Abdulkadir Bilir; Emre Atay; Fatma Firat; Ayse Ertekin & Erhan Bozkurt

Letrozole is mainly used for the treatment of unexplained infertility, breast cancer and polycystic ovarian syndrome, with secondary use in ovarian stimulation. In cases of unexpected or unknown pregnancy during the use of letrozole, letrozole may cause a teratogenic effect on the fetus. In this reason, in this study, we aimed to determine the effect of letrozole on fetal bone development. In this study, 32 pregnant Wistar albino rats were used. The rats were divided into four groups: Control (saline) and high; 0.3 mg/kg, medium; 0.03 mg/kg, low; 0.003 mg/ kg letrozole. Saline and letrozole were administered in 100 mL solutions by intraperitonaly from day 11 to day 15 of pregnancy. The skeletal system development of fetuses was examined with double skeletal staining, immunohistochemical staining methods and mineral density scanning electron microscopy. A total of 100 fetuses from female rats, 25 in each group, were included in the study. As a result of that, ossification rates were observed to decrease depending on the dose of letrozole in the forelimb limb (scapula, humerus, radius, ulna) and hindlimb (femur, tibia, fibula) limb bones. As a result of the statistical analysis, a statistically significant decrease was found in the ossification rates of all bones between the control group and low, medium, high letrozole groups (p<0.001). Exposure to letrozole during pregnancy adversely affected ossification and bone growth. However, the teratogenic effects of letrozole are unclear. Therefore, it needs to be investigated more extensively.

KEY WORDS: Double skeleton staining method; Letrozole; Ossification.

BILIR, A; ATAY, E.; FIRAT, F.; ERTEKIN, A. & BOZKURT, E. Investigation of teratogenic effects of letrozole on fetal bone development. Int. J. Morphol., 40(4):1108-1116, 2022.