Impacto do estresse térmico na maturação oocitária in vitro em bovinos: uma revisão / Impact of heat stress on oocyte in vitro maturation in bovine: a review

O estresse térmico, que ocorre nos meses mais quentes do ano, é a principal causa da redução dafertilidade em mamíferos nesse período. Pode ser ocasionado por respostas indiretas com efeitos sistêmicos, bemcomo por respostas locais nas células ovarianas. Estudos têm demonstrado uma sensibilidade dos oócitosbovinos crescidos in vivo ao estresse térmico, culminando com efeitos negativos na maturação tanto in vivoquanto in vitro. Os efeitos negativos mais observados são: aumento nas taxas de apoptose e de espécies reativasde oxigênio, alterações na produção hormonal e redução nas taxas de oócitos que alcançam o estágio de metáfaseII in vitro. A presente revisão tem como propósito abordar os principais aspectos relacionados ao impacto doestresse térmico em oócitos bovinos.(AU)

During the summer period, heat stress is the main cause of infertility in mammals. Heat stress can becaused by indirect responses with systemic effects, as well as local responses in ovarian cells. Studies haveshown a sensitivity of oocytes grown in vivo to heat stress, culminating with negative effects on in vivo and invitro maturation. The most common negative effects of heat stress are: increasing the apoptotic rate and reactiveoxygen species production, altering the hormone production, and reducing the number of oocytes that reachmetaphase II stage in vitro. This review addressed some important aspects related to the impact of heat stress incattle oocytes.(AU)

Impacto do estresse térmico na maturação oocitária in vitro em bovinos: uma revisão / Impact of heat stress on oocyte in vitro maturation in bovine: a review

O estresse térmico, que ocorre nos meses mais quentes do ano, é a principal causa da redução dafertilidade em mamíferos nesse período. Pode ser ocasionado por respostas indiretas com efeitos sistêmicos, bemcomo por respostas locais nas células ovarianas. Estudos têm demonstrado uma sensibilidade dos oócitosbovinos crescidos in vivo ao estresse térmico, culminando com efeitos negativos na maturação tanto in vivoquanto in vitro. Os efeitos negativos mais observados são: aumento nas taxas de apoptose e de espécies reativasde oxigênio, alterações na produção hormonal e redução nas taxas de oócitos que alcançam o estágio de metáfaseII in vitro. A presente revisão tem como propósito abordar os principais aspectos relacionados ao impacto doestresse térmico em oócitos bovinos.

During the summer period, heat stress is the main cause of infertility in mammals. Heat stress can becaused by indirect responses with systemic effects, as well as local responses in ovarian cells. Studies haveshown a sensitivity of oocytes grown in vivo to heat stress, culminating with negative effects on in vivo and invitro maturation. The most common negative effects of heat stress are: increasing the apoptotic rate and reactiveoxygen species production, altering the hormone production, and reducing the number of oocytes that reachmetaphase II stage in vitro. This review addressed some important aspects related to the impact of heat stress incattle oocytes.

Effects of a-MEM and TCM-199 culture media and epidermal growth factor on survival and growth of goat and sheep preantral follicles cultured in vitro

The aim of this study was to evaluate the effect of culture media (Alpha Minimum Essential Medium, α-MEM; and Tissue Culture Medium-199, TCM-199) in the absence or presence of Epidermal Growth Factor (EGF) on an in vitro culture of goat and sheep preantral follicles enclosed in ovarian tissue. The fragments of ovarian cortex from both species were immediately analyzed after collection (non-cultured control group) or cultured for 1 or 7 days in α-MEM+ or TCM-199+in the absence or presence of EGF (10 ng/ml). Before and after the culture, the fragments of ovarian cortex were analyzed by classical histology and fluorescence microscopy. After 1 day of culture, all treatments decreased the percentage of morphologically normal follicles when compared to non-cultured control in both species (P 0.05). Regarding follicle activation, an increase in the percentage of growing follicles was observed in all treatments after 7 days of culture when compared to the control group in both species. However, in sheep, after 7 days, only the treatments α-MEM+/EGF and TCM-199+showed larger(P < 0.05) oocytes than the control group. In conclusion, the TCM-199+ Preserved goat preantral follicle viability after in vitro culture. Furthermore, the media α-MEM+/EGF and TCM-199+ increased the oocyte diameter after 7 days of culture in sheep. Therefore, it isrecommended to use TCM-199+ In the culture of preantral follicles in both species.

