Maternal contributions to pregnancy success: from gamete quality to uterine environment

The establishment and maintenance of a pregnancy that goes to term is sine qua non for the long-term sustainability of dairy and beef cattle operations. The oocyte plays a critical role in providing the factors necessary for preimplantation embryonic development. Furthermore, the female, or maternal, environment where oocytes and embryos develop is crucial for the establishment and maintenance of a pregnancy to term. During folliculogenesis, the oocyte must sequentially acquire meiotic and developmental competence, which are the results of a series of molecular events preparing the highly specialized gamete to return to totipotency after fertilization. Given that folliculogenesis is a lengthy process in the cow, the occurrence of disease, metabolic imbalances, heat stress, or other adverse events can make it challenging to maintain oocyte quality. Following fertilization, the newly formed embryo must execute a tightly planned program that includes global DNA remodeling, activation of the embryonic genome, and cell fate decisions to form a blastocyst within a few days and cell divisions. The increasing use of assisted reproductive technologies creates an additional layer of complexity to ensure the highest oocyte and embryo quality given that in vitro systems do not faithfully recreate the physiological maternal environment. In this review, we discuss cellular and molecular factors and events known to be crucial for proper oocyte development and maturation, as well as adverse events that may negatively affect the oocyte; and the importance of the uterine environment, including signaling proteins in the maternal-embryonic interactions that ensure proper embryo development. We also discuss the impact of assisted reproductive technologies in oocyte and embryo quality and developmental potential, and considerations when looking into the prospects for developing systems that allow for in vitro gametogenesis as a tool for assisted reproduction in cattle.(AU)

Ovarian development of Xiphopenaeus kroyeri (Crustacea: Penaeidae) from Espírito Santo, southeastern Brazil / Desenvolvimento ovariano de Xiphopenaeus kroyeri (Crustacea: Penaeidae) no Espírito Santo, sudeste do Brasil

This study aimed to describe and characterize the stages of gonadal development of females of Xiphopenaeus kroyeri caught by artisanal fishers in Espírito Santo state, southeastern region of Brazil. All females (n= 1,831) were subjected to macroscopic and microscopic morphological analysis (n= 333) of the ovaries. From the morphology, coloration and degree of turgidity of the fresh ovary, macroscopic analysis determined five stages of gonadal development. The macroscopic analysis showed difficulties in differentiating the immature and spawning stages due to the similarity between the colors of the ovaries, which confirms the need to perform the macroscopic and histological analysis simultaneously for fisheries management studies. Microscopic observations allowed us to analyze the following six stages of cell development: oogonia, previtellogenic oocytes, primary vitellogenic oocytes, secondary vitellogenic oocytes, mature oocytes and atretic oocytes. From this, five stages of gonadal development were defined, i.e., immature, early development, advanced development, mature and spawned. The presence of peripheral bodies was not observed in this species. These results help to clarify and better understand the reproductive and population aspects of the Atlantic Seabob, which are fundamental for the establishment of management and conservation measures of this resource.

Este estudo teve como objetivo descrever e caracterizar os estágios de desenvolvimento gonadal de fêmeas de Xiphopenaeus kroyeri capturado por pescadores artesanais no Estado do Espírito Santo, região sudeste (Região sudeste = Rio de Janeiro, São Paulo, Minas Gerais e Espírito Santo) do Brasil. Todas as fêmeas (n= 1.831) foram submetidas à análise morfológica macroscópica e microscópica (n= 333) dos ovários. A partir da morfologia, coloração e grau de turgidez do ovário fresco, a análise macroscópica determinou cinco estágios de desenvolvimento gonadal. A análise macroscópica mostrou dificuldades em diferenciar os estágios imaturo e reprodutivo devido à semelhança entre as cores dos ovários, o que confirma a necessidade de realizar a análise macroscópica e histológica simultaneamente para estudos de manejo pesqueiro. As observações microscópicas permitiram analisar os seguintes seis estágios de desenvolvimento celular: oogônias, ovócitos prévitelogênicos, ovócitos em vitelogênese primária, ovócitos em vitelogênese secundária, ovócitos maduros e ovócitos atrésicos. A partir disso, foram definidos cinco estágios de desenvolvimento gonadal, ou seja, imaturo, desenvolvimento inicial, desenvolvimento avançado, maduro e desovado. A presença de corpos periféricos não foi observada nesta espécie. Estes resultados ajudam a esclarecer e compreender melhor os aspetos reprodutivos e populacionais do camarão do Atlântico, que são fundamentais para o estabelecimento de medidas de gestão e conservação deste recurso.

