Annual cycle of plasma luteinizing hormone concentrations in wild mallard drakes

The Journal of Experimental Zoology
E HaaseE Paulke

Abstract

Plasma LH concentrations were followed in 9 individually marked wild mallard drakes in Kiel (54 degrees N) for one year at monthly intervals. Mean LH levels increased during the spring and reached the annual maximum in April and May. In June when testicular regressions occurs, the LH titer sharply decreased and was lower than at any other phase of the annual cycle. In late fall mean plasma LH concentrations increased and, whilst not reaching the values observed during the breeding season, remained relatively high during the winter. Thus, in the mallard LH can be released under short and long daily photo-periods.

References

May 1, 1974·Proceedings of the National Academy of Sciences of the United States of America·B K FollettD S Farner
Nov 1, 1972·British Poultry Science·C G Scanes, B K Follett
Feb 1, 1972·The Journal of Endocrinology·B K FollettF J Cunningham

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Citations

Jul 1, 1983·Journal of Steroid Biochemistry·E Haase
Nov 1, 1989·General and Comparative Endocrinology·C K BluhmW H Burke
Jan 1, 1982·General and Comparative Endocrinology·E HaaseE Paulke

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