection for six weeks. Semen samples were evaluated and diluted in TRIS-yolk medium (one step). Each semen collection dilutors were prepared previously with each of following cryoprotectants:- glycerol (7%), ethylene glycol (7%) or dimethylformamide (3%). Half of the amount of straws (0.5 mL) was frozen by a conventional manual technique (TC), as in following protocol:- six kilograms of ground ice were placed in the bottom of a thermal box (15 L), straws were cooled on a grid placed horizontally for 90 minutes (cooling rate, -0.55°C/min), immediately transferred to another thermal box and frozen in static liquid nitrogen vapor (15 min) on the same grid placed 3 cm above the liquid nitrogen (freezing rate, -19.1°C/min). The other half of straws was frozen by automated technique (TA). TA was performed using an electronic controlled programmed machine (TK2000) which cooling rate was -0.23°C/min and freezing rate was -15.5°C/min. Straws were plunged into liquid nitrogen and stored at -196°C. The motility (%) and vigor (1-5) were assessed using optic microscopy. The integrity of plasmatic, acrosomal and mitochondrial membranes were evaluated using propidium iodide (PI), fluorescein conjugated Pisum sativum agglutinin (FITC-PSA) and MitoTracker Green FM (MITO), respectively, by fluorescence microscopy. Effects of treatment were analyzed by StatView® Program, (SAS Institute, Cary, NC, USA). There were no significant differences (P>0.05) between the two freezing techniques and no interaction among cryoprotectant and freezing techniques for all assessed parameters. Glycerol showed better results (P<0.05) than other two cryoprotectants for motility, vigor, and integrity of plasmatic, acrosomal and mitocondrial membranes. Ethylene glycol was superior (P<0.05) than dimethylformamide in preserve motility, and integrity of plasmatic and mitochondrial membranes. Because 85% of spermatozoa showed some kind of post thawing injury, further studies are required to improve cryopreservation techniques used routinely for bovine semen

Orientador: Alexandre Ninhaus Silveira / Resumo: A criopreservação é uma tecnologia empregada para preservação de células, tecidos e embriões em baixas temperaturas. Para o desenvolvimento de tal tecnologia para a preservação seminal, é necessário o conhecimento sobre as características seminais da espécie que se pretende trabalhar, o estabelecimento de soluções diluentes que protegerão as células espermáticas e, dos respectivos protocolos de resfriamento, congelamento e descongelamento do sêmen criopreservado. As soluções crioproteroras devem ser atóxicas às células espermáticas, mantendo as características do fluido seminal. Assim, este trabalho teve por objetivos além de conhecer as características seminais do sêmen de Astyanax altiparanae, desenvolver um protocolo eficiente para a criopreservação seminal da espécie e sua utilização posterior. Para isso, exemplares adultos e maduros de A. altiparanae foram induzidos hormonalmente à reprodução com Ovopel®, sendo o sêmen coletado após 226 horas-grau em com auxílio de micropipetas. Deste foram avaliadas as características seminais como, osmolalidade, concentração espermática, motilidade espermática subjetiva e motilidade objetiva e vários outros aspectos de cinética dos espermatozoides pelo uso do CASA (Integrated Semen Analysis System). Foram avaliadas dez soluções crioprotetoras compostas por três bases diluentes A (5% de glicose + 10% gema de ovo), B (Bestville Thawing Solution (BTS®) a 5%) e C (5% de glicose), combinadas com um crioprotetor interno dimetilsulfóxido ou m... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Cryopreservation is a technology used to preserve cells, tissues and embryos at low temperatures. For the development of such seminal preservation technology, it is necessary to know the seminal characteristics of the species to be worked on, the establishment of diluent solutions that will protect the sperm cells, and the respective protocols of cooling, freezing and thawing of the cryopreserved semen. Cryoprotective solutions should be non-toxic to sperm cells, while maintaining seminal fluid characteristics. Thus, this work had as objectives besides knowing the seminal characteristics of Astyanax altiparanae, to develop an efficient protocol for the seminal cryopreservation of the species for its later use. For this, adult and mature A. altiparanae specimens were hormonally induced to Ovopel® reproduction, and the semen was collected after 226 hours-degree with the help of micropipettes. Seminal characteristics such as osmolality, sperm concentration, subjective sperm motility and objective motility, and several other aspects of sperm kinetics were evaluated using CASA (Integrated Semen Analysis System). Ten cryoprotectant solutions composed of three diluent bases A (5% glucose + 10% egg yolk), B Bestville Thawing Solution (BTS®) 5% and C (5% glucose), combined with a cryoprotectant internal dimethylsulfoxide or methylglycol, in concentrations of 10% and 15%. The efficiency of these solutions was evaluated by the analysis of the computerized sperm motility. For cryopreserv... (Complete abstract click electronic access below) / Mestre