Effect of environmental contamination on female and male gametes – A lesson from bovines

Endocrine-disrupting compounds (EDCs) and foodborne contaminants are environmental pollutants that are considered reproductive toxicants due to their deleterious effects on female and male gametes. Among the EDCs, the phthalate plasticizers are of growing concern. In-vivo and in-vitro models indicate that the oocyte is highly sensitive to phthalates. This review summarizes the effects of di(2-ethylhexyl) phthalate and its major metabolite mono(2-ethyhexyl) phthalate (MEHP) on the oocyte. MEHP reduces the proportion of oocytes that fertilize, cleave and develop to the blastocyst stage. This is associated with negative effects on meiotic progression, and disruption of cortical granules, endoplasmic reticulum and mitochondrial reorganization. MEHP alters mitochondrial membrane polarity, increases reactive oxygen species levels and induces alterations in genes associated with oxidative phosphorylation. A carryover effect from the oocyte to the blastocyst is manifested by alterations in the transcriptomic profile of blastocysts developed from MEHP-treated oocytes. Among foodborne contaminants, the pesticide atrazine (ATZ) and the mycotoxin aflatoxin B1 (AFB1) are of high concern. The potential hazards associated with exposure of spermatozoa to these contaminants and their carryover effect to the blastocyst are described. AFB1 and ATZ reduce spermatozoa's viability, as reflected by a high proportion of cells with damaged plasma membrane; induce acrosome reaction, expressed as damage to the acrosomal membrane; and interfere with mitochondrial function, characterized by hyperpolarization of the membrane. ATZ and AFB1-treated spermatozoa show a high proportion of cells with fragmented DNA. Exposure of spermatozoa to AFB1 and ATZ reduces fertilization and cleavage rates, but not that of blastocyst formation. However, fertilization with AFB1- or ATZ-treated spermatozoa impairs transcript expression in the formed blastocysts, implying a carryover effect. Taken together, the review indicates the risk of exposing farm animals to environmental contaminants, and their deleterious effects on female and male gametes and the developing embryo.

Effect of environmental contamination on female and male gametes A lesson from bovines

Endocrine-disrupting compounds (EDCs) and foodborne contaminants are environmental pollutants that are considered reproductive toxicants due to their deleterious effects on female and male gametes. Among the EDCs, the phthalate plasticizers are of growing concern. In-vivo and in-vitro models indicate that the oocyte is highly sensitive to phthalates. This review summarizes the effects of di(2-ethylhexyl) phthalate and its major metabolite mono(2-ethyhexyl) phthalate (MEHP) on the oocyte. MEHP reduces the proportion of oocytes that fertilize, cleave and develop to the blastocyst stage. This is associated with negative effects on meiotic progression, and disruption of cortical granules, endoplasmic reticulum and mitochondrial reorganization. MEHP alters mitochondrial membrane polarity, increases reactive oxygen species levels and induces alterations in genes associated with oxidative phosphorylation. A carryover effect from the oocyte to the blastocyst is manifested by alterations in the transcriptomic profile of blastocysts developed from MEHP-treated oocytes. Among foodborne contaminants, the pesticide atrazine (ATZ) and the mycotoxin aflatoxin B1 (AFB1) are of high concern. The potential hazards associated with exposure of spermatozoa to these contaminants and their carryover effect to the blastocyst are described. AFB1 and ATZ reduce spermatozoa's viability, as reflected by a high proportion of cells with damaged plasma membrane; induce acrosome reaction, expressed as damage to the acrosomal membrane; and interfere with mitochondrial function, characterized by hyperpolarization of the membrane. ATZ and AFB1-treated spermatozoa show a high proportion of cells with fragmented DNA. Exposure of spermatozoa to AFB1 and ATZ reduces fertilization and cleavage rates, but not that of blastocyst formation. However, fertilization with AFB1- or ATZ-treated spermatozoa impairs transcript expression in the formed blastocysts, implying a carryover effect. Taken together, the review indicates the risk of exposing farm animals to environmental contaminants, and their deleterious effects on female and male gametes and the developing embryo.(AU)

