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.

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)

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.

Papel da Proteína Morfogenética Óssea 15 (BMP-15) e Kit Ligand (KL) na regulação da foliculogênese em mamíferos / Role of Bone Morphogenetic Protein 15 (BMP-15) and Kit Ligand (KL) in the regulation of folliculogenesis in mammalian

A foliculogênese é coordenada por diversos fatores de crescimento e hormônios responsáveis por garantir o sucesso do desenvolvimento folicular e oocitário. Para a obtenção de oócitos competentes, é necessária uma perfeita interação entre as células somáticas foliculares e o oócito, sendo esta potencialmente regulada por fatores parácrinos produzidos no ovário. Dentre estes fatores, destacam-se a BMP-15 e o KL, sintetizados pelo oócito e pelas células da granulosa, respectivamente. Este artigo revisa o importante papel da BMP-15 e do KL na foliculogênese, enfocando suas características, sítios de expressão, receptores e vias de sinalização, bem como a interação entre estas duas substâncias(AU)

Folliculogenesis is coordinated by many growth factors and hormones responsible for ensuring the success of follicular and oocyte development. To obtain competent oocytes is necessary to have a perfect interaction between follicular somatic cells and the oocyte, which is potentially regulated by paracrine factors produced in the ovary. Among these factors, we highlight BMP-15 and KL, synthesized by the oocyte and granulosa cells, respectively. This article reviews the important role of BMP-15 and KL in folliculogenesis, focusing on their characteristics, sites of expression, receptors and signaling pathways, as well as the interaction between these two substances(AU)

Papel da Proteína Morfogenética Óssea 15 (BMP-15) e Kit Ligand (KL) na regulação da foliculogênese em mamíferos / Role of Bone Morphogenetic Protein 15 (BMP-15) and Kit Ligand (KL) in the regulation of folliculogenesis in mammalian

A foliculogênese é coordenada por diversos fatores de crescimento e hormônios responsáveis por garantir o sucesso do desenvolvimento folicular e oocitário. Para a obtenção de oócitos competentes, é necessária uma perfeita interação entre as células somáticas foliculares e o oócito, sendo esta potencialmente regulada por fatores parácrinos produzidos no ovário. Dentre estes fatores, destacam-se a BMP-15 e o KL, sintetizados pelo oócito e pelas células da granulosa, respectivamente. Este artigo revisa o importante papel da BMP-15 e do KL na foliculogênese, enfocando suas características, sítios de expressão, receptores e vias de sinalização, bem como a interação entre estas duas substâncias

Folliculogenesis is coordinated by many growth factors and hormones responsible for ensuring the success of follicular and oocyte development. To obtain competent oocytes is necessary to have a perfect interaction between follicular somatic cells and the oocyte, which is potentially regulated by paracrine factors produced in the ovary. Among these factors, we highlight BMP-15 and KL, synthesized by the oocyte and granulosa cells, respectively. This article reviews the important role of BMP-15 and KL in folliculogenesis, focusing on their characteristics, sites of expression, receptors and signaling pathways, as well as the interaction between these two substances

Androstenedione and follicle stimulating hormone involvement in the viability and development of goat preantral follicles in vitro

