Abstract
It has been previously reported 1 that injections of an oestrin-free placenta extract, containing the A. P. L. factor, into immature female rats induced a marked increase in the weight of the ovaries and a moderate increase in the weight of the pituitaries. Histologically, the pituitaries of the injected rats showed a slight to moderate decrease in the level of the eosinophiles; a considerable number showed evidence of granular loss. The most evident changes were found in the basophiles, which showed marked evidence of granular depletion.
Injection of pregnancy urine extracts into immature female rats gives similar results. Thirty rats, 21 to 25 days old, were given daily injections of pregnancy urine extract† (25 to 75 R. U. daily for 6 to 15 days). Twenty-eight littermate sisters served as controls. The ovaries of the injected rats weighed from 50 to 80 mg., while those of the controls weighed from 15 to 25 mg. The pituitaries of the injected animals were usually, but not invariably, increased in weight. Complete serial sections of all pituitaries were cut, at 2 micra, in the horizontal plane. One section from each ribbon of 15 was mounted and stained. Cell counts were made on 5 sections, equidistant apart from each set of serial sections (110,039 cells were counted on the 208 sections studied). The anterior lobes of the injected animals were definitely altered from those of the controls. The eosinophiles were almost invariably reduced in number, and many of them were swollen and showed granular loss. The most marked changes were found in the basophiles, which showed reduction of granules. There was an increase in the percentage of the chromophobes. Mitoses were found in the chromophobes and eosinophiles of both the injected and control animals; they were more abundant in the injected animals. Mitotic division has never been observed in the basophiles.
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