Gametogênese de peixes: aspectos relevantes para o manejo reprodutivo / Gametogenesis in Fish:relevant aspects for the reproductive management

Na maioria dos peixes Teleostei, a gametogênese é um evento cíclico e sazonal. A renovação dos gametas, seu desenvolvimento, diferenciação, maturação e liberação provocam várias alterações nas características das gônadas ao longo dos ciclos reprodutivos anuais. Essas alterações são utilizadas para reconhecer fases nos ciclos reprodutivos. O reconhecimento dessas fases constitui um dos parâmetros aplicados na gestão dos recursos pesqueiros. Este trabalho apresenta uma recente proposta de reconhecimento das fases reprodutivas desenvolvida para os Perciformes adaptada para os Ostariophysi neotropicais (Siluriformes e Characiformes). Soma-se a isso uma breve descrição da gametogênese nos peixes Teleostei. (AU)

In most of Teleostei fish gametogenesis is a cyclical and seasonal event. The renewal of the gametes, their development, differentiation, maturation and release provoke many alterations of gonadal features along the annual reproductive cycles. These alterations are used to recognize phases of the reproductive cycles. The recognition of these phases constitutes one of the parameters applied to the management of fisheries resources. Herein a recent proposal of the recognition of the reproductive phases in the Perciformes is exposed and its adaptation to the Neotropical Ostariophysi (Siluriformes and Characiformes) is provided. In addition, the gametogenesis in the Teleostei fish is briefly described.(AU)

Gametogênese de peixes: aspectos relevantes para o manejo reprodutivo / Gametogenesis in Fish:relevant aspects for the reproductive management

Na maioria dos peixes Teleostei, a gametogênese é um evento cíclico e sazonal. A renovação dos gametas, seu desenvolvimento, diferenciação, maturação e liberação provocam várias alterações nas características das gônadas ao longo dos ciclos reprodutivos anuais. Essas alterações são utilizadas para reconhecer fases nos ciclos reprodutivos. O reconhecimento dessas fases constitui um dos parâmetros aplicados na gestão dos recursos pesqueiros. Este trabalho apresenta uma recente proposta de reconhecimento das fases reprodutivas desenvolvida para os Perciformes adaptada para os Ostariophysi neotropicais (Siluriformes e Characiformes). Soma-se a isso uma breve descrição da gametogênese nos peixes Teleostei.

In most of Teleostei fish gametogenesis is a cyclical and seasonal event. The renewal of the gametes, their development, differentiation, maturation and release provoke many alterations of gonadal features along the annual reproductive cycles. These alterations are used to recognize phases of the reproductive cycles. The recognition of these phases constitutes one of the parameters applied to the management of fisheries resources. Herein a recent proposal of the recognition of the reproductive phases in the Perciformes is exposed and its adaptation to the Neotropical Ostariophysi (Siluriformes and Characiformes) is provided. In addition, the gametogenesis in the Teleostei fish is briefly described.

