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The character of the estrous cycle was studied in mature rats with different variants of the experimental hypophyseal-thyroid imbalance. This state was caused by injecting rifathyroine--a synthetic analogue of thyroliberin, thyrotropin and L-thyroxin to rats having a stable 4-days estrous cycle. The above manipulations were made either in the morning hours of proestrus when a rapid growth of dominant follicles takes place in the ovary, or at the stage of diestrus when new ovarian follicles start growing. The effect of injecting rifathyroin nonspecifically stimulating the release of prolactin by the adenohypophysis was dependent on the stage of the estrous cycle in which the animal was when injecting the drug was started. If it was the proestrus, the duration and sequence of the estrous cycle phases was not changed. If injecting rifathyroin was started at diestrus, in 6 of 11 animals this stage was as long as the whole cycle period. An experimental elevation of the content of thyrotropin caused by a single injection resulted in a disturbance of the duration and sequence of phases of the estrous cycle in all the animals. If thyrotropin was injected within the first hours of proestrus, this phase became shorter and the ovulation did not take place. An injection of thyrotropin during diestrus prolonged the latter for the whole period of observations equal to the cycle duration. Injections of L-thyroxin failed to change the sequence and duration of the cycle phases practically in half of the experimental animals, independent of the phase when the injecting was started. In 6 of 11 rats given the first injection of L-thyroxin at the stage of proestrus the anestrus and a prolonged phase of diestrus (during the whole cycle) were observed afterwards.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphofunctional peculiarities of ovarian development in 1- and 4-day-old rats have been studied under conditions of their transplantation into mature female rats. In 30 days in transplants of both series of the experiments atretic process develops. Better preservation of the general pool of the germ cells and follicles is obtained at transplantation of the ovaries from the 4-day-old donors; their ovocytes at the operation time are at the stationary state of meiosis prophase. Ovocytes of 1-day-old animals, being at the stages of early prophase, are more vulnerable at homotransplantation.

Histophysiology of follicular thyreocytes of the thyroid gland of mice (line Bal) was studied under depressed function of the sympathetic nerve system (antibodies were introduced to the growth factor of the nerves). The data of electron microscopic analysis, quantitative cytochemical investigation and biochemical estimation of iodine binding with blood plasma proteins, demonstrated changes during secretory process in the follicular thyreocytes and in functional intensity of the whole gland. Stimulating effect of the sympathetic nervous system on the releasing process of the thyroid hormones is suggested.

A study was made of the effect of the sympathetic portion of the nervous system on the thyrocyte metabolism. Such morphological criteria as the volume of the thyrocyte nuclei, the amount of DNA in them and structural analysis were used. Three volumetric classes of the nuclei with a different morphological picture were detected in control animals. In depression of the sympathetic portion of the nervous system by administration of antibodies to the growth factor of the nerves there was seen a reduction of the mean nuclear volume and displacement of the volumetric classes in the direction of increase in the quantity of smaller nuclei; electron microscopic studies demonstrated changes in the shape and structure of the nuclei. There were no variations in the amount of DNA.