Effects of a-MEM and TCM-199 culture media and epidermal growth factor on survival and growth of goat and sheep preantral follicles cultured in vitro

The aim of this study was to evaluate the effect of culture media (Alpha Minimum Essential Medium, α-MEM; and Tissue Culture Medium-199, TCM-199) in the absence or presence of Epidermal Growth Factor (EGF) on an in vitro culture of goat and sheep preantral follicles enclosed in ovarian tissue. The fragments of ovarian cortex from both species were immediately analyzed after collection (non-cultured control group) or cultured for 1 or 7 days in α-MEM+ or TCM-199+in the absence or presence of EGF (10 ng/ml). Before and after the culture, the fragments of ovarian cortex were analyzed by classical histology and fluorescence microscopy. After 1 day of culture, all treatments decreased the percentage of morphologically normal follicles when compared to non-cultured control in both species (P < 0.05). In fluorescence microscopy, viable sheep follicles were observed to decrease in all treatments after 7 days of culture when compared to non-cultured controls. However, in goats, the culture with TCM-199+maintained follicle viability after 7 days of culture, similar to fresh tissue (P > 0.05). Regarding follicle activation, an increase in the percentage of growing follicles was observed in all treatments after 7 days of culture when compared to the control group in both species. However, in sheep, after 7 days, only the treatments α-MEM+/EGF and TCM-199+showed larger(P < 0.05) oocytes than the control group. In conclusion, the TCM-199+ Preserved goat preantral follicle viability after in vitro culture. Furthermore, the media α-MEM+/EGF and TCM-199+ increased the oocyte diameter after 7 days of culture in sheep. Therefore, it isrecommended to use TCM-199+ In the culture of preantral follicles in both species.(AU)

Participação da esfingosina 1-fosfato e do fator inibidor da leucemia no cultivo in vitro de folículos ovarianos pré-antrais de cabras / The role of Sphingosine 1-phosphate and Leukemia Inhibitory Factor in the culture of goats preantral follicles in vitro

A manipulação de oócitos inclusos em folículos ovarianos pré-antrais (MOIFOPA) possibilita oaumento do potencial reprodutivo das fêmeas a partir do isolamento e cultivo de folículos pré-antrais (FOPA).Fisiologicamente, vários fatores de crescimento estão envolvidos durante o processo da foliculogênese, muitosdos quais até o momento não foram testados em cabras. Esta revisão tem como objetivo correlacionar aparticipação da S1P e do LIF no cultivo dos FOPA e, assim, possibilitar uma melhor compreensão dosmecanismos relacionados com a foliculogênese.(AU)

The manipulation of oocytes included in preantral Follicles increasing the reproductive potential of thefemales from the isolation and culture of preantral follicles was studied. Physiologically various growth factorsare involved in the folliculogenesis process, many of which have not been tested in goats so far. This review aimsto correlate the involvement of S1P and LIF in the culture of preantral follicle enabling a better understandingof the mechanisms related to folliculogenesis.(AU)

Participação da esfingosina 1-fosfato e do fator inibidor da leucemia no cultivo in vitro de folículos ovarianos pré-antrais de cabras / The role of Sphingosine 1-phosphate and Leukemia Inhibitory Factor in the culture of goats preantral follicles in vitro

A manipulação de oócitos inclusos em folículos ovarianos pré-antrais (MOIFOPA) possibilita oaumento do potencial reprodutivo das fêmeas a partir do isolamento e cultivo de folículos pré-antrais (FOPA).Fisiologicamente, vários fatores de crescimento estão envolvidos durante o processo da foliculogênese, muitosdos quais até o momento não foram testados em cabras. Esta revisão tem como objetivo correlacionar aparticipação da S1P e do LIF no cultivo dos FOPA e, assim, possibilitar uma melhor compreensão dosmecanismos relacionados com a foliculogênese.

The manipulation of oocytes included in preantral Follicles increasing the reproductive potential of thefemales from the isolation and culture of preantral follicles was studied. Physiologically various growth factorsare involved in the folliculogenesis process, many of which have not been tested in goats so far. This review aimsto correlate the involvement of S1P and LIF in the culture of preantral follicle enabling a better understandingof the mechanisms related to folliculogenesis.

