FETAL ANATOMICAL VARIABILITY OF THE THYROIDS VEINS AND UNPAIRED THYROID PLEXUS

The thyroid gland is called the fi violin in the orchestra of endocrine glands due to its high hierarchical position. It regulates primary metabolism and energy and significantly influences other endocrine organs. Therefore, our study aimed to establish the fetal anatomical variability of the thyroid veins and unpaired thyroid plexus. Material and methods. Using the methods of macromicroscopic preparation under a falling drop of water and injection of venous vessels, the topographic and anatomical features of the thyroid veins and unpaired thyroid plexus were investigated on 17 preparations of human fetuses of 4-10 months (81.0-375.0 mm parietal- coccygeal length (PCL)). Violations of moral and legal norms during medical and scientific research were not detected. Results. In most studied fetuses, the upper thyroid vein began with two trunks and accompanied the artery of the same name. Near the lower edge of the thyroid glands isthmus is an unpaired thyroid plexus, the formation of which involves 3-5 veins that connect into venous trunks of a larger diameter or anastomose with each other. In 7 fetuses, one lower thyroid vein started from the unpaired thyroid plexus; in 6 cases – two veins and four observations (fetuses 185.0, 190.0, 220.0, and 320.0 mm PCL) – 3-4 lower thyroid veins. In our study, the places of the confl of the lower thyroid veins were: in 4 fetuses – the left brachiocephalic vein; in 2 observations – the confluence angle of the right and left brachiocephalic veins; and in one fetus – the right brachiocephalic vein. In 11 fetuses, the lower thyroid veins were in front of the brachiocephalic trunk. In 6 of them, the lower thyroid veins crossed the brachiocephalic trunk above the jugular notch of the sternum and, in 5 cases – behind the sternum. In 6 observations, the lower thyroid veins had no close topographical-anatomical relationship with the brachiocephalic trunk. Conclusions. Anatomical variability of the superior, middle, and inferior thyroid veins has been established in human fetuses. The structure of the unpaired thyroid plexus, the number of lower thyroid veins, and the places of their confluence are variable.