Effects of Intrafollicular Injection of Gonadotrophins on Ovulation or Luteinization of Ovarian Follicle

A method has been developed in rabbits by which hormones can be injected directly into the follicular antrum without impairing the ability of the follicle to ovulate. When 10 ng of LH or 100 ng of FSH are injected into single follicles they ovulate, as determined by ovulation points and by the demonstration of ova in the oviduct. Saline-treated adjacent follicles do not ovulate. The rate of ovulation is not significantly different from that obtained by the intravenous administration of these hormones. Ovulation occurs 10.5 h after treatment. Prolactin, TSH, or saline were unable to induce ovulation. The contamination of FSH by LH cannot account for the ability of FSH to cause ovulation. Combinations of 75 ng of FSH and 5 ng of LH, doses which do not cause ovulation when the hormones are given separately, are effective in inducing ovulation. It is concluded that the ovulation-inducing hormone is a complex of FSH and LH. When less than ovulatory doses of LH (1–5 ng) or of FSH (10–20 ng) are injected, the treated follicles invariably luteinize in the presence of the ovum. Ovulated or luteinized follicles produce amounts of progesterone comparable to corpora lutea (CL) of pseudopregnant rabbits.