Symplasma formation and decidualization in the pseudopregnant rabbit after intraluminal instillation of tricaprylin

A pure neutral triglyceride, tricaprylin, was injected (Day 0) into isolated segments of the uterus of rabbits in which pseudopregnancy had been induced by i.v. injection of hCG 6 days before. The animals were killed in groups of 3 on Days 1, 2, 3, 4 and 6. Saline, simple ligation of the uterus or uterine trauma were used as control treatments in other uterine segments in the same animals. Extensive symplasma formation in the uterine epithelium of the tricaprylin-treated segments was observed on Days 2 and 3; this had degenerated by Day 4 and was absent by Day 6. Decidualization of the stroma began on Days 3 and 4 and was absent by Day 6. The symplasma formed earlier on the antimesometrial side than it did laterally or mesometrially. Decidualization was maximal mesometrially, intermediate laterally, and absent antimesometrially. Ligation with saline and trauma, but not ligation alone, produced symplasma formation. Decidualization occurred after trauma but not after saline injection or ligation alone.