This study investigated the effects of androstenedione and follicle-stimulating hormone (FSH) on the viability and growth of caprine preantral follicles. Ovarian tissues were cultured for 1 or 7 days in Minimum. Essential Medium (MEM) containing androstenedione (0, 1, 10, 50 or 100 ng/ml). FSH (50 ng/ml), or a combination of these two hormones. Cultured and non-cultured control tissues were processed for histological and fluorescence analysis. In comparison with non-cultured control, a sinfnificant reduction was noted in the percentage of normal follicles in all treatments after 1 and 7 days of culture (except in all treatment with 1 ng/ml of androstenedione for 1 day). As the culture period progressed from 1 to 7 days, treatments with 10 ng/ml of androstenedione + FSH or 50 ng/ml of androstenedione alone maintained the percentage of normal follicles. After 1 day, treatments with 10, 50, or 100 ng/ml of androstenedione + FSH, or with 50 ng/ml of androstenedione alone had more developing follicles than fresh control tissue. When comparing the culture periods, treatments with 1, 10 or 100 ng/ml of androstenedione alone, or FSH alone, or FSH with 1 ng/ml of androstenedione, showed an increase in the percentage of developing follicles. After 1 and 7 days, there were no differences in oocyte and follicular diameter among the treated samples and non-cultured control or MEM+ cultured tissue. Fluorescence analysis demonstrated that only fragments cultured in 50 or 100 ng/ml of androstenedione + FSH had viable preantral follicles similar to those observed in MEM+ alone. In conclusion, androstenedione at 50 or 100 ng/ml, either associated with FSH or at 50 ng/ml alone, plays an important role in the maintenance of caprine preantral follicle viability and activation after only a short in vitro culture period. In addition, after 7 days MEM+ alone was efficient in the maintenance of viability and in follicular activation, showing the importance of basic medium composition.(AU)

Expression of protein and mRNA encoding Insulin Growth Factor-I (IGF-I) in goat ovarian follicles and the influence of IGF-I on in vitro development and survival of caprine preantral follicles

The aim of this study was to investigate the protein and mRNA expression levels of IGF-I and the effects of IGF-I on preantral follicle survival and development, using an in vitro goat ovarian cortical culture system. The ovaries were used for immunohistochemical localization of IGF-I protein or used to demonstrate mRNA expression of IGF-I. For the latter goal, preantral and antral follicles, cumulus-oocyte complex, mural granulosa and theca cells were collected to study mRNA expression. For in vitro studies, ovarian cortex were cultured for 1 and 7 days with MEM supplemented IGF-I (0, 1, 10, 50, 100 or 200 ng/ml). Immunohistochemical results showed strong reactions for IGF-I in oocytes and granulosa cells of all follicular stages, except in granulosa cells of primordial and primary follicles. mRNA expression analysis demonstrated a discrete increase in the production of IGF-I during the transition from primordial to the primary and secondary follicle stages. After 7 days of culture, addition of 50 ng/ml of IGF-I to the medium showed the greatest percentage of normal follicles when compared with other concentrations. Furthermore, the highest percentage of primary follicles was observed after 7 days of culture in MEM+ plus 10 and 50 ng/ml of IGF-I. Culture of ovarian tissue for 7 days in MEM+ plus 50 ng/ml of IGF-I promoted the greatest increase (P < 0.05) in follicular diameter of all of the concentrations tested. In conclusion, IGF-I protein and mRNA were expressed in all follicular categories of goat. Furthermore, IGF-I maintained preantral follicle survival, promoted primordial follicle activation and stimulated the transition from intermediate to primary follicles.(AU)

Androstenedione and follicle stimulating hormone involvement in the viability and development of goat preantral follicles in vitro

This study investigated the effects of androstenedione and follicle-stimulating hormone (FSH) on the viability and growth of caprine preantral follicles. Ovarian tissues were cultured for 1 or 7 days in Minimum. Essential Medium (MEM) containing androstenedione (0, 1, 10, 50 or 100 ng/ml). FSH (50 ng/ml), or a combination of these two hormones. Cultured and non-cultured control tissues were processed for histological and fluorescence analysis. In comparison with non-cultured control, a sinfnificant reduction was noted in the percentage of normal follicles in all treatments after 1 and 7 days of culture (except in all treatment with 1 ng/ml of androstenedione for 1 day). As the culture period progressed from 1 to 7 days, treatments with 10 ng/ml of androstenedione + FSH or 50 ng/ml of androstenedione alone maintained the percentage of normal follicles. After 1 day, treatments with 10, 50, or 100 ng/ml of androstenedione + FSH, or with 50 ng/ml of androstenedione alone had more developing follicles than fresh control tissue. When comparing the culture periods, treatments with 1, 10 or 100 ng/ml of androstenedione alone, or FSH alone, or FSH with 1 ng/ml of androstenedione, showed an increase in the percentage of developing follicles. After 1 and 7 days, there were no differences in oocyte and follicular diameter among the treated samples and non-cultured control or MEM+ cultured tissue. Fluorescence analysis demonstrated that only fragments cultured in 50 or 100 ng/ml of androstenedione + FSH had viable preantral follicles similar to those observed in MEM+ alone. In conclusion, androstenedione at 50 or 100 ng/ml, either associated with FSH or at 50 ng/ml alone, plays an important role in the maintenance of caprine preantral follicle viability and activation after only a short in vitro culture period. In addition, after 7 days MEM+ alone was efficient in the maintenance of viability and in follicular activation, showing the importance of basic medium composition.

