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PUTTIPONGSE VARAVUDHI and BERTHA L. LOBEL

Summary.

Ergocornine methanesulphonate, in doses which are effective in inhibiting decidualization and nidation, exercised no direct toxic effect on the blastocysts of pregnant rats in which experimental delayed nidation had been induced by hypophysectomy.

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BERTHA L. LOBEL, M. C. SHELESNYAK and LILIANE TIC

Summary.

When pregnant rats are given a single subcutaneous injection of ergocornine methanesulphonate on the 4th day of gestation, physiological indications of changes in the ovary are manifold.

Activities of a number of histochemically demonstrable enzymes were investigated in the ovaries of ergot-treated pregnant rats. The enzymes included Δ5-3β-hydroxysteroid dehydrogenase, succinic dehydrogenase, alkaline and acid phosphatase and adenosine-triphosphatase.

The ovaries were examined at 2-, 4-, 8- and 24-hr intervals after administration of the drug. Macroscopic and microscopic vascular dilatation and engorgement were seen in the ovaries at 2, 4 and 8 hr and had decreased by 24 hr. Activities of Δ5-3β-hydroxysteroid dehydrogenase and succinic dehydrogenase were histochemically demonstrable in the corpora lutea of gestation as well as other sites in the ovary at 2, 4 and 8 hr after ergocornine. At 24 hr, portions of the corpora lutea of gestation showed necrosis and dissolution of cells and many healthy vesicular follicles had developed. These changes in the ovary (luteolysis in the corpora lutea of gestation and development of follicles to the ovulation stage) form the basis for the physiological effects—interruption of gestation and appearance of oestrus—which occur 2 to 3 days after administration of ergocornine to pregnant rats during progestation.

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PUTTIPONGSE VARAVUDHI, BERTHA L. LOBEL and M. C. SHELESNYAK

Summary.

Successful induction of decidualization on the 4th day of pseudopregnancy (L4) is possible in rats hypophysectomized on L3 of pseudopregnancy (after 19.00 hours). However, in the absence of exogenous hormone, the decidual cell reaction cannot be maintained in the hypophysectomized rat. The effect of hypophysectomy on decidualization which is already established depends upon the time of removal of the pituitary. When hypophysectomy was performed before the 11th day of pseudopregnancy (L11) breakdown and resorption of the deciduomata occurred within 4 days; when hypophysectomy was carried out on L11 or L12, the deciduomata were resorbed more slowly. This relatively prolonged resorption was related to the absence of ovulation at the end of the period of pseudopregnancy in the hypophysectomized rats. The results indicate that no luteotrophic factor of uterine or decidual origin is produced in the pseudopregnant rat bearing deciduomata.