Steady-state levels of vasoactive intestinal peptide (VIP) mRNA in goat ovaries and the effect of VIP on the in vitro development of isolated preantral follicles

The aims of this study were to verify the steady-state level of vasoactive intestinal peptide (VIP) mRNA in goat follicles at various developmental stages and to investigate the influence of VIP on the survival, antrum formation and growth of secondary follicles cultured for 6 days. Primordial, primary and secondary goat follicles and small and large antral follicles were obtained to quantify VIP mRNA by real-time reverse transcription with the polymerase chain reaction. The influence of VIP and the presence or absence of follicle-stimulating hormone (FSH) on the development of secondary follicles and on mRNA expression for VIP and FSH receptor (FSHR) were determined after 6 days of culture. Survival, antrum formation and follicular diameter were evaluated every other day of culture. The levels of VIP mRNA in primary and secondary follicles were significantly higher than in primordial follicles. Cumulus–oocyte complexes (COCs) from both small and large antral follicles had significantly higher levels ofVIP mRNA than their respective granulosa/theca cells. During culture, the addition of VIP and/or FSH had o effect on follicular development. However, the presence of FSH and/or VIP in the culture medium significantly reduced VIP mRNA levels, but did not alter FSHR mRNA levels. In conclusion, VIP mRNA was detected in all goat follicular categories and cellular types, VIP and/or FSH did not affect the development of secondary follicles and reduce the expression of VIP mRNA levels.(AU)

Steady-state levels of vasoactive intestinal peptide (VIP) mRNA in goat ovaries and the effect of VIP on the in vitro development of isolated preantral follicles

The aims of this study were to verify the steady-state level of vasoactive intestinal peptide (VIP) mRNA in goat follicles at various developmental stages and to investigate the influence of VIP on the survival, antrum formation and growth of secondary follicles cultured for 6 days. Primordial, primary and secondary goat follicles and small and large antral follicles were obtained to quantify VIP mRNA by real-time reverse transcription with the polymerase chain reaction. The influence of VIP and the presence or absence of follicle-stimulating hormone (FSH) on the development of secondary follicles and on mRNA expression for VIP and FSH receptor (FSHR) were determined after 6 days of culture. Survival, antrum formation and follicular diameter were evaluated every other day of culture. The levels of VIP mRNA in primary and secondary follicles were significantly higher than in primordial follicles. Cumulus–oocyte complexes (COCs) from both small and large antral follicles had significantly higher levels ofVIP mRNA than their respective granulosa/theca cells. During culture, the addition of VIP and/or FSH had o effect on follicular development. However, the presence of FSH and/or VIP in the culture medium significantly reduced VIP mRNA levels, but did not alter FSHR mRNA levels. In conclusion, VIP mRNA was detected in all goat follicular categories and cellular types, VIP and/or FSH did not affect the development of secondary follicles and reduce the expression of VIP mRNA levels.

Sphingosine 1-phosphate promotes activation of aprine preantral follicle in vitro / Esfingosina 1-fosfato promove ativação de folículos pré-antrais de caprinos in vitro

This study describes the effect of sphingosine 1-phosphate (S1P) for development of preantral follicle, therefore the activation and follicular viability of caprine follicles cultured in vitro. Ovarian fragments were cultured for 1 or 7 days in Minimum Essential Medium with different S1P concentrations (0, 1, 10, 50, 100 or 200ng/mL). All ovarian fragments were processed for histological analysis in optical microscopy, transmission electron microscopy and fluorescence analysis. The treatment using 1ng/mL of S1P was able to maintain the percentage of normal follicles with the progression of the culture from day 1 to 7. At end of the 7-day culture period there was a significant reduction (P<0.05) in the percentage of primordial follicles in all groups treated with S1P, compared with fresh control (FC) and Control Culture (CC), which was followed by an increase of activated follicles (intermediary, primary and secondary). In addition, the culture for 7 days with media supplemented with S1P with 1ng/mL preserved the ultrastructure of organelles and kept the preantral follicular viability when evaluated by fluorescence microscopy. In conclusion, after 7 days of culture, the 1ng/mL of S1P activates the development of preantral caprine follicles, cultured in situ and maintains the oocitary and follicular viability.(AU)

