The non-luteolytic effect of prostaglandin F(2)alpha at the beginning of the bovine oestrous cycle: the role of oestrogen?
After the preovulatory gonadotrophin surge, antral follicles ovulate or become atretic; whatever their evolution, they stop secreting oestradiol. Since it was demonstrated that oestrogens were necessary for luteolysis to occur after PGF(2)alpha treatment, their absence could explain the non-luteolytic effect of PGF(2)alpha injected early in the cycle. Thus, cyclic cows received a PGF(2)alpha analogue and oestradiol valerate together on day 3. This treatment did not affect the life span of the corpus luteum. The absence of oestrogens in the blood does not explain the failure of PGF(2)alpha to cause luteolysis in young corpora lutea.
Saumande
J
J
INRA, Reproductive Physiology, Nouzilly, France.
Chupin
D
D