Proceedings: Two theories: the preimplantation embryo is a source of steroid hormones controlling (1) morula-blastocyst transformation and (2) implantation

Binding of Oestradiol to Rabbit Blastocysts and Its Possible Role in Implantation

“…Our data suggest that oestradiol bound to the blastocyst may act as a local signal to the uterus. In this context, recent reports ofoestradiol synthesis by pig blastocysts (Perry, Heap & Amoroso, 1973) and the presence of 3/J-hydroxysteroid dehydrogenase in rat blastocysts (Dickmann & Dey, 1973) are of considerable interest.…”

Histochemical studies of 5-3 -, 20 - and 20 -hydroxysteroid dehydrogenases and possible progestagen production in hamster eggs

“…Using dehydroepiandrosterone as the substrate, Dickmann and his colleagues (Dickmann & Dey, 1973& Dey, , 1974aDickmann & Gupta, 1974;Dey & Dickmann, 1974;Dickmann et al, 1975a, b) demonstrated A5-3ß-HSD in tubai eggs of rats, hamsters and rabbits, and reported that the enzyme activity first appeared at the stage of morula-blastocyst transformation, and suggested that steroid hormones produced by the eggs at this stage controlled this transformation step. Dickmann & Dey (1974b) further examined the influence of (1) ligation of the uterotubal junction, (2) hypophysectomy, and (3) ovariectomy, and stated that A5-3ß-HSD activity in blastocysts was autonomous because none of these treatments had any effect.…”

“…The three enzymes investigated were: A5-3ß-hydroxysteroid dehydrogenase (A5-3ß-HSD) using pregnenolone as the substrate and NAD as the cofactor, 20a-hydroxysteroid dehydrogenase (20a-HSD) using 20a-hydroxypregn-4-en-3-one and NADP, and 20ß-hydroxysteroid dehydrogenase (20ß-HSD) using 20ß-hydroxypregn-4-en-3-one and NAD respectively. To detect these enzymes a slight modification of the method used by Dickmann & Dey (1973) was employed: several sets of eggs from every developmental stage were placed into a solution containing 1-8 mg substrate (Sigma Co.) which had been dissolved in 0-5 ml acetone, 40 mg cofactor (Sigma Co.), 2-0 mg nitroblue tetrazolium (Sigma Co.), and 10 ml 0-1 M-phosphate-buffer solution at pH 7-5. Eggs incubated in a medium containing the substrate solvent, acetone, but devoid of the substrates and NADPH were observed as controls.…”

“…The steroid dehydrogenases, A5-3ß-hydroxysteroid dehydrogenase and 17ß-hydroxysteroid dehydrogenase, have been demonstrated histochemically in the eggs of rats, hamsters and rabbits using dehydroepiandrosterone and oestradiol-17ß respectively as the substrates (Dickmann & Dey, 1973& Dey, , 1974aDickmann & Gupta, 1974;Dey & Dickmann, 1974;Dickmann, Dey & Gupta, 1975a, b).…”

Influence of the Trophoblast Upon Differentiation of the Uterine Epithelium During Implantation in the Mouse

“…It could be physical contact of the trophoblast on the epi¬ thelial surface or the passage of a chemical substance from the blastocyst. The former seems more likely in view of the finding that oil on the surface of the uterine epi¬ thelium induces a similar change, although the possibility that the blastocyst might secrete steroid hormones which influence the epithelium cannot be excluded (Dickman & Dey, 1973).…”