Durante o processo de criopreservação o espermatozóide passa por mudanças estruturais nas membranas que resulta em diminuição da fertilidade. Este estudo foi realizado para comparar os efeitos de duas técnicas de congelação (técnica convencional e técnica automatizada), curvas de congelação e o uso de três crioprotetores (glicerol, etilenoglicol e dimetilformamida) sobre a motilidade, vigor e integridade das membranas espermáticas (plasmática, acrossomal e mitocondrial) do sêmen bovino. Foram utilizados cinco touros da raça Simental, coletados semanalmente por seis semanas. O semên foi avaliado e diluído em tris-gema (fração única), preparado previamente com os seguintes crioprotetores:- dimetilformamida (3%), etilenoglicol (7%) ou glicerol (7%). A metade das doses foi congelada pela técnica convencional (TC), da seguinte maneira:- seis quilogramas de gelo moído foi colocado em uma de uma caixa de isopor de 15 litros, quando então as palhetas a serem congeladas foram colocadas sobre um suporte, na posição horizontal, por 90 minutos (curva de resfriamento, -0,55°C/min). Imediatamente após, o suporte com as palhetas foi transferido para outra caixa de isopor onde as palhetas permaneceram em vapor de nitrogênio (3cm), por 15 minutos (curva de congelação, -19,1°C/min). A outra metade das palhetas foi criopreservada pela técnica automatizada (TA), utilizando-se um aparelho programável portátil de controle eletrônico (TK2000), com taxa de resfriamento de -0,23°C/minuto e taxa de congelação de -15,5°C/minuto. Após a congelação as palhetas foram mantidas em botijões criogênicos e descongeladas para avaliação da motilidade (%) e vigor (1-5) por microscopia óptica. A integridade das membranas plasmática, acrossomal e mitocondrial foi avaliada utilizando-se o iodeto de propídio (PI); aglutinina de Pisum sativum conjugada a fluoresceína (FITC-PSA) e MitoTracker Green FM (MITO), respectivamente, por microscopia de epifluorescência. As análises estatísticas foram realizadas com o auxílio do Programa StatView® (SAS Institute, Cary, NC, USA). Não houve diferenças significativas entre as técnicas e nem interação entre crioprotetor e técnica de congelação (P>0,05) para os parâmetros avaliados. Houve diferença entre os crioprotetores (P<0,05), sendo que o glicerol preservou melhor a motilidade, o vigor e a integridade das membranas plasmática, acrossomal e mitocondrial dos espermatozóides quando comparado ao etilenoglicol e a dimetilformamida. O etilenoglicol foi superior à dimetilformamida para as avaliações da motilidade e da integridade das membranas plasmática e mitocondrial (P<0,05). Uma vez que, 85% dos espermatozóides apresentaram algum grau de lesão, isto nos conduz a inferir que pesquisas são necessárias para que se obtenha melhoria nos resultados após a criopreservação do sêmen bovino / During cryopreservation, spermatozoa undergo many changes leading to membrane damage which result in decreased fertility. This study was designed to compare the effects of two freezing techniques (conventional and automated), their freezing curves and the use of three cryoprotectants (glycerol, ethylene glycol and dimethylformamide) on the motility, vigor and integrity of spermatic membranes (plasmatic, acrosomal, and mitochondrial) of bovine semen. Five Simmental bulls ranging from 24 to 36 months age were submitted one a week to semen collection for six weeks. Semen samples were evaluated and diluted in TRIS-yolk medium (one step). Each semen collection dilutors were prepared previously with each of following cryoprotectants:- glycerol (7%), ethylene glycol (7%) or dimethylformamide (3%). Half of the amount of straws (0.5 mL) was frozen by a conventional manual technique (TC), as in following protocol:- six kilograms of ground ice were placed in the bottom of a thermal box (15 L), straws were cooled on a grid placed horizontally for 90 minutes (cooling rate, -0.55°C/min), immediately transferred to another thermal box and frozen in static liquid nitrogen vapor (15 min) on the same grid placed 3 cm above the liquid nitrogen (freezing rate, -19.1°C/min). The other half of straws