Perfil proteico do líquido folicular coletado de ovários em diferentes fases do ciclo estral de bovinos / Proteic profile of follicular fluid from ovaries in different phases of bovine estrous cycle

O microambiente do gameta feminino é o líquido folicular e, portanto, as proteínas ali presentes devem interferir na qualidade do oócito. Este experimento foi delineado com o objetivo de verificar o perfil proteico do líquido folicular de folículos em diferentes fases do ciclo estral de bovinos. Para tanto, os líquidos foliculares provenientes de ovários de vacas de abatedouro foram alocados em 5 diferentes fases do ciclo estral, levando em conta a presença ou ausência do corpo lúteo (CL) e sua caracterização morfológica. “Pools” de líquido folicular foram coletados de folículos de 2 a 7 mm de ovários em 5 diferentes fases do ciclo estral (1=CL inicial, hemorrágico; 2=CL em desenvolvimento; 3=CL maduro; 4=CL em regressão e 5=ausência de CL). O perfil proteico foi avaliado por eletroforese em gel de poliacrilamida e determinado em porcentagens nas amostras de cada fase. Os polipeptídeos de 35, 32, 30 e 18 KDa variaram consideravelmente nas amostras. O polipeptídeo de mesmo peso molecular que o IGFBP-2 está mais presente nas amostras de líquido folicular ao final do ciclo estral. Maior número de polipeptídeos foi observado em folículos antrais pequenos de ovários em que o CL está em regressão.

The female gamete’s microenvironment is the follicular fluid. The proteins in the follicular fluid must interfere in the oocyte quality. The objective of this study was to verify the protein profile in the follicular fluid of different phases of bovine estrous cycle. The follicular fluid was taken from follicles of bovine ovaries obtained at slaughterhouse. The ovaries were classified into five different phases of estrous cycle, according to presence or absence of corpus luteum (CL) and the morphologic characteristics. Pools of follicular fluid were collected from follicles ranging from 2 to 7mm in diameter from ovaries in five different phases of estrous cycle (1=initial CL, hemorrhagic; 2= developing CL; 3= mature CL; 4=regressing CL and 5=absence CL). The protein profile was evaluated by poliacrilamide eletrophoresis and determined by percentages of samples from each phase. The polypeptides with molecular weigh of 35, 32, 30 and 18 KDa changed considerably in samples from different phases of estrous cycle. The polypeptide with the same molecular weight of IGFBP-2 is more observed in samples from follicular fluid in the end of estrous cycle. The most polypeptides were observed in small follicles from ovaries with regressing CL.

Perfil proteico do líquido folicular coletado de ovários em diferentes fases do ciclo estral de bovinos / Proteic profile of follicular fluid from ovaries in different phases of bovine estrous cycle

O microambiente do gameta feminino é o líquido folicular e, portanto, as proteínas ali presentes devem interferir na qualidade do oócito. Este experimento foi delineado com o objetivo de verificar o perfil proteico do líquido folicular de folículos em diferentes fases do ciclo estral de bovinos. Para tanto, os líquidos foliculares provenientes de ovários de vacas de abatedouro foram alocados em 5 diferentes fases do ciclo estral, levando em conta a presença ou ausência do corpo lúteo (CL) e sua caracterização morfológica. “Pools” de líquido folicular foram coletados de folículos de 2 a 7 mm de ovários em 5 diferentes fases do ciclo estral (1=CL inicial, hemorrágico; 2=CL em desenvolvimento; 3=CL maduro; 4=CL em regressão e 5=ausência de CL). O perfil proteico foi avaliado por eletroforese em gel de poliacrilamida e determinado em porcentagens nas amostras de cada fase. Os polipeptídeos de 35, 32, 30 e 18 KDa variaram consideravelmente nas amostras. O polipeptídeo de mesmo peso molecular que o IGFBP-2 está mais presente nas amostras de líquido folicular ao final do ciclo estral. Maior número de polipeptídeos foi observado em folículos antrais pequenos de ovários em que o CL está em regressão.(AU)

