The problem of male infertility is relevant and calls for a solution. The use of the D3 vitamin in infertility treatment schemes has a potentially positive effect on reproductive health in male individuals. The present study aims to examine the effect of vitamin D3, administered alone or in combination with a preparation containing the extract of Tribulus terrestris on the changes in the histological picture of testicular morphology in rats with experimental gonadopathy. Male rats with modeled reproductive function pathology (Serotonin-induced gonadopathy) were divided into groups receiving correction using cholecalciferol alone or in combination with the reference drug Tribestan (Tr), which contains an extract of Tribulus terrestris. In addition to observational microscopy, morphometric evaluation of spermatogenesis was performed on sections of the testicles stained with hematoxylin and eosin. The statistical analysis was performed using the standard software package “Statistica 6.0” with the utilization of the Student’s t-test and its nonparametric counterpart, the Kruskal-Wallis test for one-way analysis of variance, followed by the Mann-Whitney test. It was found that the seminiferous tubules of rats with Serotonin-induced gonadopathy are significantly reduced in size, and their tunica propria is thickened. Sertoli cells are often destructively altered, and the uniformity of their arrangement is disrupted. A decrease in the weight of the gonads, epididymis, prostate gland, and hypoandrogenization was observed as well as a decline in spermatogenesis indicators. An improvement in the morphological characteristics of the gonads was noted following the administration of vitamin D3 in the presence of pathology. The seminiferous tubules had a normal histological structure. The germ cells were arranged in concentric rows according to their developmental stages, and the Sertoli cells appeared visually unchanged. The population of Leydig cells appeared visually more heterogeneous than in the control animals. However, occasionally seminiferous tubules with focal necrobiosis of germ cells and dystrophy of Sertoli cells, as well as a reduction in rows of germ cells, were observed. Overall, the quantitative indicators of spermatogenesis improved after the administration of vitamin D3 compared to rats with experimental gonadopathy, although they did not reach the levels of the intact control. The administration of a combination of vitamin D3 and Tribestan in the presence of gonadopathy resulted in a greater positive effect compared to their individual use. The microscopic condition of the testicular tissue in rats was fully recovered. The combined use of vitamin D3 with Tribestan normalized the weight of the gonads and their appendages, significantly reduced the manifestations in the histological sections of degeneration and damage in the reproductive cells during the period of growth and differentiation, improved the relative level of androgen status in the organism and had a positive effect on spermatogenesis in the gonads. Thus, we have established that the combined use of Сholecalciferol and Tribestan for correcting experimental gonadopathy was more effective than either of the mentioned components alone.

One of the current problems is the study of the effects of vitamin D on the body, and in men its action is closely related to the pathogenesis of androgen deficiency and hypofertility. Particular attention needs to be paid to determining whether cholecalciferol (D3) has a negative effect on the gonads and spermatogenesis of intact individuals, as vitamin D therapy is used in reproductive disorders with or without vitamin D deficiency. The aim of the study was to determine the effect of vitamin D on the histological structure of gonads and morphometric parameters of spermatogenesis of adult intact male rats. The studies were performed on adult sexually active male Wistar rats. Vitamin D3 was administered orally in doses of 1000 IU, 4000 IU and 10000 IU. The solutions were made on seed oil. The control was intact rats. Vitamin D and its solvent were administered throughout the period of spermatogenesis and the time of maturation of sperm in the epididymis, after which the structural organization of the testes was determined. Gonadal samples were fixed in 10 % formalin solution, leave in alcohols of increasing strength, and embedded in paraffin. In addition to survey microscopy, morphometric evaluation of the process of spermatogenesis was performed on sections of gonads stained with hematoxylin and eosin. Micropreparations were examined using a Granum L 30 (03) light microscope, and microscopic images were taken with a Granum DSM 310 digital video camera. Photographs were processed on a Pentium 2.4 GHz computer using Toup View. Statistical processing of data results was performed in the standard software package "Statistica 6.0" using Student's t-test and using a non-parametric analogue of one-way analysis of variance – Kruskal-Wallis criterion. In rat testicular sections, seminiferous tubules were located transversely or obliquely and were oval or round in shape. The diameter of the tubules is normal, the tubular membrane, as well as the protein and vascular membranes were normal. The basal department contains the youngest cells of the germinal epithelium – spermatogonia. Cells have a pronounced functional activity. Morphometric characteristics of spermatogenesis of intact rats corresponded to the physiological norm. The introduction of the solvent throughout the period of spermatogenesis and maturation of mature sperm in the epididymis did not affect the histoarchitectonics of the testicles. The testicular lobes are filled with concentric or flattened profiles of sections of the seminal tubules, which are close enough to each other. The diameter of the tubules is normal, the intrinsic membrane of the tubules, as well as the protein and vascular membranes corresponded to those in intact animals. 3-4 generations of spermatogenic cells, which were at different stages of development, can be seen in the tubules. However, few tubules with focal destruction of the germinal epithelium and exfoliation of germ cells in the lumen of the tubules have been observed. No significant changes in the microstructure of the seminal tubules were observed after administration of vitamin D at all doses studied. Not only spermatogenesis but also spermiogenesis is clearly traced in different tubules of rats – stages of cellular transformations from spermatid to sperm. Morphometric parameters of the process of spermatogenesis of rats receiving different doses of vitamin D3 do not differ from those of intact rats. Thus, the use of vitamin D in these doses revealed the safety of its effect on the number of spermatogonia and tubules with stage 12 meiosis. When cholecaciferol was used in male rats for 68 days, the spermatogenesis index remained at the level of animals that did not receive the test substance. The use of vitamin D3 in intact adult male rats does not adversely affect the histological structure of the testes.