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

¹ Macaulay Laboratory, Department of Animal Genetics, The University, Edinburgh

The statement of Knaus, that the injection of an extract of the corpus luteum into mature non-pregnant rabbits inhibits the in vitro reaction of the uterus to pituitrin, has been confirmed. Both the oxytocie and pressor fraction of the posterior lobe are inhibited.

Small doses of alpha (strin, in oily solution) do not interfere with the progestational or inhibitory reactions of the corpus luteum hormone; large doses of alpha (more than 3000 mouse units) prevent the progestational reaction, but the pituitrin reaction is still inhibited.

Inhibition of the pituitrin reaction was obtained in several cases with an extract of the human placenta. No proliferation was obtained. The corpus luteum extract was partitioned between petroleum ether and 50 per cent. alcohol. The petroleum ether fraction caused proliferation, but little or no inhibition. The 50 per cent. alcohol fraction, which formed a colloidal solution in water, caused some proliferation and complete inhibition.

Saponification destroyed both the proliferative and inhibitory actions of the corpus luteum extract.

It is suggested that the proliferative and inhibitory actioins of the corpus luteum extract may be due to different factors.

We wish to express our gratitude to Dr. B. P. Wiesner for valuable help and advice in the course of this work.