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1.
Rev. bras. reprod. anim ; 46(4): 364-368, out.-dez. 2022.
Artigo em Português | VETINDEX | ID: biblio-1415066

Resumo

Algunas especies de animales como equinos, pequeños rumiantes, algunos roedores y caninos y felinos silvestres presentan un período de reposo sexual estacional de duración e intensidad variable. Esta estacionalidad está directamente relacionada con las horas luz diarias (fotoperiodo) a las que se hallan sometidos los animales y se evidencia en las localizaciones geográficas en las que existen marcadas variaciones en la duración del día durante el año. En el felino doméstico (Felis silvestris catus) la estacionalidad ovulatoria y estral de la hembra se halla bien documentada y ocurre durante los días que presentan más de 12 horas de luz (primavera-verano). Sin embargo, la estacionalidad reproductiva del gato ha sido definida más tardíamente. Es así que se ha observado que, si bien los gatos producen espermatozoides todo el año, la producción espermática es mayor en la estación reproductiva acompañando la estacionalidad de la hembra. Estos hallazgos han permitido utilizar estos conocimientos para el control de la reproducción y aplicación de biotecnología en felinos domésticos. Asimismo, los conocimientos obtenidos pueden ser aplicados a felinos silvestres tomando al gato doméstico como modelo.(AU)


Algumas espécies de animais como equinos, pequenos ruminantes, alguns roedores e os caninos e felinos selvagens apresentam um período de repouso sexual sazonal de duração e intensidade variáveis. Essa sazonalidade está diretamente relacionada às horas diárias de luz (fotoperíodo) a que os animais são submetidos e é evidenciada em localizações geográficas onde ocorrem variações marcantes na duração do dia durante o ano. No felino doméstico (Felis silvestris catus) a sazonalidade ovulatória e estral da fêmea é bem documentada e ocorre em dias com mais de 12 horas de luz (primavera-verão). No entanto, a sazonalidade reprodutiva do gato foi definida posteriormente, quando foi observado que, embora os gatos produzam espermatozoides ao longo do ano, a produção de espermatozoides é maior na estação reprodutiva, acompanhando a sazonalidade da fêmea. A utilização desses conhecimentos possibilitaram o controle da reprodução e aplicação da biotecnologia em felinos domésticos. Da mesma forma, tomando o gato doméstico como modelo, os conhecimentos obtidos podem ser aplicados aos gatos selvagens.(AU)


Assuntos
Animais , Feminino , Gatos/fisiologia , Ciclo Estral/fisiologia , Fenômenos Reprodutivos Fisiológicos , Fase Folicular/fisiologia , Estações do Ano , Fotoperíodo
2.
Acta sci. vet. (Impr.) ; 50: Pub. 1876, 2022. ilus, tab
Artigo em Português | VETINDEX | ID: biblio-1400770

Resumo

Background: Fixed Time Artificial Insemination (FTAI) has achieved a significant evolution in the last 18 years, however, despite the progress achieved by modern FTAI programs, the conception rates obtained are still low. Therefore, this study aimed to evaluate the interrelation between progesterone levels in the periovulatory period and reproductive parameters of Nellore cows submitted to an FTAI protocol. Materials, Methods & Results: On a random day, called day 0 (D0), 57 cows received a P4 device associated with the intramuscular (IM) application of 2.0 mg of estradiol benzoate. On D9, the P4 devices were removed and then were administered 500 µg of cloprostenol sodium IM; 0.6 mg of estradiol cypionate IM and 300 IUI of Equine Chorionic Gonadotrophin IM. Blood samples were collected for the determination of serum P4 concentrations on D9 and D11 of the protocol. The evaluations of follicular diameter (DFOL), follicular wall area (AFOL) and the vascularization area of the follicle wall (VFOL) were carried out on D11 using B-mode ultrasonography examination and colour Doppler, and then the artificial inseminations were performed. The evaluation of the corpus luteum diameter (CLD), of the total corpus luteum area (CLA), of the area of corpus luteum vascularization (CLV) and blood sampling for determination of postovulatory P4 levels (Post-P4) were performed on D24. For the analysis of the P4 concentration the chemiluminescence method was used, with a sensitivity of 0.1 ng/mL. According to the P4 concentrations on D11, cows were divided into 2 groups, LOW LEVELS OF P4 and HIGH LEVELS OF P4. The diagnosis of pregnancy was performed using transrectal ultrasonography on D45, at this point the cows were divided into 2 groups, PREGNANT and NON-PREGNANT. The correlation between DFOL and P4 dosage on D11 was moderate, negative and significant and between the AFOL and the serum P4 levels on D9, was moderate, negative and significant. As for the other correlations between follicular and luteal parameters and serum P4 levels, these were low to moderate, negative and not significant. Cows in the LOW LEVELS OF P4 group had significantly larger diameter and follicular areas than the cows in the HIGH LEVELS OF P4 group, the other follicular and luteal parameters showed no statistical difference. Of the total 57 cows that were inseminated, 30 cows became pregnant. Cows in the PREGNANT group had serum P4 levels on D9 equivalent to that obtained by the NON-PREGNANT group. However, at D11 the cows that became pregnant presented significantly lower serum P4 levels than cows that did not become pregnant. Discussion: The results of the interrelation between follicular parameters and P4 levels obtained in the present study, pointed out that the lower the levels of P4, the higher the follicular parameters, corroborating with other authors. Thus, larger preovulatory follicles provided high ovulation rates. Periovulatory serum P4 levels did not significantly affect the morphofunctional parameters of the CL. Such findings may be justified by high periovulatory P4 levels resulting from less efficient luteolysis, exert a negative effect on the results of FTAI protocols, because progesterone inhibits the release of LH pulses. It is concluded that lower periovulatory P4 levels established a favourable condition for follicular development and fertility, however, morphofunctional parameters of the corpus luteum were not affected.