Expression of protein and mRNA encoding Insulin Growth Factor-I (IGF-I) in goat ovarian follicles and the influence of IGF-I on in vitro development and survival of caprine preantral follicles

The aim of this study was to investigate the protein and mRNA expression levels of IGF-I and the effects of IGF-I on preantral follicle survival and development, using an in vitro goat ovarian cortical culture system. The ovaries were used for immunohistochemical localization of IGF-I protein or used to demonstrate mRNA expression of IGF-I. For the latter goal, preantral and antral follicles, cumulus-oocyte complex, mural granulosa and theca cells were collected to study mRNA expression. For in vitro studies, ovarian cortex were cultured for 1 and 7 days with MEM supplemented IGF-I (0, 1, 10, 50, 100 or 200 ng/ml). Immunohistochemical results showed strong reactions for IGF-I in oocytes and granulosa cells of all follicular stages, except in granulosa cells of primordial and primary follicles. mRNA expression analysis demonstrated a discrete increase in the production of IGF-I during the transition from primordial to the primary and secondary follicle stages. After 7 days of culture, addition of 50 ng/ml of IGF-I to the medium showed the greatest percentage of normal follicles when compared with other concentrations. Furthermore, the highest percentage of primary follicles was observed after 7 days of culture in MEM+ plus 10 and 50 ng/ml of IGF-I. Culture of ovarian tissue for 7 days in MEM+ plus 50 ng/ml of IGF-I promoted the greatest increase (P < 0.05) in follicular diameter of all of the concentrations tested. In conclusion, IGF-I protein and mRNA were expressed in all follicular categories of goat. Furthermore, IGF-I maintained preantral follicle survival, promoted primordial follicle activation and stimulated the transition from intermediate to primary follicles.

Regulation of ovarian folliculogenesis by Kit Ligand and the c-Kit system in mammals

The system comprised of Kit Ligand (KL) and its receptor c-Kit has proven to play a role in normal female reproduction and fertility in mammals. Gene expression studies have revealed that biological activities of ligands and receptors of the KL/c-Kit system are important in controlling apoptosis and cellular proliferation in reproductive tissues. Collectively, these studies have provided a better understanding of ovarian physiology and female fertility through the establishment of the concept that the KL/c-Kit system regulates the viability of primordial germ cells and follicles, initiation of primordial follicle growth, and further oocyte and follicular development through different signaling proteins. The purpose of this article is to review the importance of the KL/c-Kit system in ovarian follicular development, especially in the preantral phase of folliculogenesis.(AU)

Regulation of ovarian folliculogenesis by Kit Ligand and the c-Kit system in mammals

The system comprised of Kit Ligand (KL) and its receptor c-Kit has proven to play a role in normal female reproduction and fertility in mammals. Gene expression studies have revealed that biological activities of ligands and receptors of the KL/c-Kit system are important in controlling apoptosis and cellular proliferation in reproductive tissues. Collectively, these studies have provided a better understanding of ovarian physiology and female fertility through the establishment of the concept that the KL/c-Kit system regulates the viability of primordial germ cells and follicles, initiation of primordial follicle growth, and further oocyte and follicular development through different signaling proteins. The purpose of this article is to review the importance of the KL/c-Kit system in ovarian follicular development, especially in the preantral phase of folliculogenesis.

