Abstract
The PGE1, PGE2 and PGF2α were used as the substrates to histochemically demonstrate the activ-ities of prostaglandin dehydrogenases (PGDHs) in intact mouse blastocysts on Day 4 of pregnancy, in delayed implanting blastocysts on Day 10 and those on Day 10 but 18h after the administration of estradiol benzoate. Diformazan granules were deposited by the treatment with NISSEN and ANDERSEN method in the cytoplasm of both trophoblast cells and inner-cell-mass cells of the blastocysts when there was some activity of PGDH present in them. All of the activities of PGDHs in intact blasto-cysts were weak both in the trophoblasts and inner cell masses with the use of any kinds of sub-strates. However, all of the activities of PGDHs in the delayed implanting blastocysts either with or without the administration of estradiol benzoate were strong in the trophoblasts, but negative in the inner cell masses. Considering the present results as well as those on the metabolism of lipids and steroids in delayed implanting mouse blastocysts, the activities of PGDHs in such blastocysts seemed to be concerned with the metabolism of lipids and steroids.
