Background: Consuming high doses of vitamin A during pregnancy may lead to malformations in the offspring. Some reports state that low doses that do not cause macroscopic abnormalities may result in mental and behavioral disorders. However, there are few studies on the microscopic effects of these doses on the organism. Objective: The aim was to investigate the effects of early prenatal exposure to different doses of oral vitamin A on the fetal liver. Materials and methods: Twenty-five pregnant rats, divided into five groups, received oral vitamin A at doses of 10,000, 50,000, 100,000, and 200,000 IU/kg between days 10 and 12 of gestation. The fetuses were collected on day 19 of gestation, their livers were dissected, and histology, apoptosis, and proliferation were examined by hematoxylin-eosin, TUNEL assay, and Ki67 immunolabeling using stereological methods. Results: Vitamin A decreased fetal liver volume, the number of Ki67-positive cells per unit volume, and the total number of hepatocytes at all doses except 10,000 IU/kg (p<0.001). Consequently, apoptosis was significantly higher in the groups receiving 100,000 and 200,000 IU/kg vitamin A (p<0.001). Conclusion: Our study shows that vitamin A administered during gestation days 10–12 has a suppressive effect on the developing rat liver when the dose exceeds 10,000 IU/kg, probably due to increased apoptosis and suppressed cell division.

Background: Vitamin A (retinol) and its derivatives are essential for maintaining cell differentiation in adult organisms as well as for normal embryonic development in fetuses. On the other hand, high amounts of vitamin A are known to be teratogenic. The formation of urogenital structures depends heavily on retinoic acid receptors. The effects of low and moderate dosages of retinol on the urinary system have not been adequately studied. The aim of our study was to investigate the effects of moderate and low doses of vitamin A on the fetal kidney. Materials and Methods: Pregnant rats were divided into 6 groups. On day 10 to 12 of pregnancy (P10-P12) the first group was administered 10000 IU/kg, the second group 20000 IU/kg, the third group 30000 IU/kg, the fourth group 40000 IU/kg and the fifth group 50000 IU/kg oral vitamin A. The control group only received 1 ml of corn oil on the same days. The fetuses were delivered via cesarean section at P19. The kidneys of the fetuses were removed after cardiac perfusion was used to fixate them. After histological preparation of the kidneys, the slides were stained with hematoxylin and eosin. By using stereological methods, the kidneys' volume (V), glomeruli per unit area (NAg), and glomeruli diameter (D) were all estimated. The results were statistically analyzed. Results: The renal volumes of the 20000, 30000 and 40000 IU/kg groups were higher than those of the other groups. It was also found that the NAg levels of the group receiving 50000 IU/kg Vitamin A were lower than those of all other groups. Moreover, the NAg levels of the groups receiving 20000, 30000 and 40000 IU/kg vitamin A were higher than those of the control group and the group receiving 10000 IU/kg. While the glomeruli diameters of the experimental groups were not different from those of the control group, the glomeruli diameters of the group receiving 20000 and 50000 IU/kg retinol were larger than those of the groups receiving 10000 and 40000 IU/kg vitamin A. Conclusions: Given the estimated higher V, Na, and D values of the group receiving 20000 IU/kg vitamin A, we can assume that this particular dose has a significant effect on renal morphology and development.

Vitamin A and its derivatives are essential for embryonic development, but an overdose of vitamin A is toxic to the offspring. The placenta is an interface that nourishes and protects the embryo. Although there are numerous publications on the effect of vitamin A on the placenta, there is insufficient information on the changes in the morphology of this organ caused by different doses. The aim of our study was to demonstrate the effect of retinyl palmitate administered at different doses on the volume of the placenta and its component, the decidua. Pregnant rats were divided into 6 groups between gestation day 10 and 12. The first group received 10.000 IU/kg, the second group 20.000 IU/kg, the third group 50.000 IU/kg, the fourth group 100.000 IU/kg and the fifth group 200.000 IU/ kg oral vitamin A. The control group received 1 ml of corn oil on the same days. On day 19 of gestation, placentas were collected and 5 µm sections were stained with Massons’s trichrome. The volumes of total placenta and decidua were estimated using the Cavalieri volume estimation method. All placental volumes of the experimental groups were larger than those of the control groups. The decidual volume increased abruptly at a dose of 50.000 IU/kg and remained higher than the control volume at higher doses. The ratio between the decidual and placental volumes increased at 50.000 IU/kg and was smaller than the control at 200.000 IU/kg. A large placental volume is thought to be an indicator of placental insufficiency. Although our results suggest that an increase in placental volume above 10.000 IU/kg may have a negative effect on placental function, we conclude that the imbalance between decidual and placental volume above 50.000 IU/kg strengthens the suggestion that placental insufficiency may have increased after this dose.

Background and Objectives: Anatomical variations in the Circle of Willis (CoW) may influence cerebral collateral pathways and the interpretation of vascular imaging. This study characterized their prevalence and clinical associations in a Turkish computed tomography angiography (CTA) cohort using complementary patient-level and component-level classifications. Materials and Methods: This retrospective, single-center study included 248 patients who underwent cranial CTA during 2024. Two radiologists independently assessed CoW anatomy, with disagreements resolved by consensus. Mutually exclusive patient-level configurations and non-exclusive arterial components were recorded. Associations with demographic and clinical characteristics were evaluated using logistic regression. Results: A normal configuration was identified in 142 patients (57.3%), and 106 (42.7%) had at least one variant. Isolated posterior communicating artery (PComA) hypoplasia/aplasia was the most frequent configuration (14.5%); PComA involvement reached 19.0% when mixed configurations were included. Isolated fetal-type posterior cerebral artery, P1 hypoplasia, and A1 hypoplasia occurred in 7.3%, 6.5%, and 4.8%, respectively. Older age (adjusted odds ratio [aOR] per 10 years, 1.57; 95% confidence interval [CI], 1.23–2.01) and migraine (aOR, 5.67; 95% CI, 2.06–15.56) were associated with variant anatomy. Previous stroke/transient ischemic attack and carotid stenosis showed inverse associations. Conclusions: CoW variants were common in this Turkish clinical cohort, particularly in the posterior circulation. Reporting both overall configurations and individual arterial components provides complementary information relevant to anatomical assessment, vascular imaging interpretation, and procedural planning.