The lung in closeview: a corrosion casting study on the vascular system of human foetal trachea.

The aim of this study was to examine the tracheal vasculature in 5 month human foetuses, and to determine whether it differs from that previously described by other authors for adult human trachea. The vascular bed was visualized using the technique of corrosion casting and examined by scanning electron microscopy. The arrangement of larger vessels: longitudinal tracheo-oesophageal arteries and veins, as well as their segmental branches running circumferentially in the intercartilaginous spaces, was similar to that observed in the trachea of adults. However, no blood sinuses reported to occur in the submucous venular plexus of the human trachea could be found in the foetuses. It is postulated that the possible functions of such sinuses acting as the capacitance system are related to the functional respiratory tract; hence, this vascular specialization is not yet developed in the foetus.