Assuntos
Animais , Feminino , Gravidez , Bovinos , Progesterona/análise , Monitorização Uterina/veterinária , Fase Folicular/fisiologia , Folículo Ovariano/crescimento & desenvolvimento , Inseminação Artificial/veterinária , Hemodinâmica
3.
R. bras. Ci. Vet. ; 21(2): 117-121, abr.-jun. 2014. tab, graf
Artigo em Português | VETINDEX | ID: vti-26820

Resumo

Avaliou-se a sincronização folicular e vascularização na parede do folículo dominante (FD) após o tratamento com Cipionato (CE) ou Benzoato de estradiol (BE). No Experimento 1, 45 novilhas receberam implante de P4 (1,0g) e foram distribuídas em 3 grupos de acordo com éster de estradiol administrado pela via intramuscular: 1mL salina; 0,5mg CE ou 2,0mg BE. O diâmetro do FD e a emergência folicular (EF) foram monitorados por 5 dias. No experimento 2, D0 (dia 0): 30 novilhas receberam implante de P4 e 2,0mg BE; D8, retirada do implante e 0,5mg de prostaglandina (cloprostenol); D9: tratamentos: 1mL salina; 0,5mg CE ou 1,0mg BE. O diâmetro e a vascularização do FD foram monitorados do D8 ao D10. Os dados foram analisados por ANOVA ou Kruskal-Wallis, e as médias comparadas por Tukey (5%). No experimento 1, a EF ocorreu mais tarde (P 0,0013) no grupo BE (4,3±0,8 vs. 3,5±0,8d). No experimento 2, o fluxo sanguíneo do FD aumentou (P 0,001) 24h após o tratamento com BE. A taxa de ovulação foi semelhante (P>0,05) entre os grupos (80,0, 70,0 e 55,5%, BE, CE e salina). Conclui-se que nas concentrações utilizadas, o BE, no início do protocolo, retardou a EF e, no final do protocolo, promoveu uma melhor sincronia do FD demonstrada pela elevação do fluxo sanguíneo.(AU)


The study aimed to evaluate synchronization and blood flow of the dominant follicle (DF) after estradiol cypionate (EC) or benzoate(EB) treatment. In experiment 1, progesterone (P4) implants (1.0g) were inserted in 45 heifers, which were given 1mL saline,0.5mg EC or 2.0mg EB. The diameter of the DF and follicle emergence (FE) were recorded for 5 days. For experiment 2, 30 heiferswere given: D0 (day 0): P4 implant and 2.0mg EB; D8: implant removal and 0.5mg of prostaglandin (cloprostenol). On D9, theywere assigned in 1mL saline, 0.5mg EC or 1.0mg EB. From D8 to D10, the diameter and blood flow of the DF was monitored.Data were analyzed by ANOVA or Kruskal-Wallis test, and compared by Tukey (5%). In experiment 1, the FE occurred later(P<0.0013) in EB group (4.3±0.8 vs. 3.5±0.8d). In experiment 2, blood flow of the DF increased (P<0.001) 24h after EB treatment.The ovulation rate was similar (P>0.05) between groups (80.0, 70.0 and 55.5%, EB, EC and saline). The interpretation was that,in these concentrations, the EB, at the beginning, delayed FE and, at the end of the protocol, promoted a better synchrony of theDF, confirmed by the increase of the blood flow.(AU)


