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Registro Completo |
Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
Data corrente: |
01/08/1992 |
Data da última atualização: |
05/01/2024 |
Autoria: |
BAIRD, D. T.; MCNEILLY, A. S. |
Título: |
Gonadotrophic control of follicular development and function during the oestrous cycle of the ewe. |
Ano de publicação: |
1981 |
Fonte/Imprenta: |
Journal Reproduction and Fertility. Supplement, v. 30, p. 119-133, 1981. |
Idioma: |
Inglês |
Conteúdo: |
Abstract: In the adult non-pregnant ewe the secretion of FSH is sufficient to ensure a continuous growth and development of antral follicles to 3-5 mm size at all times. Further development and increased secretion of oestradiol through the final 72 h to ovulation depends on adequate stimulation by LH. During anoestrus and the luteal phase of the cycle LH pulses occur too infrequently to stimulate sufficient oestradiol to evoke an LH surge. Moreover, during the luteal phase progesterone secreted by the corpus luteum not only reduces the frequency of LH pulses but also inhibits the ability of oestrogen to evoke an LH surge. At the time of luteal regression the frequency of LH pulses increases to at least one per hour due to the fall in progesterone secretion. This change in pulse frequency of LH is associated with a decrease in the secretion of FSH, probably because of a direct inhibitory action of oestrogen on the anterior pituitary gland. The dominant follicle is probably relatively independent of circulating levels of FSH due to the high concentration of oestradiol and FSH within the microenvironment of the follicular cavity. Once the oestrogen secretion achieves a certain level a preovulatory surge of LH (and FSH) occurs. Increased sensitivity of the anterior pituitary to LH-RH and increased secretion of LH-RH from the hypothalamus both play a part in producing the LH surge. The rise in prolactin at this time probably reflects a decrease in hypothalamic dopamine turnover which is necessary for maximum release of LH-RH. The preovulatory LH surge initially stimulates and then totally inhibits further secretion of oestrogen and androgen from the ovulatory follicle. This suppression of steroid secretion is accompanied by a second peak of FSH at about the time of ovulation. The function of this second peak of FSH remains unknown although it may be responsible for the development of the large antral follicles which occur on Days 3 and 4. It is probably more important in those mammals like the rat and hamster which only form a functional corpus luteum if pregnancy occurs and in which oestrogen is necessary for implantation. MenosAbstract: In the adult non-pregnant ewe the secretion of FSH is sufficient to ensure a continuous growth and development of antral follicles to 3-5 mm size at all times. Further development and increased secretion of oestradiol through the final 72 h to ovulation depends on adequate stimulation by LH. During anoestrus and the luteal phase of the cycle LH pulses occur too infrequently to stimulate sufficient oestradiol to evoke an LH surge. Moreover, during the luteal phase progesterone secreted by the corpus luteum not only reduces the frequency of LH pulses but also inhibits the ability of oestrogen to evoke an LH surge. At the time of luteal regression the frequency of LH pulses increases to at least one per hour due to the fall in progesterone secretion. This change in pulse frequency of LH is associated with a decrease in the secretion of FSH, probably because of a direct inhibitory action of oestrogen on the anterior pituitary gland. The dominant follicle is probably relatively independent of circulating levels of FSH due to the high concentration of oestradiol and FSH within the microenvironment of the follicular cavity. Once the oestrogen secretion achieves a certain level a preovulatory surge of LH (and FSH) occurs. Increased sensitivity of the anterior pituitary to LH-RH and increased secretion of LH-RH from the hypothalamus both play a part in producing the LH surge. The rise in prolactin at this time probably reflects a decrease in hypothalamic dopamine turnover w... Mostrar Tudo |
Thesagro: |
Ciclo Estral; Endocrinologia; Estradiol; Ovino; Reprodução. |
Thesaurus Nal: |
Corpus luteum; Corpus luteum hormones; Endocrine system physiology; Luteinizing hormone; Ovarian follicles; Ovulation; Pituitary gland; Pituitary gonadotropins; Pregnancy; Progesterone; Prolactin; Sheep. |
Categoria do assunto: |
L Ciência Animal e Produtos de Origem Animal |
Marc: |