Este estudo descreve o efeito da esfingosina 1-fosfato (S1P) no desenvolvimento de folículos pré-antrais, portanto da ativação e viabilidade de folículos caprinos cultivados in vitro. Fragmentos de ovários foram cultivados por um ou sete dias em meio essencial mínimo com diferentes concentrações de S1P (0, 1, 10, 50, 100 ou 200ng/mL). Os fragmentos de ovário foram processados para análise histológica em microscopia óptica, microscopia eletrônica e microscopia de fluorescência. O tratamento usando 1ng/mL de S1P foi capaz de manter a porcentagem de folículos normais durante o período de cultivo de sete dias. Ao final do período de cultivo, houve uma redução significativa (p<0,05) na porcentagem de folículos primordiais em todos os grupos tratados com S1P, comparados com os grupos controle (FC e CC), seguida por um aumento do número de folículos ativados (intermediários, primários e secundários). Adicionalmente, na cultura por sete dias com meio suplementado com S1P (1ng/mL), houve preservação da ultraestrutura das organelas e manteve-se a viabilidade dos folículos pré-antrais avaliados por microscopia de fluorescência. Em conclusão, após sete dias de cultura, o meio suplementado com 1ng/mL de S1P ativa o desenvolvimento de folículos pré-antrais de caprino, cultivados in situ e mantém as viabilidades oocitária e folicular.(AU)

Transforming growth factor-β (TGF-β) maintains follicular ultrastructure and stimulates preantral follicle growth in caprine ovarian tissue cultured in vitro / Fator de crescimento transformante-β (TGF-β) mantém a ultraestrutura folicular e estimula o crescimento de folículos pré-antrais caprinos inclusos em tecido ovariano cultivado in vitro

The objectives of this study were to investigate whether TGF-β affect the survival, activation and further growth of goat primordial follicles enclosed in ovarian cortex after in vitro culture. Goat ovaries were collected from an abattoir and pieces of ovarian tissues were cultured for one or seven days in a supplemented alpha Minimum Essential Medium, alone or containing TGF-β (1, 5, 10 or 50ng/mL). Ovarian tissues from the fresh control as well as those cultured were processed for histological and ultrastructural studies. The results showed that when compared with fresh control, there was decrease in the percentages of histologically normal follicles in all treatments only after seven days culture. TGF-β did not affect the activation of preantral follicles regardless of its concentration, however, larger follicles diameter (P<0.05) was observed using 10ng/mL TGF-β than in the fresh control and other treatments. Moreover, this concentration maintained the normal ultrastructure after seven days of culture. In conclusion, TGF-β showed additional effect on the follicle growth and the maintenance of ultrastructural integrity of goat preantral follicles enclosed in ovarian tissue when used at 10ng/mL during seven days of culture.(AU)

O objetivo desse estudo foi investigar se o TGF-β afeta a sobrevivência, ativação e crescimento de folículos primordiais caprinos inclusos no córtex ovariano após o cultivo in vitro. Ovários de cabras foram coletados em abatedouro e fragmentos de tecido ovariano foram cultivados por um e sete dias em meio essencial mínimo alfa (α-MEM+) sozinho ou suplementado com TGF-β (1, 5, 10 ou 50ng/mL). Fragmentos ovarianos não cultivados e cultivados foram processados para análise histológica e ultraestrutural. Os resultados mostraram que, comparado ao controle fresco, houve diminuição no percentual de folículos morfologicamente normais em todos os tratamentos somente após sete dias de cultivo. O TGF-β não afetou a ativação folicular independente da concentração testada, contudo, o diâmetro folicular foi superior (P<0.05) no tratamento com 10ng/mL de TGF-β quando comparado ao controle fresco e aos demais tratamentos. Além disso, essa mesma concentração manteve a ultraestrutura normal dos folículos após sete dias de cultivo. Em conclusão, o TGF-β apresentou efeito adicional no crescimento folicular e na manutenção da integridade ultraestrutural de folículos pré-antrais caprinos inclusos no tecido ovariano quando utilizado na concentração de 10ng/mL durante sete dias de cultivo.(AU)

Equine preantral follicle harvesting, processing, and in vitro culture: the journey has already started

