| Abstract: | The role of estradiol-17 beta (E2) in migration of the porcine embryo was examined (Experiment 1) by observing the distribution of Silastic (polydimethyl siloxane, Medical Adhesive Silicone Type A, Dow Corning) beads impregnated with cholesterol or E2 (n=5 gilts per treatment) after 5 days in utero (Day 12 of the estrous cycle, Day 0=1st day of estrus). Beads impregnated with E2 migrated farther (P less than 0.05) than those impregnated with cholesterol. Twenty additional gilts and sows were used to determine if histamine was involved with intrauterine migration (Experiment 2). On Day 6 of gestation the tip of each uterine horn was exposed and the subserosa of each of 5 gilts was injected with either vehicle, 8 mg of cromolyn sodium (an inhibitor of histamine release) or 8 mg of cromolyn sodium plus 1 mg of histamine. Four days later (Day 10), the excised uterus was examined for migration of embryos. An additional group of 5 gilts received 8 mg of cromolyn sodium on Days 6 and 10 and were examined on Day 12. Results from the second experiment demonstrated that cromolyn sodium treatment alone restricted (P less than 0.05) Day 10 embryos to the tip of the uterine horn but by Day 12 embryos had overcome this restriction. Injection of histamine overcame the inhibitory effects of cromolyn sodium and restored migration of Day 10 embryos. These experiments suggest that both E2 and histamine are involved in intrauterine migration of the porcine embryo. The extent to which these hormones might be interrelated during migration is not fully understood at this time. |
