Histochemical Detection of NADP-Dependent Prostaglandin Dehydrogenase in Preimplantation Rabbit Embryos

Abstract

Using prostaglandin (PG) E₂ as the substrate, the activity of NADP-dependent 15-hydroxyprostaglandin dehydrogenase (type II PGDH) in preimplantation rabbit eggs and embryos was histochemically investigated, and the metabolism of PGE₂ in them was discussed. The eggs and embryos observed were at 1-cell (unfertilized and pronuclear) to 8-cell, morula and blastocyst stages. Type II PGDH, as well as NAD-dependent PGDH (type I PGDH), was histochemically detected by the method of Nissen and Andersen (1968). The activity of the type II PGDH was strong in the eggs at 1-cell stage, strong to weak in the eggs at 2-cell stage, and weak from 4-cell eggs to the blastocyst stage. The diformazan granules showing the presence of type II PGDH activity were spread evenly throughout the cytoplasm of eggs and embryos at the stages of 1-cell through morula. Blastocysts also presented such granules spread evenly throughout the cytoplasm of both trophoblast and inner-cell-mass cells. The intensity and the distribution of the type I PGDH activity in the eggs and embryos were similar to those of the type II PGDH activity. These results thus seem to point out that rabbit eggs and embryos do have type II PGDH, as well as type I PGDH which has widely been found in different mammalian embryos.