Angiogenic factors and ovarian follicle development

Ovarian follicles require an adequate blood supply for oxygen, nutrients and hormones, in addition to eliminating CO2 and other metabolites. Acquisition of an adequate vascular supply is probably a limiting step in the selection and maturation of the dominant follicle. In this way, there is a progressive interest in the study of the growth factors involved in the angiogenic process. In addition, a better understanding about the mechanisms that regulate the expression and action of these factors could be a key point to increase the reproductive performance in females. Therefore, this review aims to summarize current data on the importance of the pro- and anti-angiogenic growth factors which regulate angiogenesis in ovarian follicle development.(AU)

Angiogenic factors and ovarian follicle development

Ovarian follicles require an adequate blood supply for oxygen, nutrients and hormones, in addition to eliminating CO2 and other metabolites. Acquisition of an adequate vascular supply is probably a limiting step in the selection and maturation of the dominant follicle. In this way, there is a progressive interest in the study of the growth factors involved in the angiogenic process. In addition, a better understanding about the mechanisms that regulate the expression and action of these factors could be a key point to increase the reproductive performance in females. Therefore, this review aims to summarize current data on the importance of the pro- and anti-angiogenic growth factors which regulate angiogenesis in ovarian follicle development.

Conservação de folículos pré-antrais bovinos em solução salina 0.9 por cento ou TCM 199 / Preservation of bovine preantral follicles in 0.9 percent saline solution or TCM 199

Investigou-se a eficiência da solução salina 0,9 por cento (SS) e TCM 199 na conservação de folículos pré-antrais (FOPA) bovinos in situ em diferentes temperaturas e tempos de incubação. Cada par ovariano foi dividido em 25 fragmentos. Um fragmento foi escolhido aleatoriamente e fixado imediatamente após a coleta (controle). Os demais foram distribuídos em tubos contendo SS ou TCM 199 a 4, 20 ou 39ºC por 2, 4, 12 ou 24h. A análise histológica mostrou que a conservação a 4ºC em ambas as soluções manteve a porcentagem de FOPA normais similar ao controle. A conservação em SS a 20ºC por 12 ou 24h, TCM 199 a 20ºC por 24h e em ambas as soluções a 39ºC a partir de 2h aumentou (P<0,05) a porcentagem de FOPA degenerados comparada à porcentagem de folículos-controle. Em ambas as soluções, independente do tempo de incubação, a porcentagem de folículos normais, após conservação a 39ºC, foi (P<0,05) menor que a obtida com 4 e 20ºC. FOPA bovinos podem ser conservados eficientemente a 4ºC por até 24h em ambas as soluções, e a 20ºC por 4 e 12h em SS e TCM 199, respectivamente.(AU)

The efficiency of 0.9 percent saline solution (SS) and TCM 199 on the preservation of bovine preantral follicles (PF) in situ at different temperatures and incubation times was investigated. Each ovarian pair was divided into 25 fragments. One fragment was taken randomly and immediately fixed (control). The other fragments were distributed in tubes containing SS or TCM 199 at 4, 20 or 39ºC for 2, 4, 12 or 24h. The histological analysis showed that the storage at 4ºC in both solutions kept the percentage of normal follicles similar to control values. Preservation in SS at 20ºC for 12 or 24h, TCM 199 at 20ºC for 24h and in both solutions at 39ºC from 2 h onward (P<0.05) increased the percentage of degenerated follicles when compared with control. In both solutions, independent of incubation time, the percentage of normal follicles observed at 39ºC was (P<0.05) lower them those observed at 4 and 20ºC. Bovine PF can be preserved efficiently at 4ºC for up to 24h in both solutions, at 20ºC for 4 and 12h in SS and TCM 199, respectively.(AU)