PREGNANCY CHANGES IN THE RABBIT'S UTERUS AND THEIR RELATION TO ENDOCRINE ACTIVITY. III

¹ Macaulay Laboratory, Institute of Animal Genetics, University of Edinburgh

Daily injections of anterior pituitary lobe substance (together with an antiseptic, quinanil) into mature non-pregnant or pseudopregnant rabbits is followed by luteinisation of the ovaries. The uterus shows typical condition, viz. marked progestational proliferation of the endometrium, but no inhibition of the reaction to pituitrin. This "dissociation" of the uterine responses is never observed during pseudopregnancy or after a single injection of gonadotropic hormone.

The injection of a standard corpus luteum extract into animals receiving daily anterior lobe injections does not, as a rule, bring about inhibition of the pituitrin reaction. The combined daily injection of anterior lobe and -hormone (strin) usually brings about inhibition.

Animals injected intravenously with -free gonadotropic preparations from pregnancy urine for prolonged periods do not show dissociation of the uterine responses.

It is concluded that -hormone is necessary for the development of the inhibitory reaction. A tentative explanation of the results obtained with different gonadotropic preparations is offered.

I am indebted to the Medical Research Council for a grant in aid of this work.