ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
Rats were given single doses of an orally-active estrogen by mouth on days 1-5 of pregnancy. Examination of uteri on day 8 for implantations revealed that the median effective doses for preventing 50% of the eggs shed from implanting were 0.047, 0.050, 0.035, 0.145 and 0.380 mg/kg for days 1, 2, 3, 4 and 5 respectively. It was found that failure of pregnancy after treatment with the minimal 100% effective dose (ED100) on days 1, 2 or 3 was due to expulsion of eggs from the reproductive tract by day 5. Treatment of rats with the ED100 on day 4 caused expulsion of some eggs from the tract by day 5, but also had effects on the uterus: the position of the blastocysts within the lumen was abnormal and their orientation relative to the mesometrial-anti-mesometrial axis disturbed. No decidual reaction was observed on day 6 in such rats or on day 9 in pseudopregnant rats treated similarly and subjected to uterine traumatization on day 5. Treatment with ED100 on day 5 had no effect on egg transport or on the positioning of blastocysts within the lumen on day 6. A decidual reaction was seen around the blastocyst on day 6, but in pseudopregnant rats treated similarly and subjected to uterine traumatization on day 5 no decidual reaction was found on day 9. The pontamine blue reaction was negative in nearly all rats dosed on day 4 and examined on days 6-8. In rats dosed on day 5, however, the blue reaction was negative on day 6, but positive on day 7, i.e., delayed by 24 hours compared to controls and appearing later than the decidual reaction. The blastocysts were unattached in these rats on day 6, but may have attached briefly on day 7 (suggested by the positive blue reaction) and subsequently failed to develop further owing to disappearance of the decidual tissue.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1091620405
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