Preantral follicles are of great abundance in mammalian ovaries and the vast majority (>99.9%) never become ovulatory; therefore, the ability to rescue these otherwise wasted follicles seems very aooealing. Considering there are striking similarities in antral follicle dynamics between mares and women, the mare might become a good model to study early (preantral and antral) folliculogenesis in women, with several advantages related to using an animal model. Studies in our laboratory recently validated the use of a transvaginal ultrasound-guided ovarian. Biopsy Pick-Up (BPU) method to harvest preantral follicles using the mare as a model to study early folliculogenesis (Haag et al., 2013a, b, c). This article will review some of the important findings of our recent studies related to the harvesting, processing, and culture of equine preantral follicles and discuss those with the limited information availeble in the literature.

Equine preantral follicle harvesting, processing, and in vitro culture: the journey has already started

Preantral follicles are of great abundance in mammalian ovaries and the vast majority (>99.9%) never become ovulatory; therefore, the ability to rescue these otherwise wasted follicles seems very aooealing. Considering there are striking similarities in antral follicle dynamics between mares and women, the mare might become a good model to study early (preantral and antral) folliculogenesis in women, with several advantages related to using an animal model. Studies in our laboratory recently validated the use of a transvaginal ultrasound-guided ovarian. Biopsy Pick-Up (BPU) method to harvest preantral follicles using the mare as a model to study early folliculogenesis (Haag et al., 2013a, b, c). This article will review some of the important findings of our recent studies related to the harvesting, processing, and culture of equine preantral follicles and discuss those with the limited information availeble in the literature.(AU)

Hormônio do crescimento (GH) e fator de crescimento semelhante à insulina-I (IGF-I): importantes reguladores das foliculogêneses in vivo e in vitro / Growth Hormone (GH) and Insulin-like growth factor I (IGF-I): major regulators of folliculogenesis in vivo and in vitro

A foliculogênese é caracterizada pelo desenvolvimento folicular, envolvendo as etapas de ativação, crescimento e maturação. Durante este evento, hormônios e fatores de crescimento agem em conjunto controlando os complexos mecanismos envolvidos na fisiologia reprodutiva. Dentre estes, destacam-se o hormônio do crescimento (GH) e o fator de crescimento semelhante à insulina I (IGF-I), que estão presentes nas diversas etapas da foliculogênese, atuando de forma direta e/ou indireta a fim de proporcionar o desenvolvimento folicular. Durante as últimas décadas, pesquisas acerca do efeito destas substâncias, isoladas ou em associação, têm sido amplamente realizadas. Neste sentido, esta revisão irá abordar o papel do GH e do IGF-I na regulação da foliculogênese, bem como a interação destes fatores nos desenvolvimentos foliculares in vivo e in vitro.(AU)

The folliculogenesis is characterized by follicular development, involving the steps of activation, growth and maturation. During this event, hormones and growth factors act jointly managing the complex mechanisms involved in reproductive physiology. Among these, we highlight the Growth Hormone (GH) and Insulin-like Growth Factor I (IGF-I) that are present at different stages of folliculogenesis, acting in ways direct or indirect to provide follicular development. During recent decades, searches on the effect of these substances alone or in combination have been widely performed. Therefore, this review will address the role of GH and IGF-I in regulation of folliculogenesis, as well as the interaction of these factors in follicular development in vivo and in vitro.(AU)

Fator de crescimento epidermal como mediador de sobrevivência e desenvolvimento folicular / Epidermal growth factor as mediator of survival and follicular development

Diversos fatores intraovarianos atuam no ovário dos mamíferos regulando o desenvolvimento folicular. Entre eles, destaca-se o fator de crescimento epidermal (EGF), considerado um potente fator mitogênico para células foliculares e luteais. Tendo em vista a importância deste fator no âmbito do desenvolvimento folicular, a presente revisão de literatura tem como objetivo descrever as principais implicações do EGF na foliculogênese, destacando seu padrão de expressão no ovário, suas principais vias de sinalização celular, bem como seu efeito como fator de sobrevivência e de desenvolvimento folicular.(AU)

Several intra-ovarian factors act regulating the mammalian follicular development in the ovary. Among them highlights the epidermal growth factor (EGF), considered a potent mitogenic factor for follicular and luteal cells. Given the importance of this factor within the follicular development, this review describes the main implications of EGF in the folliculogenesis, focusing on its expression pattern in the ovary, the major pathways of cell signaling and its effect as a survival and follicular development factor.(AU)

