Abstract
Recent studies in this laboratory have confirmed the results of Payne, Peenan and Cortland, 1 Haterius and Pfiffner, 2 and Macht, Stickels and co-workers 3 on the inhibition of normal ovarian activity by preparations of the corpus luteum.
The experiments herein reported were carried out on our laboratory strain of albino rats. The general plan was to take a series of mature animals and follow the oestrus cycle for a period of time to be certain that all animals were normal. The animals were then to be treated with corpus luteum extracts to determine any effect on the length of the cycle. In certain cases control extracts, prepared from the anterior lobe and thymus and containing approximately the same total solids, were also used.
Due to the well known fact that the length of the cycle is profoundly influenced by the general health and environment of the animal, all precautions were taken to keep the animals under uniform conditions during the course of the experiment. In each experiment a number of rats were used to determine the control cycles, but usually only about 50% of these showed a regular cycle and could be used in the experiment.
The corpus luteum extracts, as well as the control extracts of anterior pituitary and thymus, were prepared by acid alcohol extraction of either fresh glands or carefully desiccated glands with the subsequent conversion of the active material into an aqueous solution. No difference was noticed between the fresh glands and desiccated glands as the source of active material. All injections consisted of 1 cc. of sterile solution and were given intramuscularly.
The rats used in these experiments were from 3 to 4 months old and weighed from 150 to 175 gm. We found that in rats weighing much less than 125 gm. the cycles were too irregular to be used for this work.
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