Effect of luteinizing hormone on ovarian release of steroids: ovarian vein-sampling technique in conscious gilt.

After ventral midline laparotomy was done, silastic tubing was inserted into the ovarian vein through a cranial branch of the uterine vein. The free end of the silastic tubing was exteriorized through a perforation of the dorsal wall of the vagina and then passed to the outside of the vulva. The free end of the tubing was sutured to the skin approximately 3 cm lateral to the ventral aspect of the vulva. In the ovarian vein of the sow, the plasma concentration of ovarian steroids was 1.5 to 4.0 times greater than that in peripheral blood, thus making possible the detection of changes not found in peripheral plasma samples. Blood samples were taken immediately after surgical placement of the sample collection tube for a 4-month period from unstressed gilts. Surgical stress seems to increase significantly the release of steroids into the ovarian vein. After the luteinizing hormone injection, progestin but not estrogen was consistently released into the ovarian vein.