The estrous cycles of the rats used in this study were altered by electric shocks given, at three day intervals or by subcutaneous injections of 1.0 ml. of 3% formalin every other day. In order to observe the effects of sexual hormones on these altered estrous cycles, one or two rat units of estrogen or prehormone(FSH) were given every day or every other day. This was started ne week , prior to the stress exposures in one group. Another group was given* the hormones--simul´ eously with the stresses, another one week after the diestrous phase induced by the strasses. Th results
obtained are as follows.
Effects on the estrous cycle:
By administration of estrogen; whenever it is given, the abnormal, irregular cycles; or particularly those with prolonged diestrous phase induced by the stresses, are promptly changed into cycles with prolonged estrous phase. This change can be easily induced by administration of only one rat unit of estrogen every other day. On the other hand, daily administration of one rat unit of prehormone prior to or simultaneous with the stresses can prevent the rats from having the abnormal cycle. If prehormone is administrated after one week of abnormal diestrous phase induced .by the stresses, the estrous cycle of the rats does not appear.
Histological changes in the ovaries:
In the ovaries of the rats exposed to the stresses, retardation in maturation of Graafian follicles degeneration of granulosa cells, and accumulation of stidanophilic substances are-not signicantly , altered by estrogen administration. On the other hand, by administration of prehormone prior to or simultaneous with the stresses, the ovaries show almost no appreciable retardation in maturation of Graafian follicles; however accumulation of sudanohpilic substances in the stroma is marked.
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