Assuntos
Animais , Feminino , Bovinos , Estradiol , Reprodução/fisiologia , Fase Folicular/fisiologia , Ovulação , Ultrassonografia Doppler em Cores
4.
Rev. bras. ciênc. vet ; 21(2): 117-121, abr.-jun. 2014. tab, graf
Artigo em Português | LILACS, VETINDEX | ID: biblio-1491564

Resumo

Avaliou-se a sincronização folicular e vascularização na parede do folículo dominante (FD) após o tratamento com Cipionato (CE) ou Benzoato de estradiol (BE). No Experimento 1, 45 novilhas receberam implante de P4 (1,0g) e foram distribuídas em 3 grupos de acordo com éster de estradiol administrado pela via intramuscular: 1mL salina; 0,5mg CE ou 2,0mg BE. O diâmetro do FD e a emergência folicular (EF) foram monitorados por 5 dias. No experimento 2, D0 (dia 0): 30 novilhas receberam implante de P4 e 2,0mg BE; D8, retirada do implante e 0,5mg de prostaglandina (cloprostenol); D9: tratamentos: 1mL salina; 0,5mg CE ou 1,0mg BE. O diâmetro e a vascularização do FD foram monitorados do D8 ao D10. Os dados foram analisados por ANOVA ou Kruskal-Wallis, e as médias comparadas por Tukey (5%). No experimento 1, a EF ocorreu mais tarde (P 0,0013) no grupo BE (4,3±0,8 vs. 3,5±0,8d). No experimento 2, o fluxo sanguíneo do FD aumentou (P 0,001) 24h após o tratamento com BE. A taxa de ovulação foi semelhante (P>0,05) entre os grupos (80,0, 70,0 e 55,5%, BE, CE e salina). Conclui-se que nas concentrações utilizadas, o BE, no início do protocolo, retardou a EF e, no final do protocolo, promoveu uma melhor sincronia do FD demonstrada pela elevação do fluxo sanguíneo.


The study aimed to evaluate synchronization and blood flow of the dominant follicle (DF) after estradiol cypionate (EC) or benzoate(EB) treatment. In experiment 1, progesterone (P4) implants (1.0g) were inserted in 45 heifers, which were given 1mL saline,0.5mg EC or 2.0mg EB. The diameter of the DF and follicle emergence (FE) were recorded for 5 days. For experiment 2, 30 heiferswere given: D0 (day 0): P4 implant and 2.0mg EB; D8: implant removal and 0.5mg of prostaglandin (cloprostenol). On D9, theywere assigned in 1mL saline, 0.5mg EC or 1.0mg EB. From D8 to D10, the diameter and blood flow of the DF was monitored.Data were analyzed by ANOVA or Kruskal-Wallis test, and compared by Tukey (5%). In experiment 1, the FE occurred later(P0.05) between groups (80.0, 70.0 and 55.5%, EB, EC and saline). The interpretation was that,in these concentrations, the EB, at the beginning, delayed FE and, at the end of the protocol, promoted a better synchrony of theDF, confirmed by the increase of the blood flow.


Assuntos
Feminino , Animais , Bovinos , Estradiol , Fase Folicular/fisiologia , Ovulação , Reprodução/fisiologia , Ultrassonografia Doppler em Cores
5.
Anim. Reprod. (Online) ; 10(4): 662-669, 2013. ilus, graf
Artigo em Inglês | VETINDEX | ID: biblio-1461085