was frozen by automated technique (TA). TA was performed using an electronic controlled programmed machine (TK2000) which cooling rate was -0.23°C/min and freezing rate was -15.5°C/min. Straws were plunged into liquid nitrogen and stored at -196°C. The motility (%) and vigor (1-5) were assessed using optic microscopy. The integrity of plasmatic, acrosomal and mitochondrial membranes were evaluated using propidium iodide (PI), fluorescein conjugated Pisum sativum agglutinin (FITC-PSA) and MitoTracker Green FM (MITO), respectively, by fluorescence microscopy. Effects of treatment were analyzed by StatView® Program, (SAS Institute, Cary, NC, USA). There were no significant differences (P>0.05) between the two freezing techniques and no interaction among cryoprotectant and freezing techniques for all assessed parameters. Glycerol showed better results (P<0.05) than other two cryoprotectants for motility, vigor, and integrity of plasmatic, acrosomal and mitocondrial membranes. Ethylene glycol was superior (P<0.05) than dimethylformamide in preserve motility, and integrity of plasmatic and mitochondrial membranes. Because 85% of spermatozoa showed some kind of post thawing injury, further studies are required to improve cryopreservation techniques used routinely for bovine semen

Les nombreuses pressions naturelles et anthropiques qui pèsent sur les écosystèmes coralliens font craindre leur disparition pour les années futures. Parmi les mesures de conservation, la cryoconservation permet de maintenir en sécurité les échantillons sur le long terme et à coût réduit. Les premiers travaux sur la cryoconservation des Anthozoaires incitent à développer davantage la méthode de vitrification plutôt que la congélation lente. Dans ce contexte, cette thèse propose d'expérimenter la technique de vitrification sur plusieurs formes pluricellulaires dont les apex, les planulae, les polypes primaires, les polypes isolés et les balles tissulaires (TB), toutes issues du Scléractiniaire Pocillopora damicornis. Les meilleurs résultats ont été produits avec les TB obtenues après exposition à une solution de KSW puis traitées selon la méthode V Cryo-plate. L'éthylène glycol (EG) s'est avéré le cryoprotecteur (CPA) le mieux toléré jusqu'à 4.0 M pendant 20 min à température ambiante (RT). Les mélanges binaires et ternaires de CPA ont cependant permis d'obtenir de meilleures tolérances des TB qu'avec les solutions individuelles. L'utilisation de solutions successives a permis d'obtenir des survies jusqu'à 4.5 M selon le protocole : 1.5 M EG + 0.5 M Glycérol (Gly) (5 min, RT) puis 1.5 M DMSO + 1.5 M EG + 1.5 M Gly (10 min, 0°C) et enfin 1.5 M EG + 0.5 M Gly (5 min, RT). L'intégrité des cellules épithéliales de l'ectoderme apparaît essentielle au maintien des TB durant et après les traitements. Si le protocole de vitrification n'a pu être mis au point, en revanche, l'utilisation des TB à des fins de cryoconservation apparaît très intéressante pour de futures investigations. / Numerous environmental and anthropic pressures threaten reef ecosystems, rising concerns on species loss in coming years. Among conservation measures, cryopreservation ensures the safe and cost-effective long-term conservation of biological material. The first publications focusing on Anthozoa cryopreservation reported that the vitrification approach was preferable to the slow-cooling approach. In this context, this thesis aimed at investigating a vitrification technique with several pluricellular forms of the Scleractinian Pocillopora damicornis including apexes, planulae, primary polyps, isolated polyps and tissue balls (TB). The best results were obtained using TBs produced by exposing coral branches to a KSW solution. TBs were cryopreserved using the V Cryo-plate method. The highest TB tolerance was obtained after exposure to solution containing ethylene glycol (EG) concentrated to 4.0 M for 20 min at room temperature (RT). Binary and ternary cryoprotectant (CPA) solutions were better tolerated by TBs compared with individual cryoprotectant solutions. Exposure of TBs to a series of cryoprotectant solutions with progressively increased concentration allowed obtaining TB tolerance to cryoprotectant with a concentration of 4.5 M with: 1.5 M EG + 0.5 M Glycerol (Gly) (5 min, RT), 1.5 M DMSO + 1.5 M EG + 1.5 M Gly (10 min, 0°C) and then 1.5 M EG + 0.5 M Gly (5 min, RT). Epithelial cells from the ectoderm were essential to maintain TB integrity during and following CPA treatments. Successful cryopreservation was not achieved in this work; however, it demonstrated that the use of TBs constitutes a promising way for further cryopreservation research.

