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Periovulatory Endocrinology and Oocyte Maturation in Unmated Mature Blue Fox Vixens (Alopex lagopus)

Endokrinologi og oocytmodning omkring ovulasjonen hos uparede eldre blårevtisper (Alopex lagopus)


Nine of 10 mature blue fox vixens (Alopex lagopus) in spontaneous oestrus ovulated approximately 2 days after the preovulatory increase in luteinizing hormone (LH). Plasma concentrations of follicle-stimulating hormone and progesterone increased simultaneously with the LH peak, whereas oestradiol-17 β peaked 1 day previously. In the tenth vixen, an LH peak was not observed, and neither visible follicles nor corpora lutea were found in the ovaries 6 days after peak vaginal electrical resistance.

Eggs were ovulated as primary oocytes, but oocyte maturation was initiated within the day of ovulation (2 days after the LH peak). Within the next 2 days (3–4 days after the LH peak) the first polar body was extruded, and the cumulus mass was completely dissociated from the zona pellucida.

The interval between the preovulatory LH peak and initiation of the final oocyte maturation is thus considerably longer in the blue fox than for example in the cow (48–72 h compared with 9–12 h). This suggests that the relationship between these two events is somewhat different in the blue fox.


Hos 9 av 10 eldre blårevlisper i spontan østrus skjedde ovulasjonen ca. 2 døgn etter den preovulatoriske frisetning av lutein i serende hormon (LH). Det ble observert en stigning i follikkelstimulerende hormon og progesteron i plasma samtidig med den preovulatoriske stigning i LH. Østradiol-17 β nådde sitt maksimum ca. 1 døgn før LH maksimum.

Hos den tiende revetispen ble det ikke observert en preovulatorisk LH-stigning. Det ble heller ikke observert follikler eller corpora lutea i ovariene 6 dager etter registrering av maksimal motstandsverdi.

Eggene ble ovulert som primære oocyter omgitt av en tykk cumulusmassc. Første meiotiske deling ble igangsatt innenfor 1 døgn etter ovulasjon, 2 døgn etter LH maksimum. Innenfor 2 døgn etter ovulasjon (3–4 dager etter LH maksimum) kunne førsle pollegeme observeres hös de fleste oocytter, og cumulusmassene var helt dissosiert fra zona pellucida.

Tidsintervallet mellom den preovulatoriske LH-fri set ning og igangsettingen av den endelige oocyttmodning er dermed betydelig lengre hos denne arten enn f. eks. hos ku (ca. 48–72 t mot 9–12 t). Dette kan tyde på at sammenhengen mellom disse begivenhetene er noe annerledes hos blårev.


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We gratefully acknowledge the excellent cooperation of the staff at The Research Farm for Fur-bearing Animals at Heggedal, Norway, we would also like to thank Miss Inger Madsen at the Department of Anatomy, Royal Veterinary and Agricultural University in Copenhagen for preparing the oocytes for electron microscopy and Patricia Simon at The Foundation for Hormonal Research, Fresnes, France, for skilfull technical assistance with the hormone assays.

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Farstad, W., Mondain-Monval, M., Hyttel, P. et al. Periovulatory Endocrinology and Oocyte Maturation in Unmated Mature Blue Fox Vixens (Alopex lagopus). Acta Vet Scand 30, 313–319 (1989).

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  • endocrinology
  • ovulation
  • oocyte maturation