Resumo

Ovarian blood supply is directly related to follicle developmental potential and to oocyte quality, and color Doppler ultrasonography might be a valuable tool to predict in vitro fertilization outcomes. In most studies in large domestic animals, however, the evaluation of follicle blood flow is qualitative (presence or absence of color signal) or dependent on the analysis of a single image. The objective of the present study was to first describe the use of a three-dimensional (3D) modeling of color Doppler images for a quantitative assessment of vascularization in bovine ovarian follicles. Follicular wave emergence was synchronized in Holstein and Gir heifers (n = 20), and follicular dynamics were assessed every 12 h using a color Doppler ultrasound device. The recorded cine-loop of the dominant follicle was decomposed into frames and medical image processing software was used to isolate the Doppler signal, generate the 3D model and calculate the volume of vascularization. In experiment 1, the model was validated by comparing the expected and calculated volumes and was used to predict possible variations in the results of the 2D approach. In experiment 2, vascularization was analyzed during follicular development. In both breeds, the volume of vascularization increased after follicle deviation and was positively correlated (P < 0.05) to follicular diameter (r = 0.65 and 0.54 for Holstein and Gir heifers, respectively). Spatial analysis of the three-dimensional model showed an uneven distribution of vascularization in the follicular wall, with a more intense blood flow being detected in the basal (nearest the ovarian hilus) and lateral regions of the dominant follicles. These results demonstrate the potential of this technique as a new tool for in vivo studies of ovarian physiology in large animals.


Assuntos
Animais , Fase Folicular/fisiologia , Ovário/anatomia & histologia , Bovinos/classificação , Ecocardiografia Doppler
6.
Anim. Reprod. ; 10(4): 662-669, 2013. ilus, graf
Artigo em Inglês | VETINDEX | ID: vti-9891

Resumo

Ovarian blood supply is directly related to follicle developmental potential and to oocyte quality, and color Doppler ultrasonography might be a valuable tool to predict in vitro fertilization outcomes. In most studies in large domestic animals, however, the evaluation of follicle blood flow is qualitative (presence or absence of color signal) or dependent on the analysis of a single image. The objective of the present study was to first describe the use of a three-dimensional (3D) modeling of color Doppler images for a quantitative assessment of vascularization in bovine ovarian follicles. Follicular wave emergence was synchronized in Holstein and Gir heifers (n = 20), and follicular dynamics were assessed every 12 h using a color Doppler ultrasound device. The recorded cine-loop of the dominant follicle was decomposed into frames and medical image processing software was used to isolate the Doppler signal, generate the 3D model and calculate the volume of vascularization. In experiment 1, the model was validated by comparing the expected and calculated volumes and was used to predict possible variations in the results of the 2D approach. In experiment 2, vascularization was analyzed during follicular development. In both breeds, the volume of vascularization increased after follicle deviation and was positively correlated (P < 0.05) to follicular diameter (r = 0.65 and 0.54 for Holstein and Gir heifers, respectively). Spatial analysis of the three-dimensional model showed an uneven distribution of vascularization in the follicular wall, with a more intense blood flow being detected in the basal (nearest the ovarian hilus) and lateral regions of the dominant follicles. These results demonstrate the potential of this technique as a new tool for in vivo studies of ovarian physiology in large animals.(AU)


Assuntos
Animais , Fase Folicular/fisiologia , Ovário/anatomia & histologia , Ecocardiografia Doppler , Bovinos/classificação
7.
Acta sci. vet. (Impr.) ; 38(4): 385-390, 2010.
Artigo em Português | VETINDEX | ID: biblio-1456819

Resumo

Artificial insemination is an established and viable technique to accelerate the genetic advancement and economic return of the cattle. However, compromises the efficiency of detection of estrus results in low insemination rates. To avoid these problems in beef herd, synchronization protocols have been developed that allow inseminate large number of animals within a set period of time. These treatments are known as protocols for synchronization of ovulation for fixed-time artificial insemination (FTAI). There are several slow-release progesterone or progestins devices on the market for use in synchronization of estrus/ovulation programs in cattle, but these devices have a high cost, which results in less use of these protocols by farmers . This study aimed to determine the follicular dynamic of a low cost protocol to synchronize ovulation, which uses vaginal sponges impregnated with medroxy-progesterone acetate (MPA; group 1) and compare it with two trade protocols (groups 2 and 3).


