Abstract
Rabbit preimplantation embryos were flushed from the reproductive tract at 24 hr (1- to 2-cell stage), 48 hr (morula), 72 hr (morula), 96 hr (blastocyst), 120 hr (blastocyst), and 144 hr (blastocyst) post coitum. At 168 hr (early postimplantation period), gestation sacs were excised, frozen, and sectioned in a cryostat. Delta5-3beta-Hydroxysteroid dehydrogenase [3(or 17)beta-hydroxysteroid:NAD(P) oxidoreductase, EC 1.1.1.51] activity was determined histochemically in whole preimplantation embryos and in sectioned postimplantation embryos. 3beta-Hydroxysteroid dehydrogenase activity began at 48 hr and was sustained through the late blastocyst stage (144 hr), with the exception of a brief drop, possibly cessation, of activity at 72 hr. There was no activity at 168 hr. Since 3 beta-hydroxysteroid dehydrogenase is a key enzyme in the metabolism of steroid hormones, its presence is strong evidence for steroidogenesis. Only 144-hr preimplantation embryos were used to determine 17 beta-hydroxysteroid dehydrogenase (estradiol-17beta:NAD 17-oxidoreductase, EC 1.1.1.62) activity, which was present, suggesting synthesis of estrogen. By means of radioimmunoassay, 144-hr preimplantation embryos were found to contain estradiol-17beta. Other authors have shown that rabbit blastocysts contain progesterone and other steroids, and these embryos can synthesize steroids from non-steroid and steroid precursors. Therefore, our results plus those of others prove that rabbit preimplantation embryos synthesize steroid hormones. Our present and previous results (with rats, hamsters, and mice) suggest that the steroid hormones synthesized by the embryo are critical for preimplantation embryogenesis and for implantation of the lbastocyst.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Dey S. K., Dickmann Z. Delta5-3beta-hydroxysteroid dehydrogenase activity in rat embryos on days 1 through 7 of pregnancy. Endocrinology. 1974 Jul;95(1):321–322. doi: 10.1210/endo-95-1-321. [DOI] [PubMed] [Google Scholar]
- Dey S. K., Dickmann Z. Estradiol-17beta-hydroxysteroid dehydrogenase activity in preimplantation rat embryos. Steroids. 1974 Jul;24(1):57–62. doi: 10.1016/0039-128x(74)90045-2. [DOI] [PubMed] [Google Scholar]
- Dickmann Z., Dey S. K. Evidence that delta5-3beta-hydroxysteroid dehydrogenase activity in rat blastocysts is autonomous. J Endocrinol. 1974 Jun;61(3):513–514. doi: 10.1677/joe.0.0610513. [DOI] [PubMed] [Google Scholar]
- Dickmann Z., Dey S. K. Steroidogenesis in the preimplantation rat embryo and its possible influence on morula-blastocyst transformation and implantation. J Reprod Fertil. 1974 Mar;37(1):91–93. doi: 10.1530/jrf.0.0370091. [DOI] [PubMed] [Google Scholar]
- Dickmann Z., Sen Gupta J. Delta5-3beta-hydroxysteroid dehydrogenase and estradiol-17beta-hydroxysteroid dehydrogenase activity in preimplantation hamster embryos. Dev Biol. 1974 Sep;40(1):196–198. doi: 10.1016/0012-1606(74)90119-5. [DOI] [PubMed] [Google Scholar]
- Exley D., Johnson M. W., Dean P. D. Antisera highly specific for 17 -oestradiol. Steroids. 1971 Nov;18(5):605–620. doi: 10.1016/0039-128x(71)90073-0. [DOI] [PubMed] [Google Scholar]
- Haour F., Saxena B. B. Detection of a gonadotropin in rabbit blastocyst before implantation. Science. 1974 Aug 2;185(4149):444–445. doi: 10.1126/science.185.4149.444. [DOI] [PubMed] [Google Scholar]
- Hotchkiss J., Atkinson L. E., Knobil E. Time course of serum estrogen and luteinizing hormone (LH) concentrations during the menstrual cycle of the rhesus monkey. Endocrinology. 1971 Jul;89(1):177–183. doi: 10.1210/endo-89-1-177. [DOI] [PubMed] [Google Scholar]
- Seamark R. F., Lutwakmann C. Progestins in rabbit blastocysts. J Reprod Fertil. 1972 Apr;29(1):147–148. doi: 10.1530/jrf.0.0290147. [DOI] [PubMed] [Google Scholar]