LEADER 03102naa a2200337 a 4500 001 1520133 005 2024-01-05 008 1981 bl uuuu u00u1 u #d 100 1 $aBAIRD, D. T. 245 $aGonadotrophic control of follicular development and function during the oestrous cycle of the ewe. 260 $c1981 520 $aAbstract: In the adult non-pregnant ewe the secretion of FSH is sufficient to ensure a continuous growth and development of antral follicles to 3-5 mm size at all times. Further development and increased secretion of oestradiol through the final 72 h to ovulation depends on adequate stimulation by LH. During anoestrus and the luteal phase of the cycle LH pulses occur too infrequently to stimulate sufficient oestradiol to evoke an LH surge. Moreover, during the luteal phase progesterone secreted by the corpus luteum not only reduces the frequency of LH pulses but also inhibits the ability of oestrogen to evoke an LH surge. At the time of luteal regression the frequency of LH pulses increases to at least one per hour due to the fall in progesterone secretion. This change in pulse frequency of LH is associated with a decrease in the secretion of FSH, probably because of a direct inhibitory action of oestrogen on the anterior pituitary gland. The dominant follicle is probably relatively independent of circulating levels of FSH due to the high concentration of oestradiol and FSH within the microenvironment of the follicular cavity. Once the oestrogen secretion achieves a certain level a preovulatory surge of LH (and FSH) occurs. Increased sensitivity of the anterior pituitary to LH-RH and increased secretion of LH-RH from the hypothalamus both play a part in producing the LH surge. The rise in prolactin at this time probably reflects a decrease in hypothalamic dopamine turnover which is necessary for maximum release of LH-RH. The preovulatory LH surge initially stimulates and then totally inhibits further secretion of oestrogen and androgen from the ovulatory follicle. This suppression of steroid secretion is accompanied by a second peak of FSH at about the time of ovulation. The function of this second peak of FSH remains unknown although it may be responsible for the development of the large antral follicles which occur on Days 3 and 4. It is probably more important in those mammals like the rat and hamster which only form a functional corpus luteum if pregnancy occurs and in which oestrogen is necessary for implantation. 650 $aCorpus luteum 650 $aCorpus luteum hormones 650 $aEndocrine system physiology 650 $aLuteinizing hormone 650 $aOvarian follicles 650 $aOvulation 650 $aPituitary gland 650 $aPituitary gonadotropins 650 $aPregnancy 650 $aProgesterone 650 $aProlactin 650 $aSheep 650 $aCiclo Estral 650 $aEndocrinologia 650 $aEstradiol 650 $aOvino 650 $aReprodução 700 1 $aMCNEILLY, A. S. 773 $tJournal Reproduction and Fertility. Supplement$gv. 30, p. 119-133, 1981.
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Embrapa Caprinos e Ovinos (CNPC) |
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Registro Completo
Biblioteca(s): |
Embrapa Agricultura Digital. |
Data corrente: |
02/03/2004 |
Data da última atualização: |
28/02/2024 |
Autoria: |
SOUZA, M. I. F.; DISPATO, I. |
Afiliação: |
MARCIA IZABEL FUGISAWA SOUZA, CNPTIA; IVANILDE DISPATO, CNPTIA. |
Título: |
Política editorial da Embrapa Informática Agropecuária: uma proposta. |
Ano de publicação: |
2003 |
Fonte/Imprenta: |
Campinas: Embrapa Informática Agropecuária, 2003. |
Páginas: |
24 p. |
Série: |
(Embrapa Informática Agropecuária. Documentos, 29). |
ISSN: |
1677-9274 |
Idioma: |
Português |
Conteúdo: |
O que é política editorial. objetivos. Princípios e diretrizes. Público e veículos. Política editorial da unidade-proposição. Missão. Objetivos. Projetos prioritários em p e d. Infra-estrutura computacional para transferência de informação. Modelagem e simulação. Público-alvo. Escopo e áreas temáticas.Linha editorial. Veículos. Autorias. Processo editorial. Divulgação da produção científica. |
Palavras-Chave: |
Linha editorial; Política editorial; Publicações. |
Categoria do assunto: |
-- |
URL: |
https://ainfo.cnptia.embrapa.br/digital/bitstream/CNPTIA/10054/1/doc29.pdf
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Marc: |
LEADER 01012nam a2200193 a 4500 001 1008173 005 2024-02-28 008 2003 bl uuuu u0uu1 u #d 022 $a1677-9274 100 1 $aSOUZA, M. I. F. 245 $aPolítica editorial da Embrapa Informática Agropecuária$buma proposta.$h[electronic resource] 260 $aCampinas: Embrapa Informática Agropecuária$c2003 300 $a24 p. 490 $a(Embrapa Informática Agropecuária. Documentos, 29). 520 $aO que é política editorial. objetivos. Princípios e diretrizes. Público e veículos. Política editorial da unidade-proposição. Missão. Objetivos. Projetos prioritários em p e d. Infra-estrutura computacional para transferência de informação. Modelagem e simulação. Público-alvo. Escopo e áreas temáticas.Linha editorial. Veículos. Autorias. Processo editorial. Divulgação da produção científica. 653 $aLinha editorial 653 $aPolítica editorial 653 $aPublicações 700 1 $aDISPATO, I.
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