Reversibility of Hyalinization I N the Mouse Uterus Produced by Injections of Estrogen, and T H E Changes in the Mammary Gland and Ovaries after Cessation of Injections

In former investigations (1) we observed the deposition of a hyaline substance in the connective tissue of the uterine mucosa and muscularis of mice injected with large doses of estrogen for a period of two months or longer. This hyaline material acted in certain respects like a foreign body, in some instances causing the formation of epithelioid and small giant cells which helped in its absorption as well as in its invasion and replacement by connective tissue. Absorption was accompanied or followed, however, by the deposition of new hyaline, and in this way the abnormal condition of the uterine connective-tissue stroma and muscularis was perpetuated. There was evident a tendency of the hyaline to persist, especially at the borderlines separating different structures, such as blood vessels and glands, from the surrounding stroma. In the uterine cervix conditions were similar to those observed in the uterus, but in certain parts of the vagina, especially around the vaginal folds and between folds and cervix, a rarefaction of the tissue took place, apparently due to the occurrence of liquefaction processes in the hyaline material or to its deposition in a diluted form. As to the chemical nature of the substance deposited in the uterus, cervix, and vagina, the reactions for amyloid were negative; on the other hand, it stained strongly with eosin. In further tests it was found to stain red with Van Gieson stain and strongly blue with Mallory’s connective-tissue stain. It did not take Weigert’s stain for fibrin. In these reactions the behavior of the hyaline substances deposited in the uterus and in certain parts of the cervix and vagina of the mouse following injections of large doses of estrogen is identical with that of collagen. Under these conditions it seemed to be of interest to determine the fate of this hyaline material when the injections of estrogen were discontinued. Would the hyaline substance persist, or would it be replaced by connective tissue? In the latter case the question remained as to the character and origin of the connective tissue and the time required for the substitution to be complete. In addition we desired to study the changes in certain other organs, as the mammary gland and ovaries, the thyroid and adrenal glands, during the injection of estrogen and after its cessation, in order to obtain new data concerning the effects of the hormone on these organs. We hoped thus