The internal thoracic artery in human foetuses.

The aim of this study was to examine the internal thoracic artery (ITA) in human foetuses. The research material consisted of 32 human foetuses (18 female, 14 male) from the 21(st) to 24(th) week of intrauterine life. After intravascular injection with white latex LBS 3060, the foetuses were fixed in 10% neutral formalin solution. The whole course of the ITA was prepared. Photographic documentation was performed with a Nikon Coolpix 4500 digital camera, and source pictures of arteries were rendered in a Digital Computer System Analysis. The ITA was evaluated with regard to its origin, length, distance from the edge of the sternum to two intercostal spaces (2(nd), 5(th)) and division into terminal branches. The right ITA (RITA) arose from the ascending (68.7%), arcuate (21.9%) and descending (3.2%) parts of the subclavian artery. In other cases (6.2%) it was a branch of the thyrocervical trunk. The left ITA (LITA) was a branch of the ascending (78.1%) and arcuate (21.9%) parts of the subclavian artery. The ITA was longer in male foetuses. Regardless of sex, the LITA was longer than the RITA. Coefficient correlation between the RITA and LITA was 0.92 (p < 0.001). The distance of the ITA from the edge of sternum in the 2(nd) and 5(th) intercostal spaces on both sides was greater in females. It appeared most frequently in the 6(th) space (43.7% right-sided and 56.3% left-sided). Typical bifurcation of the ITA into the superior epigastric artery and the musculophrenic artery was observed in 78.1% of cases on the right side and in 81.25% of cases on the left side.