[The first stages of ovum implantation in rats castrated before noon on the 5th day of gestation].

Ovariectomy performed on the 5th day of gestation before noon does not stop the first stages of ovoimplantation in the Rat. On the morning of the 6th day the reactivity to trypan blue is increased. Most of the blastocysts are well fixed in their implantation chamber.

[Effect of different estro-progesterone sequences on nidation of dormant blastocysts administered in diapause in ovariectomized rats].

The hormonal condition permitting delayed nidation in rats ovarectomized on day 4 or 5 of pregnancy was studied by administering progesterone and estradiol in differents sequences between days 9 and 14. The best result was obtained when progesterone was given 3 days before an estrogen-progesterone association. The same treatment induced delayed nidation in rats receiving Reserpine and ovariectomized day 5, but not when progesterone and estradiol were present day 4.

[Does estradiol act in a unique way during progestation in the female rat? I. Uptake and retention of estradiol 17beta in the uterus of castrated rats under the influence of uterine distension].

In castrated female rats, uterine distension resulted in an increased uptake of tritiated oestradiol within the period studied (from 10 minutes to 24 hours after distension), whereas progesterone 14C incorporation was not increased. Using cold hormones (progesterone or oestradiol) before injection of radioactive ones, wer were able to demonstrate the specificity of this uptake 3.5 hours or 24 hours after initiation of distension.

[Relative concentration of deoxyribonucleic acid in the experimental deciduoma and the blastocyst of female rats: cytophotometric study].

Polyploidy level of experimentally induced deciduomata was determined by cytophotometric measures of DNA-Feulgen, with the "Ultramikrospektrophotometer UMSP Zeiss" by scanning. The antimesometrial tissue reached 32 n, 72 H after the uterine trauma, whereas the mesometrial part did not exceed a 4 n polyploidy level. With the same technics we studied the ovarian hormone, its action upon the blastocyst cellular cycle.