Assuntos
Animais , Bovinos/classificação , Fase Folicular/fisiologia , Ovulação/fisiologia , Estradiol/análise , Progesterona/análise
8.
Acta sci. vet. (Online) ; 38(4): 385-390, 2010.
Artigo em Português | VETINDEX | ID: vti-5114

Resumo

Artificial insemination is an established and viable technique to accelerate the genetic advancement and economic return of the cattle. However, compromises the efficiency of detection of estrus results in low insemination rates. To avoid these problems in beef herd, synchronization protocols have been developed that allow inseminate large number of animals within a set period of time. These treatments are known as protocols for synchronization of ovulation for fixed-time artificial insemination (FTAI). There are several slow-release progesterone or progestins devices on the market for use in synchronization of estrus/ovulation programs in cattle, but these devices have a high cost, which results in less use of these protocols by farmers . This study aimed to determine the follicular dynamic of a low cost protocol to synchronize ovulation, which uses vaginal sponges impregnated with medroxy-progesterone acetate (MPA; group 1) and compare it with two trade protocols (groups 2 and 3).(AU)


Assuntos
Animais , Fase Folicular/fisiologia , Bovinos/classificação , Ovulação/fisiologia , Progesterona/análise , Estradiol/análise
9.
Anim. Reprod. (Online) ; 6(1): 144-158, January/March 2009. ilus, graf
Artigo em Inglês | VETINDEX | ID: biblio-1461577

Resumo

During the recent years, mares have been shown as relevant follicle-related research comparative model for women because of similarities in the number and nature of ovarian follicular waves, a constant relative diameter of the largest follicle between the two species at definable events throughout the ovulatory wave, and similar ultrasonographic characteristics and changes of the preovulatory follicle. In the mare, as in other monovular species (cattle, women), usually only one dominant follicle develops as a result of the deviation mechanism. However, occasionally two or more dominant follicles may also occur. Few studies in mares have addressed the relationships between periovulatory circulating hormone concentrations and single versus multiple dominant/preovulatory follicles. Temporal and mechanistic studies performed recently (years 2005 to 2008) have contributed to elucidation of intriguing relationships among the dominant follicle and circulating hormones and will be the focus of this review. The main topics discussed herein are: (i) development of one versus two dominant follicles with a single ovulation; (ii) development of one versus multiple ovulatory follicles; (iii) conversion of two dominant follicles to double ovulations; (iv) role of hormones in development of double ovulations; (v) interrelationships of periovulatory reproductive hormones; (vi) repeatability of preovulatory follicle diameter and hormones; and (vii) factors that affect preovulatory follicle diameter and hormones, such as breeds and types of mares, season, body condition, and aging.


Assuntos
Feminino , Animais , Cavalos/fisiologia , Folículo Ovariano/crescimento & desenvolvimento , Hormônios Esteroides Gonadais/fisiologia , Fase Folicular/fisiologia
10.
Anim. Reprod. ; 6(1): 144-158, January/March 2009. ilus, graf
Artigo em Inglês | VETINDEX | ID: vti-5974

Resumo

During the recent years, mares have been shown as relevant follicle-related research comparative model for women because of similarities in the number and nature of ovarian follicular waves, a constant relative diameter of the largest follicle between the two species at definable events throughout the ovulatory wave, and similar ultrasonographic characteristics and changes of the preovulatory follicle. In the mare, as in other monovular species (cattle, women), usually only one dominant follicle develops as a result of the deviation mechanism. However, occasionally two or more dominant follicles may also occur. Few studies in mares have addressed the relationships between periovulatory circulating hormone concentrations and single versus multiple dominant/preovulatory follicles. Temporal and mechanistic studies performed recently (years 2005 to 2008) have contributed to elucidation of intriguing relationships among the dominant follicle and circulating hormones and will be the focus of this review. The main topics discussed herein are: (i) development of one versus two dominant follicles with a single ovulation; (ii) development of one versus multiple ovulatory follicles; (iii) conversion of two dominant follicles to double ovulations; (iv) role of hormones in development of double ovulations; (v) interrelationships of periovulatory reproductive hormones; (vi) repeatability of preovulatory follicle diameter and hormones; and (vii) factors that affect preovulatory follicle diameter and hormones, such as breeds and types of mares, season, body condition, and aging.(AU)


Assuntos
Animais , Feminino , Cavalos/fisiologia , Folículo Ovariano/crescimento & desenvolvimento , Hormônios Esteroides Gonadais/fisiologia , Fase Folicular/fisiologia
11.
Anim. Reprod. (Online) ; 6(1): 159-171, January/March 2009. ilus, graf
Artigo em Inglês | VETINDEX | ID: biblio-1461576

