Abstract
Changes in the anterior lobe of the pituitary after administration of the anterior pituitary-like hormone (A.P.L.) of pregnancy urine or placenta have been observed by numerous investigators, 1 , 2 , 3 but their results are contradictory, both as regards the histological nature of the changes thus produced and the effectiveness or ineffectiveness of A.P.L. in the male.
Zondek 3 found that when prolan is given to female rats over a long period the ovaries, which have increased in size in the beginning, will become smaller again. These observations have been confirmed in this Department, and it has also been found that the same retrogression in size takes place in the sex organs of the male if A.P.L is given over a very long period. 4
We thought that this decrease in sensitivity to A.P.L. which sets in gradually in chronic experiments might be at least partly responsible for the discrepancies in the results of those investigators who studied the effect of A.P.L. on the pituitary. Our experiments seem to confirm this view. We found in several series of experiments in which injections were given from the 27th to the 67th day of life, that the size of the pituitary runs parallel to the size of the ovaries in the A.P.L. treated female rat. In 16 rats observed at the time when the enlargement of the ovaries was most conspicuous (0.547-0.616 gm. as compared with 0.032 in the untreated control females of the same age) the pituitary was also at its maximum size (0.0115-0.012 gm. as compared with 0.004-0.0045 gm. in the control animals). This increase in weight is due solely to the enlargement of the anterior lobe.
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