THE PHYSIOLOGY OF PREGNANCY IN THE RAT: FURTHER DATA ON THE PASSAGE OF HORMONES VIA THE PLACENTA AND THE MOTHER'S MILK

¹ The Institute of Animal Genetics, Edinburgh University

1. The effect of the ante-natal administration of strone on the morphological development of the female ftus (rat) was further examined: the minimum amount of strone capable of modifying ftal morphology was ascertained, and the earliest day at which the effect could be induced. Large amounts of strone did not cause further abnormalities or affect the male in a similar manner.

2. Experiments with preparations of various ductless glands failed to demonstrate that the action of strone was an indirect one.

3. Other compounds related to strone in chemical structure were examined: the di-hydroxy derivative of androsterone (male hormone) was found to affect the morphology of the female ftus in the same way as strone.

4. The benzoate of strone has a similar action on the ftus; the effective amounts of the two forms are compared. The suckling female also is capable of modification when the benzoate is injected into the lactating mother.

5. The urogenital region of the female rat is capable of modification by the direct injection of strone on the day of birth.

6. The subsequent reproductive history of litters which came under the influence of strone in the early stages of development is examined.

7. The significance of a similar action on the ftus by both male and female hormones is discussed.

8. The results obtained with the benzoate of strone suggest that the concentration reached by the hormone is of more importance in determining the effect on the ftus than the duration of its activity; they indicate that the effect is brought about by the hormone in its physiologically active form.

Note:

The expenses of this investigation were defrayed by grants from the Carnegie Trust and the Medical Research Council. The author desires to acknowledge the supply of strone, strone benzoate, and progestin, by the British Drug Houses, Ltd., at a greatly reduced price; hombreol, by Dr. MacBeth of Organon, and Antuitrin "S," by Parke, Davis & Co., both free of charge; also 1:2 benzpyrene by Union Chimique Belge, Brussels, at cost price.