The animals used for this study w r were female albino rats. weighing about 150mg. these rats had.been fed with MacCollum mixture at a room temperature of 20-25°C. Various stresses such as electric shock, subcutaneous injection of 3% and 6% formalin, and exposure to 5°C were given to, them at different intervals. Alterations in the estrous.-cycles, in body weight, and in, the ovaries of the rats caused by these various stresses were observed and ´the results, obtained are as follows.
Variations in the estrous cycle;
The rats exposed to the stresses show within 5-20 days marked variations in the I estrous cycles such as prolonged, diestrous phase of the duration ranging from 6 to 10 days. A very important finding in this study is that altered estrous cycles show a tendency to return to normal. The alteration in the estrous cycle is more markedly influenced by the intensity and duration of stresses than by the varieties of them.
Variation in body weight of the rats by various kinds of stress presents no close relationship to the estrous cycle.
Alterations in the ovaries:
The weight of the ovaries of the rats given various stresses shows a 20-30% decrease compared with that of the control rats. Histologically, evidences of retardation in maturation of the Graafian follicles are noted, and only a few mature follicles can be observed.. Furthemore, degenerative changes in granulosa cells of the follicles, increased amount of sudanophilic substances in stromal tissue and well differentiated stomach cells are noticeable: These alterations in the ovaries are considered to cause the estrous cycle of the rat to become abnormal.
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