Hormônio do crescimento (GH) e fator de crescimento semelhante à insulina-I (IGF-I): importantes reguladores das foliculogêneses in vivo e in vitro / Growth Hormone (GH) and Insulin-like growth factor I (IGF-I): major regulators of folliculogenesis in vivo and in vitro

A foliculogênese é caracterizada pelo desenvolvimento folicular, envolvendo as etapas de ativação, crescimento e maturação. Durante este evento, hormônios e fatores de crescimento agem em conjunto controlando os complexos mecanismos envolvidos na fisiologia reprodutiva. Dentre estes, destacam-se o hormônio do crescimento (GH) e o fator de crescimento semelhante à insulina I (IGF-I), que estão presentes nas diversas etapas da foliculogênese, atuando de forma direta e/ou indireta a fim de proporcionar o desenvolvimento folicular. Durante as últimas décadas, pesquisas acerca do efeito destas substâncias, isoladas ou em associação, têm sido amplamente realizadas. Neste sentido, esta revisão irá abordar o papel do GH e do IGF-I na regulação da foliculogênese, bem como a interação destes fatores nos desenvolvimentos foliculares in vivo e in vitro.

The folliculogenesis is characterized by follicular development, involving the steps of activation, growth and maturation. During this event, hormones and growth factors act jointly managing the complex mechanisms involved in reproductive physiology. Among these, we highlight the Growth Hormone (GH) and Insulin-like Growth Factor I (IGF-I) that are present at different stages of folliculogenesis, acting in ways direct or indirect to provide follicular development. During recent decades, searches on the effect of these substances alone or in combination have been widely performed. Therefore, this review will address the role of GH and IGF-I in regulation of folliculogenesis, as well as the interaction of these factors in follicular development in vivo and in vitro.

Fator de crescimento epidermal como mediador de sobrevivência e desenvolvimento folicular / Epidermal growth factor as mediator of survival and follicular development

Diversos fatores intraovarianos atuam no ovário dos mamíferos regulando o desenvolvimento folicular. Entre eles, destaca-se o fator de crescimento epidermal (EGF), considerado um potente fator mitogênico para células foliculares e luteais. Tendo em vista a importância deste fator no âmbito do desenvolvimento folicular, a presente revisão de literatura tem como objetivo descrever as principais implicações do EGF na foliculogênese, destacando seu padrão de expressão no ovário, suas principais vias de sinalização celular, bem como seu efeito como fator de sobrevivência e de desenvolvimento folicular.

Several intra-ovarian factors act regulating the mammalian follicular development in the ovary. Among them highlights the epidermal growth factor (EGF), considered a potent mitogenic factor for follicular and luteal cells. Given the importance of this factor within the follicular development, this review describes the main implications of EGF in the folliculogenesis, focusing on its expression pattern in the ovary, the major pathways of cell signaling and its effect as a survival and follicular development factor.

FSH and LH enhance the development of goat preantral follicles cultured in vitro

This study evaluated th e effect of increased follicle stimulating hormone (FSH) concentrations on the expression of mRNA for LH receptors after in vitro culture of goat preantral follicles ( ≥ 150 μm) for 18 days. It also investigated whether the addition of luteinizing hormone (LH) to the culture medium, which contained increasing concentrations of FSH throughout the culture period, influenced the surv ival, growth and antrum formation of in vitro cultured goat preantral follicles. In experiment 1, preantral follicles were cultured in α -MEM + or α -MEM + supplemented with increasing concentrations of FSH throughout the culture period (sequential medium: FSH 100 ng/ml (days 0 to 6), FSH 500 ng/ml (days 6 to 12) and FSH 1000 ng/ml (days 12 to 18). The expression of luteinizing hormone receptor (LHR) was analyzed in noncultured and cultured follicles using real time RT-PCR. In experiment 2, isolated preantral follicles were cultured for 18 days in a sequential medium containing FSH (control) or a control medium supplemented with LH (50 or 100 ng/ml) from day 12 of culture onwards. Follicle development was evaluated on the basis of antr al cavity formation as well as follicular and oocyte growth after in vitro maturation. FSH stimulated a significant increase in the expression of mRNA for LH receptors after 18 days of culture. Furthermore, after 18 days, all tested media promoted follicular survival and antrum formation; however, a significant increase in the rate of follicular growth and resumption of meiosis was ob served when LH was used compared to the control. In conclusion, preantral follicles cultured in a medium supplemented with FSH increased LH receptor mR NA levels. Moreover, the addition of LH to the culture medium containing increasing concentrations of FSH (sequential medium) improved the in vitro development of goat preantral follicles.

