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Registro Completo |
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Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
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Data corrente: |
08/11/2000 |
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Data da última atualização: |
22/11/2002 |
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Autoria: |
BARTLEWSKI, P. M.; BEARD, A. P.; COOK, S. J.; RAWLINGS, N. C. |
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Título: |
Ovarian follicular dynamics during anoestrus in ewes. |
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Ano de publicação: |
1998 |
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Fonte/Imprenta: |
Journal of Reproduction and Fertility, v. 113, n. 2, p. 275-285, 1998. |
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Idioma: |
Inglês |
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Conteúdo: |
Abstract: The aim of the present study was to document ovarian antral follicle dynamics throughout seasonal anoestrus in sheep. Daily transrectal ultrasonography was performed during four 17 day scanning periods from March to July in Western White-faced crossbred ewes. Blood samples were collected each day with ultrasonographic scanning for measurement of serum concentrations of FSH, oestradiol and progesterone. Blood samples were also taken every 15 min for 6 h, mid-way through each period of ultrasonographic examination, to determine the patterns of secretion of gonadotrophic hormones. Hormonal data were then related to observed changes in follicular populations and the patterns of antral ovarian follicle turnover. Ultrasonography showed that the ovaries of anoestrous ewes remained active and that the largest ovarian antral follicles grew to a periovulatory size (> or = 5 mm in diameter) at all stages of anoestrus. The total number of all ovarian follicles > or = 3 mm in diameter was lower during early anoestrus compared with at mid-anoestrus because of a significantly smaller number of small (3 mm) and medium (4 mm) ovarian follicles. The largest ovarian follicles (attaining > or = 5 mm in diameter before regression) exhibited a wave-like pattern of growth; an average of three waves of follicular development were recorded in sheep during each of the four 17 day scanning periods in anoestrus, with follicular waves emerging approximately every 5 days. This rhythmic pattern of follicular emergence was found to be associated with the occurrence of fluctuations in serum FSH concentrations. The growth rate of the largest follicles of the wave increased significantly from early to late anoestrus in sheep. In addition, ovarian follicles not growing beyond 3 mm in diameter showed organized patterns of growth and regression; their numbers tended to be lower (P = 0.09) at 3 days before and on the day of follicular wave emergence. Some ewes were seen to maintain synthesis of progesterone throughout anoestrus. This submaximal progesterone secretion tended to occur at irregular intervals and was not coupled with changes in concentrations or patterns of gonadotrophin release, ovulations or detectable morphological luteinization of ovarian antral follicles. It was concluded that the growth of ovarian antral follicles to an ovulatory size was maintained throughout anoestrus in ewes, with a transient shift in the number of small and medium-sized follicles during mid-anoestrus, and that the periodic emergence of waves of large follicles (> or = 5 mm in diameter) occurred in synchrony with an endogenous rhythm of FSH secretion. MenosAbstract: The aim of the present study was to document ovarian antral follicle dynamics throughout seasonal anoestrus in sheep. Daily transrectal ultrasonography was performed during four 17 day scanning periods from March to July in Western White-faced crossbred ewes. Blood samples were collected each day with ultrasonographic scanning for measurement of serum concentrations of FSH, oestradiol and progesterone. Blood samples were also taken every 15 min for 6 h, mid-way through each period of ultrasonographic examination, to determine the patterns of secretion of gonadotrophic hormones. Hormonal data were then related to observed changes in follicular populations and the patterns of antral ovarian follicle turnover. Ultrasonography showed that the ovaries of anoestrous ewes remained active and that the largest ovarian antral follicles grew to a periovulatory size (> or = 5 mm in diameter) at all stages of anoestrus. The total number of all ovarian follicles > or = 3 mm in diameter was lower during early anoestrus compared with at mid-anoestrus because of a significantly smaller number of small (3 mm) and medium (4 mm) ovarian follicles. The largest ovarian follicles (attaining > or = 5 mm in diameter before regression) exhibited a wave-like pattern of growth; an average of three waves of follicular development were recorded in sheep during each of the four 17 day scanning periods in anoestrus, with follicular waves emerging approximately every 5 days. This rhythmic pattern ... Mostrar Tudo |
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Palavras-Chave: |
Anestro; Dinamica folicular; Folículo; FSH; Funcao ovariana. |
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Thesagro: |
Estradiol; Ovário; Ovino; Reprodução Animal. |
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Thesaurus Nal: |
Anestrus; Endocrinology; Females; Follicle-stimulating hormone; Luteinizing hormone; Pituitary gonadotropins; Progesterone; Reproduction; Sheep; Ultrasonography. |
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Categoria do assunto: |
-- |
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Marc: |
LEADER 03686naa a2200385 a 4500
001 1528867
005 2002-11-22
008 1998 bl uuuu u00u1 u #d
100 1 $aBARTLEWSKI, P. M.
