The dissertation research is dedicated to structural changes in rats’ ovaries in case of experimental precancerous conditions development, to the definition and criteria of precancerous conditions, to the hormonal treatment development with the help of gonadotropin-releasing hormone agonists (GnRH). The study contains an experimental part. Ovarian tumors development is based on the following factors: metabolic disorders (increased level of cholesterol in blood), dyshormonal disorders (hyperestrogenemia, disorders of the hypothalamic-pituitary system), disorders of compensatory mechanisms (excessive androgen aromatization (conversion) into estrogen in adipose and muscular tissues, skin; increased gonadotropic activity of the pituitary gland during menopause and puberty), immune disoders, genetic predisposition. This data confirms the necessity and advisability of studying ovarian tumors carcinogenesis and methods of its prevention and treatment. The aim of the research is the verification of the structural changes in ovaries in cases of dyshormonal disorders in the experiment according to modified Biskind’s method, to specify the criteria for precancerous conditions in rats’ ovaries, to develop a method of hormonal correction of precancerous conditions. The study was performed on 90 white outbred females rats, weight 180-200 g, which were divided into 3 groups: control group – 10, I and II experimental groups – 50 and 30 rats, accordingly. A control group of 10 animals was used to study structure of the ovaries of normal white rats. Animals from first experimental group (first stage of the study) – underwent the ovary transplantation according to modified Biskind’s method. Modified Biskind`s method consisted of transplanting one ovary to the spleen after bilateral ovariectomy. The animals of the first experimental group underwent macroscopic examination/visual-comparative analysis during laparotomy and revision of internal organs, morphological examination of ovarian tissue on the 17th, 27th, 75th, 120th, 223rd day. Blood hormones were studied on the 75th day after surgery (estradiol, progesterone, FSH, LH) using enzyme-linked immunosorbent assays by competitive enzyme-linked immunosorbent assay (ELISA). Rats from II experimental group were treated with GnRH agonist Buserelin-depo 0.15 mg: intramuscular injection was administered every month beginning from the 30th day of the postoperative period – on the 30th, 60th and 90th day for animals from II-1 subgroup. For 10 animals from II-2 subgroup injection was made on the 60th and 90th day of the postoperative period (2 injections in total). For 10 animals from II-3 subgroup the drug was administered on the 90th day of postoperative period. The animals from II group underwent macroscopic examination/visual comparison in laparotomy and revision of internal organs and morphological examination of ovarian tissue. Main factor, what influences ovary constitution at different terms after surgery, is phase of estrus cycle in the ovary at the moment of operation. When ovarian transplantation is done in the proestrus phase, we observe following structural changes in the ovary: follicle preservation on 17th day and microfollicular cysts on 75th day. Similarly, when transplantation of the ovary in metestrus or at the beginning of diestrus, we will observe thecalutein cells on the 17th day, luteal bodies on 75th day and many luteal bodies with signs of cellular atypism on the 223rd day. We demonstrated development of theca-granulosa cell tumors on 120 day after Biskind’s operation, performed differential diagnostics between Sertoli-Leydig cell tumors and theca-granulosa cell tumors using monoclonal antibodies Ingibin-alfa (DAKO, clon R1), Calretinin (DAKO, clon DAK-Calret), Melan А (DAKO, clon A103). After 223 days of graft development, we described precancerous conditions with signs of tissue (changes in the stroma/parenchyma ratio, the appearance of tissue proliferates) and cellular atypism (polymorphism of cells and nuclei, the appearance of several nuclei, changes in nuclear-cytoplasmic ratio). Hormonal correction of precancerous conditions is effective when the administration of a gonadotropin-releasing hormone agonist begins on the 30th or 60th day after surgery. This leads to decrease of FSH and LH secreation, necessary for the proliferation of structural components of the ovary, and to its atrophy. When GnRH agonist administration is started after 90 days, treatment does not affect the development of precancerous conditions in the transplanted ovary. Thus, the results of our study confirms the effectiveness of hormonal correction of precancerous conditions by intramuscular injection of gonadotropin-re leasing hormone (GnRH) agonist Buserelin-depo 0.15 mg in the experiment. Key words: precancerous conditions of the ovary, sex cord tumors, GnRH agonist, Biskind model, theca-granulosa cell tumors. Branch-Medicine.