FSH and LH enhance the development of goat preantral follicles cultured in vitro

This study evaluated th e effect of increased follicle stimulating hormone (FSH) concentrations on the expression of mRNA for LH receptors after in vitro culture of goat preantral follicles ( ≥ 150 μm) for 18 days. It also investigated whether the addition of luteinizing hormone (LH) to the culture medium, which contained increasing concentrations of FSH throughout the culture period, influenced the surv ival, growth and antrum formation of in vitro cultured goat preantral follicles. In experiment 1, preantral follicles were cultured in α -MEM + or α -MEM + supplemented with increasing concentrations of FSH throughout the culture period (sequential medium: FSH 100 ng/ml (days 0 to 6), FSH 500 ng/ml (days 6 to 12) and FSH 1000 ng/ml (days 12 to 18). The expression of luteinizing hormone receptor (LHR) was analyzed in noncultured and cultured follicles using real time RT-PCR. In experiment 2, isolated preantral follicles were cultured for 18 days in a sequential medium containing FSH (control) or a control medium supplemented with LH (50 or 100 ng/ml) from day 12 of culture onwards. Follicle development was evaluated on the basis of antr al cavity formation as well as follicular and oocyte growth after in vitro maturation. FSH stimulated a significant increase in the expression of mRNA for LH receptors after 18 days of culture. Furthermore, after 18 days, all tested media promoted follicular survival and antrum formation; however, a significant increase in the rate of follicular growth and resumption of meiosis was ob served when LH was used compared to the control. In conclusion, preantral follicles cultured in a medium supplemented with FSH increased LH receptor mR NA levels. Moreover, the addition of LH to the culture medium containing increasing concentrations of FSH (sequential medium) improved the in vitro development of goat preantral follicles.(AU)

Influência dos hormônios esteroides na foliculogênese / Influence of steroid hormones on folliculogenesis

Os hormônios esteroides estão diretamente relacionados com o processo de foliculogênese, o qual é bastante complexo e influenciado também por vários fatores de crescimento e por hormônios. Diversos estudos demonstraram a importância dos esteroides no desenvolvimento folicular, na maturação oocitária, bem como na formação do corpo lúteo. Desta forma, o objetivo da presente revisão foi sintetizar o processo de formação e o mecanismo de ação dos hormônios esteroides na foliculogênese, com ênfase no estradiol, na progesterona e nos andrógenos.(AU)

Steroid hormones are directly related to the folliculogenesis process, which is very complex and also influenced by several growth factors and hormones. Several studies have demonstrated the importance of steroids in follicular development in mature oocytes as well as corpus luteum formation. The objective of this review is to address the process of synthesis and mechanism of action of steroid hormones in folliculogenesis, with emphasis on estradiol, progesterone and androgens.(AU)

Influência dos hormônios esteroides na foliculogênese / Influence of steroid hormones on folliculogenesis

Os hormônios esteroides estão diretamente relacionados com o processo de foliculogênese, o qual é bastante complexo e influenciado também por vários fatores de crescimento e por hormônios. Diversos estudos demonstraram a importância dos esteroides no desenvolvimento folicular, na maturação oocitária, bem como na formação do corpo lúteo. Desta forma, o objetivo da presente revisão foi sintetizar o processo de formação e o mecanismo de ação dos hormônios esteroides na foliculogênese, com ênfase no estradiol, na progesterona e nos andrógenos.

Steroid hormones are directly related to the folliculogenesis process, which is very complex and also influenced by several growth factors and hormones. Several studies have demonstrated the importance of steroids in follicular development in mature oocytes as well as corpus luteum formation. The objective of this review is to address the process of synthesis and mechanism of action of steroid hormones in folliculogenesis, with emphasis on estradiol, progesterone and androgens.