The presence of 17β‐hydroxysteroid dehydrogenase activity in preimplantation rat and mouse blastocysts

Abstract

When Day 5 rat blastocysts and Day 4 and 5 mouse blastocysts were cultured in 53 microliters of medium containing 1340 or 2680 pg [3H]estradiol (E2), large amounts of [3H]estrone (E1) were detected in the medium at daily intervals for up to 5 days. This indicates the presence of 17 beta-hydroxysteroid dehydrogenase in the embryos. The activity was higher at a higher concentration of E2 and was also higher in mouse than in rat blastocysts. In the mouse, the activity was higher in Day 5 than Day 4 blastocysts during the first day in culture; then it decreased in Day 5 but increased in Day 4 blastocysts. The importance of E2 in embryonic development and implantation as suggested by others may be related to the activity of 17 beta-hydroxysteroid dehydrogenase.

Conversion of pregnenolone to progesterone by mouse morulae and blastocysts

“…Mature CF-1 female mice purchased from Charles River Breeding Laboratories (Wilmington, MA, USA) were caged in animal quarters at 20^23°C, with lights on from 07:00 to 19:00 h EST. They were superovulated with gonadotrophins and mated (Wu & Lin, 1982). The morning of finding vaginal plugs was considered Day 1 of pregnancy.…”

Role of embryonic oestrogen in rabbit blastocyst development and metabolism

“…Mammalian embryos have been shown to possess the steroidogenic enzymes, A\3ß-hydroxysteroid dehydrogenase (A5,3ß-HSD) and 17ß-hydroxysteroid dehydrogenase (17ß-HSD) first detected histochemically (Dickmann, Dey & Sengupta, 1976). Biochemically, 17ß-HSD was detected by the conversion of [3H]oestradiol-17ß to [3H]oestrone in mouse and rat blastocysts grown in vitro (Wu & Lin, 1982a). The rabbit blastocyst has been extensively analysed.…”