The female gametes microenvironment is the follicular fluid. The proteins in the follicular fluid must interfere in the oocyte quality. The objective of this study was to verify the protein profile in the follicular fluid of different phases of bovine estrous cycle. The follicular fluid was taken from follicles of bovine ovaries obtained at slaughterhouse. The ovaries were classified into five different phases of estrous cycle, according to presence or absence of corpus luteum (CL) and the morphologic characteristics. Pools of follicular fluid were collected from follicles ranging from 2 to 7mm in diameter from ovaries in five different phases of estrous cycle (1=initial CL, hemorrhagic; 2= developing CL; 3= mature CL; 4=regressing CL and 5=absence CL). The protein profile was evaluated by poliacrilamide eletrophoresis and determined by percentages of samples from each phase. The polypeptides with molecular weigh of 35, 32, 30 and 18 KDa changed considerably in samples from different phases of estrous cycle. The polypeptide with the same molecular weight of IGFBP-2 is more observed in samples from follicular fluid in the end of estrous cycle. The most polypeptides were observed in small follicles from ovaries with regressing CL.(AU)

Importância da indução artificial na reprodução de rãs / Importance of artificial induction in reproduction of frogs

O aprimoramento do desenvolvimento das técnicas de indução da reprodução de anfíbios anuros vai permitir um aumento da ranicultura mundial, possibilitando, num futuro próximo, a regularidade na produção de rãs. Os conhecimentos da fisiologia da reprodução de anfíbios anuros propiciaram a determinação de manejo adequado que permite a maturação gonadal das rãs em cativeiro, como também gera aumento nos processos de maturação final dos gametas.(AU)

The improvement of the development of techniques to induce breeding of amphibians will allow an increase in frog culture worldwide, enabling the near future regularity in the production of frogs. The knowledge of reproductive physiology of amphibians allowed the determination of appropriate management that allows the gonad maturation of the frogs in captivity, but also causes an increase in the processes of final maturation of gametes.(AU)

Importância da indução artificial na reprodução de rãs / Importance of artificial induction in reproduction of frogs

O aprimoramento do desenvolvimento das técnicas de indução da reprodução de anfíbios anuros vai permitir um aumento da ranicultura mundial, possibilitando, num futuro próximo, a regularidade na produção de rãs. Os conhecimentos da fisiologia da reprodução de anfíbios anuros propiciaram a determinação de manejo adequado que permite a maturação gonadal das rãs em cativeiro, como também gera aumento nos processos de maturação final dos gametas.

The improvement of the development of techniques to induce breeding of amphibians will allow an increase in frog culture worldwide, enabling the near future regularity in the production of frogs. The knowledge of reproductive physiology of amphibians allowed the determination of appropriate management that allows the gonad maturation of the frogs in captivity, but also causes an increase in the processes of final maturation of gametes.

TESTES DE COLORAÇÃO VITAL PARA ESTIMATIVA DA VIABILIDADE DE OÓCITOS DE TAMBAQUI (Colossoma macropomum) E MATRINXÃ (Brycon amazonicus)

Atualmente não existe uma técnica eficaz para avaliar a qualidade de oócitos na piscicultura de forma prática e acessível. O teste de integridade da membrana celular com o corante vital azul de tripan (AT), geralmente utilizado para identificar células com lise de membrana, mostra-se uma opção para avaliar a qualidade de oócitos, uma vez que a integridade da membrana é descrita como um indicador de qualidade em oócitos. Testes de integridade de membrana com AT foram conduzidos para a previsão da viabilidade de oócitos de Colossoma macropomum e Brycon amazonicus, analisando a correlação dos seus resultados com os parâmetros do sucesso reprodutivo. Os oócitos foram expostos às concentrações de 0,05; 0,04; 0,03; 0,02 e 0,01% de AT durante 1 minuto e em seguida avaliados em estereomicroscópio. A percentagem de oócitos não corados (intactos) de cada amostra foi correlacionada com taxas de fertilização e de eclosão utilizando regressão linear (p > 5%). Observou-se uma fraca correlação entre os resultados dos tratamentos e as taxas de fertilização e eclosão em ambas as espécies, porém os testes permitiram a detecção de oócitos inviáveis. Concluiu-se que os testes de integridade AT não foram eficazes em prever o sucesso de desova em C. macropomum e B. amazonicus.

