Determination of the FSH and LH contents of Pituitaries and sera of Dokki-4 laying hens were made at 24, 16 and 8 hours before ovulation. The gonadotrophin-releasing hormone contents of the hypothalamic of such hens were also determind. The weights of the ovaries were recorded with reference to their follicle diameter and ascorbic acid contents of the cellular structures of the greafian follicle wall
The findings indicated a sequence of events characterized by increased depletion of the gonadtrophin-releasing hormone contents of the hypothalami during periods of 24 and 16hours before ovula - tion. Such changes were accompanied with an initial increase in the serum FSH content followed by its decrease giving chance for a subsequent increase in LH content of the serum at a time 16 hours before ovulation. Such an increase in LH activity was accomp anied with ascorbic acid depletion from the follicular wall of the ovaries.At a time 8 hours before ovulation the pituitary and serum gonadotrephin content was low, while the releasing hormone was retained in the hypothalamus.