No description available.

Chicken dark meat has been considered as a major underutilized commodity due to the increasing demand for further processed breast meat products. Alkali aided protein extraction is an option to increase the utilization of chicken dark meat. First, the effect of pH (10.5-12.0) on alkaline extraction of chicken dark meat has been studied, and protein yield, composition, color, and TBARs of the extracted meat have been determined. Second, textural and rheological properties and water holding capacity (WHC) of alkali extracted chicken dark meat have been evaluated. The highest protein yield (94.2%) was obtained at pH 12.0. Lipid content of the extracted meat decreased by 50% compared to chicken dark meat. WHC, hardness and chewiness of extracted meat were greater at higher pH. The gel from recovered meat with added cryoprotectants showed more stability. This process may offer the possibility to use the underutilized poultry resources for preparation of functional foods. / Food Science and Technology

Key to the success of natural and engineered tissues becoming clinically available until needed is their long-term storage at low temperatures. This can be implemented by means of freezing or vitrification. To this end, vitrification offers an attractive approach for tissue banking by forming an amorphous glass both intra- and extracellularly and thereby avoiding the harmful effects of ice formation. Generally, high concentrations of cryoprotectants (CPAs) are used in conjunction with high cooling and warming rates to achieve this. However, hurdles associated with applying this technique include the ability to adequately deliver and remove CPAs due to cellular osmotic and cytotoxic effects as well as achieving adequate cooling and warming rates throughout the tissue to avoid ice formation. The aim of this work was to account for these factors in designing cryopreservation protocols for native and engineered tissues that had intrinsically different characteristics, including tissue size and extracellular matrix properties. The tissues investigated were two types of three-dimensional, cell encapsulated systems consisting of murine insulinomas and murine embryonic stem cells, and native articular cartilage. A mathematical 3-D CPA transport model was developed to predict cell volume excursions and intracellular CPA equilibration and applied to cryopreserve an engineered tissue. This thesis established a systematic methodology to design cryopreservation protocols using experimental measurements and a mathematical model for tissues.

Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2017-03-22T14:51:38Z No. of bitstreams: 1 AlanaAB_DISSERT.pdf: 4740716 bytes, checksum: e3666ea7a25906742164df387e99208b (MD5) / Made available in DSpace on 2017-03-22T14:51:38Z (GMT). No. of bitstreams: 1 AlanaAB_DISSERT.pdf: 4740716 bytes, checksum: e3666ea7a25906742164df387e99208b (MD5) Previous issue date: 2016-11-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The cryopreservation of somatic tissue derived from collared peccaries represents an interesting step in the obtainment and conservation of cells for nuclear transfer (cloning). In this sense, tissue vitrification protocols need to be optimized to ensure maximum preservation of viable cell characteristics. Therefore, the aims of this study were to characterize histologically the peripheral auricular integumentary system (Stage 1) and evaluate different cryoprotectants in the solid-surface vitrification of somatic tissue of collared peccaries (Stage 2). Thun, ear fragments (9.0 mm3) were collected of sixteen animals derived from the Multiplication Center of Wild Animals (CEMAS/UFERSA). In the first stage, tissue samples were evaluated for the characterization of layers, its components and proliferative activity. For the second stage, tissue fragments were cryopreserved by solidsurface vitrification using Dulbecco modified minimum essential medium supplemented with 10% fetal bovine serum and different cryoprotectants and concentrations [dimethylsulfoxide (DMSO, 3.0 M), ethylene glycol (EG; 3.0 M) and association DMSO/EG (1.5 M; 1.5 M) in the absence and presence of sucrose (0.25M)]. After two weeks, warmed and non-vitrified (control) fragments were analyzed using histological techniques. Thus, for both steps, tissue samples were evaluated using hematoxylin-eosin and Gomori Trichrome, quantification of regions argyrophilic nucleolar organizer (AgNORs) and viability by MTT assay (3-[4,5- dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide). Also, in the first stage, fragments were analyzed by transmission electronic microscopy. Thus, in the first stage, sizes of 104.2 μm and 222.6 μm were observed in the epidermis and dermis, with a volumetric ratio of 36.6% and 58.7%, respectively. Moreover, in the epidermis were evidenced the basal layer (22.5 μm), intermediate (53.5 μm) and cornea (28.2 μm), with mean values of 65.3 epithelial cells, 43.4 melanocytes and 14.8 perinuclear halos. Already the dermis has 127 fibroblasts with 2.5 AgNORs by nucleolus. Additionally, the metabolic activity was 0.243. In the second stage, the 3.0 M EG with sucrose was able to maintain normal tissue characteristics compared with non-vitrified (control), especially for the volumetric ratio of epidermis (61.2 vs. 58.7) and dermis (34.5 vs. 36.6), number of fibroblast (90.3 vs. 127.0), and AgNOR ratio (0.09 vs. 0.17), respectively. In conclusion, the peripheral auricular integumentary system derived from collared peccaries possessed some variations compared to other mammals, as the number of layers and thickness of the epidermis, number of epithelial cells, melanocytes and proliferative parameters. Moreover, 3.0 M EG with 0.25 M sucrose resulted in a better cryoprotectant composition in the vitritification for somatic tissue of collared peccaries / A criopreservação de tecido somático de catetos representa uma etapa interessante na obtenção e conservação de células para a transferência nuclear (clonagem). Nesse sentido, protocolos de vitrificação tecidual necessitam ser otimizados para garantir a máxima conservação das características viáveis das células. Portanto, os objetivos do presente trabalho foram caracterizar histologicamente o sistema tegumentar da região auricular periférica (Etapa 1) e avaliar diferentes crioprotetores na vitrificação em superfície sólida de tecido somático de catetos (Etapa 2). Para tanto, fragmentos auriculares (9,0 mm3) foram recuperados de dezesseis animais oriundos do Centro de Multiplicação de Animais Silvestres (CEMAS/UFERSA). Na primeira etapa, amostras teciduais foram avaliadas quanto à caracterização das camadas, seus componentes e atividade proliferativa. Para a segunda etapa, fragmentos teciduais foram criopreservados por vitrificação em superfície sólida em meio essencial mínimo modificado por Dulbecco suplementado com 10% de soro fetal bovino e diferentes crioprotetores e concentrações [dimetilsulfóxido (DMSO; 3,0 M), etilenoglicol (EG; 3,0 M) e associação DMSO/EG (1,5 M; 1,5 M) na ausência e presença de sacarose (0,25 M)]. Após duas semanas, fragmentos aquecidos e não criopreservados (controle) foram analisados usando técnicas histológicas. Assim, para ambas as etapas, amostras teciduais foram avaliadas usando colorações hematoxilina-eosina e tricômico de Gomori, quantificação de regiões argirofílicas organizadoras nucleolares (AgNORs) e viabilidade pelo ensaio de MTT (brometo de 