Morphological aspect of the thyroid ima artery in human fetuses.

Some morphological characteristics of the variable thyroid ima artery were investigated on the injected fetal arteries and explained on their 106 static images. Thyroid ima artery of different origin was proven in 18 (16.9%) cases. With respect to the vascular sources of the investigated artery, the branching of the brachiocephalic trunk and right common carotid artery was found in 72.1% of the cases. At the same time, the thyroid ima and superior or inferior thyroid arteries were obvious in all cases, as well as the presence of single or multiple variations and abnormalities of neighbouring arteries in 38.8% of the cases. No major anatomical difference was noted between the fetal form of the variable thyroid artery reported in this paper and the postnatal form reviewed from the literature. Thyroid ima artery probably represents an example of the arterial self-differentiation and induced differentiation of the unilateral vascular trunk.