Data/hora: 13/06/2024 00:40:45

Biblioteca(s): | Embrapa Caprinos e Ovinos.
Data corrente: | 06/04/2005
Data da última atualização: | 06/04/2005
Autoria: | EVANS, A. C. O.; DUFFY, P.; QUINN, K. M.; KNIGHT, P. G.; BOLAND, M. P.
Título: | Follicular waves are associated with transient fluctuations in FSH but not oestradiol or inhibin-A concentrations in anoestrous ewes.
Ano de publicação: | 2001
Fonte/Imprenta: | Animal Science, v. 72, pt 3, p. 547-554, 2001.
Idioma: | Inglês
Conteúdo: | The aim roas to examine statistically the changes among days in the numbers of follicles relative to the growth of large follicles to test the hypothesis that follicular development occurs in a wave-like fashion in anoestrous ewes. The relationships among the patterns of circulating concentrations of FSH, oestradiol and inhibin-A and the pattern of follicular growth as well as relationships among follicular fluid steroid and inhibin-A concentrations were also studied. The avaries of 11 ewes were examined daily using transrectal ultrasonography for 14 days and blood samples were collected every 8 h for 9 days. Five ewes were ovariectomized on the last day of ultrasound scanning. One to three identified follicles (a cohort) emerged every 2 to 5 days (mean 2.9 (s.e.0.2) days) in individual ewes. The numbers of 4 and 5 mm follicles were fewest (P < 0.05) before and greatest (P < 0.05) 1 day after cohort emergence. This change in the numbers of follicles indicates a wave-like pattern of follícular growth. FSH concentrations were greatest (P < 0.05) on the day before wave emergence and lowest (P < 0.05) on the day of wave emergence. Peripheral concentrations of oestradiol and inhibin-A did not fluctuate (P > 0.05) in association with the emergence of follicular waves. The foIlicles that were collected at ovariectomy originated from one of three different waves. Oestradiol and inhibin-A concentrations in foIlicular fluid and the oestradiol-to-progesterone ratio were not different among the largest foIlicles of successive waves, when foIlicles were collected at the same time, indicating thàt new waves of foIlicles developed before the demise of old waves. In conclusion, waves of foIlicles emerged about every 3 days in anoestrous ewes (defined as significant changes in numbers of follicles) and roere associated with fluctuations in FSH concentrations but not peripheral oestradiol or inhibin-A concentrations. New foIlicular waves also emerged in the presence of steroidogenically active (positive oestradiol-to-progesterone ratio), inhibin-A producing foIlicles from a previous wave suggesting that foIlicles do not exert functional dominance during the non-breeding season.
Palavras-Chave: | Folículo; FSH; Inibidor.
Thesagro: | Endocrinologia; Estradiol; Estrógeno; Hormônio; Ovino; Reprodução Animal.
Categoria do assunto: | --
Registro original: | Embrapa Caprinos e Ovinos (CNPC)
Exemplares: | CNPC - (17612-1) - ADC - AP - -- -  -  - v.72,p.547 - DIS