Resumo

Follicle development can be divided into gonadotrophin-independent, gonadotrophin-responsive and gonadotrophin-dependent phases. The basic level of control of folliculogenesis lies with the actions of an extensively observed but poorly understood range of somatic and germ cell derived local factors that constitute an intrafollicular developmental cascade that regulates the proliferative and differentiative phases of follicle development. As follicle development progresses, the follicle become increasingly responsive to the actions of the pituitary gonadotrophins FSH and LH and during these phases of development local factors act to modulate the actions of gonadotrophins so that the fate of each follicle depends on an intrafollicular balance between local factors which augment or attenuate gonadotrophic actions. Gonadotrophins are therefore not a prerequisite for the continued growth of gonadotrophin-responsive pre-antral follicles, but FSH does appear to stimulate development and these actions are modulated by local growth factors, such as IGFs, AMH and BMPs. Naturally occurring mutations in sheep for a number of these factors or there receptors have provided insights into their roles during both the early and terminal stages of follicle development and we have recently produced extensive evidence supporting a major role for members of the BMP system in regulating follicle selection mechanisms through increased activation of gonadotrophic augmentors (BMP-6), decreased activation of attenuators (BMP-15, GDF-9, AMH) or a combination of these two mechanisms resulting in the deregulation of the normal follicle selection mechanisms. The terminal stages of follicle development, however, remain primarily under the control of the pituitary gonadotrophins, with both FSH and LH having essential and inter-related roles in regulating final maturation and selection of the ovulatory follicle and the oocyte which it contains.


Assuntos
Feminino , Animais , Folículo Ovariano/crescimento & desenvolvimento , Gonadotropinas/efeitos adversos , Ovinos/crescimento & desenvolvimento , Fase Folicular/fisiologia , Ovinos/fisiologia
12.
Anim. Reprod. ; 6(1): 159-171, January/March 2009. ilus, graf
Artigo em Inglês | VETINDEX | ID: vti-5973

Resumo

Follicle development can be divided into gonadotrophin-independent, gonadotrophin-responsive and gonadotrophin-dependent phases. The basic level of control of folliculogenesis lies with the actions of an extensively observed but poorly understood range of somatic and germ cell derived local factors that constitute an intrafollicular developmental cascade that regulates the proliferative and differentiative phases of follicle development. As follicle development progresses, the follicle become increasingly responsive to the actions of the pituitary gonadotrophins FSH and LH and during these phases of development local factors act to modulate the actions of gonadotrophins so that the fate of each follicle depends on an intrafollicular balance between local factors which augment or attenuate gonadotrophic actions. Gonadotrophins are therefore not a prerequisite for the continued growth of gonadotrophin-responsive pre-antral follicles, but FSH does appear to stimulate development and these actions are modulated by local growth factors, such as IGFs, AMH and BMPs. Naturally occurring mutations in sheep for a number of these factors or there receptors have provided insights into their roles during both the early and terminal stages of follicle development and we have recently produced extensive evidence supporting a major role for members of the BMP system in regulating follicle selection mechanisms through increased activation of gonadotrophic augmentors (BMP-6), decreased activation of attenuators (BMP-15, GDF-9, AMH) or a combination of these two mechanisms resulting in the deregulation of the normal follicle selection mechanisms. The terminal stages of follicle development, however, remain primarily under the control of the pituitary gonadotrophins, with both FSH and LH having essential and inter-related roles in regulating final maturation and selection of the ovulatory follicle and the oocyte which it contains.(AU)


Assuntos
Animais , Feminino , Ovinos/crescimento & desenvolvimento , Folículo Ovariano/crescimento & desenvolvimento , Gonadotropinas/efeitos adversos , Ovinos/fisiologia , Fase Folicular/fisiologia
13.
Anim. Reprod. (Online) ; 6(1): 114-124, January/March 2009.
Artigo em Inglês | VETINDEX | ID: biblio-1461580

Resumo

Although the discovery that follicles in bovine ovaries grow in a wave-like fashion has presented challenges for estrus synchronization and superovulation, recent protocols, designed to control follicular function have permitted fixed-time AI or fixed-time embryo transfer with high pregnancy rates, and the initiation of superstimulatory treatments at a self-appointed time, all without the necessity of estrus detection. The key is the synchronization of follicle wave emergence. More recent studies have revealed that it is not only possible to synchronize the timing of ovulation for fixed-time AI in single ovulating animals, but also in superstimulated donors. Ultrasound-guided follicle ablation is very efficacious in synchronizing follicle wave emergence but is difficult to apply in the field. Similarly, the induction of ovulation with GnRH or LH will effectively synchronize follicle wave emergence, but ovulation occurs in only 60 to 70% of cases. The administration of estradiol benzoate in progestin-treated cattle effectively synchronizes follicle wave emergence for both superovulation and estrus synchronization, but estradiol benzoate is not available in many countries. The challenge now is to use knowledge of follicle wave dynamics to design alternatives.