Nowadays there is no effective technique to evaluate the quality of oocytes in fish farming in a practical and affordable way. The cell membrane integrity test with vital dye trypan blue (TB) could be an option for evaluating the quality of oocytes in fish. Membrane integrity assays with TB were conducted in order to predict the viability of Colossoma macropomum and Brycon amazonicus oocytes. Oocytes were exposed to concentrations of 0.05; 0.04; 0.03; 0.02 and 0.01% TB for 1 minute and subsequently evaluated under stereomicroscope. The percentage of unstained (intact) oocytes from each sample was correlated with fertilization and hatching rates using linear regression (p-value > 0.05). It was observed a weak correlation between the results of the treatments and fertilization and hatching rates in both species, however the tests have enabled the detection of non-viable oocytes. The TB integrity tests were not effective in predicting the success of spawning in C. macropomum and B. amazonicus.

Agentes crioprotetores intracelulares: características e utilização na criopreservação de tecido ovariano e oócitos / Intracellular Cryoprotectant Agents: Characteristics and Use of Ovarian Tissue and Oocyte Cryopreservation

Background: The application of cryopreservation in human and animal reproductive medicine has stimulated several studies about the effects of low temperatures and freezing processes on cells and tissues, in order to develop efficient protocols for gamete and embryo preservation. Moreover, cryopreservation is a fundamental tool for the establishment of animal germplasm banks, allowing the preservation of genetic material from several species and breeds or for further study and/or recovery of desirable characteristics. For the success of cryopreservation, the addition of an intracellular cryoprotectant agent in the freezing solution is indispensable. However, issues related to intracellular cryoprotectant agents used, e.g., their metabolism and potential toxicity, must be examined carefully so we can choose the cryoprotectant most suitable for a specific structure. Review: In this regard, this review introduces several aspects of cryopreservation, such as basic principles and methods used (slow freezing and vitrification), describing the fundamental steps of cryoprotectant agent’s exposure, cooling, storage, thawing or warming and removal of the cryoprotectant agent. The addition of an intracellular cryoprotectant to the freezing solution is essential, but does not guarantee the success of the cryopreservation protocol, due to its toxic effect, which requires a perfect balance between cryoprotectant concentration, temperature and exposure time to the structure which will be cryopreserved. Some studies attribute the toxicity of these agents mainly to the secondary metabolites formed when the cell resumes its activi ty and gradually begins to metabolize the cryoprotectant agent.[...]

Agentes crioprotetores intracelulares: características e utilização na criopreservação de tecido ovariano e oócitos / Intracellular Cryoprotectant Agents: Characteristics and Use of Ovarian Tissue and Oocyte Cryopreservation

Background: The application of cryopreservation in human and animal reproductive medicine has stimulated several studies about the effects of low temperatures and freezing processes on cells and tissues, in order to develop efficient protocols for gamete and embryo preservation. Moreover, cryopreservation is a fundamental tool for the establishment of animal germplasm banks, allowing the preservation of genetic material from several species and breeds or for further study and/or recovery of desirable characteristics. For the success of cryopreservation, the addition of an intracellular cryoprotectant agent in the freezing solution is indispensable. However, issues related to intracellular cryoprotectant agents used, e.g., their metabolism and potential toxicity, must be examined carefully so we can choose the cryoprotectant most suitable for a specific structure. Review: In this regard, this review introduces several aspects of cryopreservation, such as basic principles and methods used (slow freezing and vitrification), describing the fundamental steps of cryoprotectant agents exposure, cooling, storage, thawing or warming and removal of the cryoprotectant agent. The addition of an intracellular cryoprotectant to the freezing solution is essential, but does not guarantee the success of the cryopreservation protocol, due to its toxic effect, which requires a perfect balance between cryoprotectant concentration, temperature and exposure time to the structure which will be cryopreserved. Some studies attribute the toxicity of these agents mainly to the secondary metabolites formed when the cell resumes its activi ty and gradually begins to metabolize the cryoprotectant agent.[...](AU)