Related Experiment Video
Updated: Jul 12, 2026

Minimally Invasive Embryo Transfer and Embryo Vitrification at the Optimal Embryo Stage in Rabbit Model
Published on: May 16, 2019
STS 557, a new orally active progestin with antiprogestational and contragestational properties in rabbits
Abstract:
STS 557 (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4.9(10)-diene-3-one) is a potent progestin. This compound was 10 times as potent as the standard levonorgestrel as judged by the classic Clauberg-McPhail Assay. The antiprogestational response is significant when STS 557 treatment starts 2 days before progesterone administration. It does not disturb the priming activity of estradiol. This compound alone is adequate for endometrial priming. Early pregnancy is maintained in ovariectomized does. Administration on day 1 of pregnancy reduces the number of implantations. In comparison with chlormadinone acetate and d-norgestrel, only STS 557 treatment causes complete inhibition of egg fertilization.
More Related Videos
Related Concept Videos
Antiplatelet Drugs: Prostaglandin Synthesis, P2Y12 and Glycoprotein IIb/IIIa Inhibitors
Prostaglandin synthesis inhibitors, exemplified by the widely known aspirin, wield their power by irreversibly acetylating...
Treatment for Pulmonary Arterial Hypertension: Prostacyclin Receptor Agonists
These agonists bind to the IPR receptor situated on the plasma membrane of the pulmonary artery smooth muscle cells. This binding triggers a cascade of reactions known as the GS-AC-cAMP-PKA pathway. This pathway results in the relaxation of smooth muscle...
Drugs for Peptic Ulcer Disease: Prostaglandin Analogs as Mucosal Protective Agents
Non-steroidal anti-inflammatory drugs (NSAIDs) can induce peptic ulcers by inhibiting cyclooxygenase, decreasing...
Intrauterine Drug Delivery Systems