Assuntos
Feminino , Animais , Bovinos , Folículo Ovariano/crescimento & desenvolvimento , Inseminação Artificial/métodos , Sincronização do Estro/métodos , Testes de Função Ovariana/métodos , Fase Folicular/fisiologia , Superovulação , Técnicas Reprodutivas/veterinária
14.
Anim. Reprod. ; 6(1): 114-124, January/March 2009.
Artigo em Inglês | VETINDEX | ID: vti-5977

Resumo

Although the discovery that follicles in bovine ovaries grow in a wave-like fashion has presented challenges for estrus synchronization and superovulation, recent protocols, designed to control follicular function have permitted fixed-time AI or fixed-time embryo transfer with high pregnancy rates, and the initiation of superstimulatory treatments at a self-appointed time, all without the necessity of estrus detection. The key is the synchronization of follicle wave emergence. More recent studies have revealed that it is not only possible to synchronize the timing of ovulation for fixed-time AI in single ovulating animals, but also in superstimulated donors. Ultrasound-guided follicle ablation is very efficacious in synchronizing follicle wave emergence but is difficult to apply in the field. Similarly, the induction of ovulation with GnRH or LH will effectively synchronize follicle wave emergence, but ovulation occurs in only 60 to 70% of cases. The administration of estradiol benzoate in progestin-treated cattle effectively synchronizes follicle wave emergence for both superovulation and estrus synchronization, but estradiol benzoate is not available in many countries. The challenge now is to use knowledge of follicle wave dynamics to design alternatives.(AU)


Assuntos
Animais , Feminino , Bovinos , Inseminação Artificial/métodos , Folículo Ovariano/crescimento & desenvolvimento , Testes de Função Ovariana/métodos , Sincronização do Estro/métodos , Fase Folicular/fisiologia , Técnicas Reprodutivas/veterinária , Superovulação
15.
Braz. j. vet. res. anim. sci ; 44(2): 103-114, 2007. graf
Artigo em Português | VETINDEX | ID: vti-5419

Resumo

Além do controle neuroendócrino do eixo hipotalâmico-hipofisáriogonadal existem fatores autócrinos e parácrinos que controlam o crescimento, seleção e ovulação nos mamíferos. Estes fatores ainda não estão bem estabelecidos. Objetivando analisar as variações nas concentrações plasmáticas da endotelina-1 em um ciclo estral bovino e seus efeitos sobre o cultivo de células da granulosa, foram analisadas amostras plasmáticas de 5 dias (0, 1, 3, 7 e 13) de um ciclo estral, tendo como base o dia da ovulação (dia 0) e 3 horas (8, 13 e 16) do 14º dia do ciclo. As variações nas concentrações plasmáticas de endotelina-1 não foram significativas para os dias assim como para as horas do dia analisado. Células da granulosa obtidas de folículos antrais foram cultivadas durante 48 horas com diferentes concentrações de endotelina. Os resultados demonstraram que a endotelina atua de maneira dosedependente estimulando a produção de progesterona e inibindo o crescimento celular.(AU)


Besides the neuroendocrine control of the hypotalamic-hypophisarygonodal axis there are autocrines and paracrines factors that control the growth, selection and ovulation in the mammals. These factors are not well established yet. Aiming to analyze the variations in the endotelin-1plasmatic concentrations in a bovine estral cycle and their effects on the culture of granulosa cells, plasma samples of 5 days (0,1,3,7 and 13) from an estral cycle have been analyzed, having as basis the ovulation day (day 0) and 3 hours (8,13,16) of the fourteenth day of the cycle. The variations in the endothelin-1 concentrations were not significant for the days as well as for the hours of the analyzed day. Granulosa cells obtained from antral follicles were cultivated during 24 hours with different concentrations of endothelin. The results demonstrated that the endothelin-1 acts in a dose-dependent manner stimulating the production of progesterone and inhibiting the cellular growth.(AU)


Assuntos
Animais , Endotelina-1/efeitos adversos , Esteroides/efeitos adversos , Esteroides/análise , Células da Granulosa , Fase Folicular/fisiologia , Ciclo Estral/sangue , Bovinos
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