Progesterone and oestradiol-17 beta concentration profiles throughout the reproductive cycle in harbour seals (Phoca vitulina)

Journal of Reproduction and Fertility
Peter J H Reijnders


Serum samples of harbour seals kept in captivity were analysed for progesterone and oestradiol-17 beta. The hormone profiles obtained were used to describe a complete reproductive cycle. A clear peak in oestradiol values, indicative of ovulation, was followed by elevated concentrations of progesterone. Implantation probably occurred 3-3.5 months thereafter. Progesterone concentrations rose significantly in the last 3-4 months of gestation, whereas oestradiol concentrations gradually increased after implantation. Lactational oestrus was marked by a peak of oestradiol on average 25 days after parturition and lactation lasted 4-5 weeks. Previous pregnancy had a marked influence on the timing of oestrus; females with offspring started a new reproductive cycle about 14 days later than previously non-pregnant seals. No differences in timing of parturition between the 2 groups were observed. This was probably the result of a flexible period of delayed implantation.


Jun 9, 2000·Annual Review of Physiology·M B Renfree, G Shaw
Mar 6, 2010·The Journal of Reproduction and Development·Etsuko Katsumata
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Sep 22, 2009·The Anatomical Record : Advances in Integrative Anatomy and Evolutionary Biology·Kathleen M ColegroveLinda J Lowenstine
Feb 29, 2020·Archives of Environmental Contamination and Toxicology·G M TroisiM Nyman

Related Concepts

Lactation, Prolonged
Embryo Implantation Inhibition
Progesterone, (17 alpha)-Isomer
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