3-[4,5-dimetil-tiazol-2-il]-2,5-difeniltetrazólio). Ainda, na primeira etapa, fragmentos foram analisados por microscopia eletrônica de transmissão. Assim, na primeira etapa, tamanhos de 104,2 μm e 222,6 μm foram observados para epiderme e derme, com uma proporção volumétrica de 36,6% e 58,7%, respectivamente. Além disso, na epiderme, foram evidenciadas as camadas basal (22,5 μm), intermediárias (53,5 μm) e córnea (28,2 μm), com valores médios de 65,3 de células epidermais, 43,4 melanócitos e 14,8 de halos perinucleares. Já a derme apresentou 127 fibroblastos com 2,5 AgNORs por nucléolo. Adicionalmente, a atividade metabólica foi de 0,243. Na segunda etapa, a combinação de 3,0 M de EG com sacarose foi adequada em manter as características teciduais normais quando comparado com os fragmentos não vitrificados, especialmente para a proporção volumétrica da epiderme (61,2 vs. 58,7) e derme (34,5 vs. 36,6), número de fibroblastos (90,3 vs. 127,0) e razão de AgNOR (0,09 vs. 0,17), respectivamente. Em conclusão, o sistema tegumentar auricular periférico de catetos possuiu algumas variações em relação a outros mamíferos, quanto ao número de camadas e espessura da epiderme, quantidade de células epidermais, melanócitos e parâmetros proliferativos. Além disso, 3,0 M de EG com 0,25 M de sacarose resultaram na melhor composição de crioprotetores na vitrificação de tecido somático de catetos / 2017-03-21

Introduction: Cryopreservation of human sperm is considered a routine practice in assisted reproduction laboratories. Semen samples are mainly cryopreserved as a back-up for procedures, donor sperm, and validation of samples from human immunodeficiency virus-positive patients. Human immunodeficiency virus semen samples generally result in a low yield of purified spermatozoa after decontamination. These samples need to be cryopreserved for later use. Unlike conventional cryopreservation, vitrification does not use harmful cryoprotectants, thereby potentially reducing sperm damage. Vitrification is not yet common practice for sperm cryopreservation in assisted reproduction. The aim of this study was to establish the feasibility of utilising vitrification as an alternative to current conventional cryopreservation of spermatozoa. Methods: Semen samples were collected from human immunodeficiency virus-negative patients seeking diagnostic assistance from the unit. All samples were processed according to the unit’s standard protocol. For Study 1A (n=10) washed samples were divided and cryopreserved using three different cryopreservation media, and two different freezing protocols. In Study 1B (n=15), washed samples were divided and preserved using cryoprotectant-free vitrification in 100 μl, 300 μl and 500 μl volumes. For Study 2 (n=35) washed samples were split and cryopreserved using cryoprotectant-free vitrification (utilizing the volume that resulted in the highest quality spermatozoa in Study 1B) and conventional slow freezing (using the medium and protocol that resulted in superior quality spermatozoa in Study 1A). Post thawing, motility and kinetic parameters (Studies 1 and 2), viability (Study 1), mitochondrial membrane potential (Study 2), and DNA fragmentation (Study 2) of the two groups were compared. vi Results: Study 1A indicated that cryopreserving spermatozoa using Freezing Medium resulted in the highest quality spermatozoa with regards to motility and viability (p<0.05). Comparing the two preservation protocols, no conclusion could be reached on which protocol yielded superior results (p>0.05). The RBL freezing method is shorter, simpler and requires less equipment, and was therefore deemed the preferred method. Study 1B showed that the larger vitrification volumes (300 μl and 500 μl) yielded better spermatozoa in terms of motility and viability (p<0.05). No significant difference was observed with respect to the 300 μl and 500 μl vitrification volume groups. For practical reasons, 300 μl volumes will provide sufficient sperm for any procedure and, the intermediate volume ensures that more than one straw can be preserved. Study 2 found that cryoprotectant-free vitrification resulted in spermatozoa with significantly higher mitochondrial membrane potential and significantly lower apoptosis post thawing (p<0.05). Discussion: Conventional cryopreservation methods may compromise various sperm parameters and final yield. In this study, cryopreservation and cryoprotectant-free vitrification had equivalent outcomes with respect to sperm motility. However, the latter method yielded superior results in terms of ΔΨ and DNA sperm fragmentation. In conclusion, vitrification is an easy, rapid and more affordable technique that requires no special equipment. Using vitrification for purified sperm samples of patients could potentially result in a better post thaw quality for ART procedures. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Obstetrics and Gynaecology / unrestricted