245 $aOvarian follicular dynamics during anoestrus in ewes.$h[electronic resource]
260 $c1998
520 $aAbstract: The aim of the present study was to document ovarian antral follicle dynamics throughout seasonal anoestrus in sheep. Daily transrectal ultrasonography was performed during four 17 day scanning periods from March to July in Western White-faced crossbred ewes. Blood samples were collected each day with ultrasonographic scanning for measurement of serum concentrations of FSH, oestradiol and progesterone. Blood samples were also taken every 15 min for 6 h, mid-way through each period of ultrasonographic examination, to determine the patterns of secretion of gonadotrophic hormones. Hormonal data were then related to observed changes in follicular populations and the patterns of antral ovarian follicle turnover. Ultrasonography showed that the ovaries of anoestrous ewes remained active and that the largest ovarian antral follicles grew to a periovulatory size (> or = 5 mm in diameter) at all stages of anoestrus. The total number of all ovarian follicles > or = 3 mm in diameter was lower during early anoestrus compared with at mid-anoestrus because of a significantly smaller number of small (3 mm) and medium (4 mm) ovarian follicles. The largest ovarian follicles (attaining > or = 5 mm in diameter before regression) exhibited a wave-like pattern of growth; an average of three waves of follicular development were recorded in sheep during each of the four 17 day scanning periods in anoestrus, with follicular waves emerging approximately every 5 days. This rhythmic pattern of follicular emergence was found to be associated with the occurrence of fluctuations in serum FSH concentrations. The growth rate of the largest follicles of the wave increased significantly from early to late anoestrus in sheep. In addition, ovarian follicles not growing beyond 3 mm in diameter showed organized patterns of growth and regression; their numbers tended to be lower (P = 0.09) at 3 days before and on the day of follicular wave emergence. Some ewes were seen to maintain synthesis of progesterone throughout anoestrus. This submaximal progesterone secretion tended to occur at irregular intervals and was not coupled with changes in concentrations or patterns of gonadotrophin release, ovulations or detectable morphological luteinization of ovarian antral follicles. It was concluded that the growth of ovarian antral follicles to an ovulatory size was maintained throughout anoestrus in ewes, with a transient shift in the number of small and medium-sized follicles during mid-anoestrus, and that the periodic emergence of waves of large follicles (> or = 5 mm in diameter) occurred in synchrony with an endogenous rhythm of FSH secretion.
650 $aAnestrus
650 $aEndocrinology
650 $aFemales
650 $aFollicle-stimulating hormone
650 $aLuteinizing hormone
650 $aPituitary gonadotropins
650 $aProgesterone
650 $aReproduction
650 $aSheep
650 $aUltrasonography
650 $aEstradiol
650 $aOvário
650 $aOvino
650 $aReprodução Animal
653 $aAnestro
653 $aDinamica folicular
653 $aFolículo
653 $aFSH
653 $aFuncao ovariana
700 1 $aBEARD, A. P.
700 1 $aCOOK, S. J.
700 1 $aRAWLINGS, N. C.
773 $tJournal of Reproduction and Fertility$gv. 113, n. 2, p. 275-285, 1998.
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