Studies on the Structure of the Pulmonary Trunk

Abstract

A study of the elastic configuration of the pulmonary trunk was undertaken in 443 normal autopsy cases, ranging in ages from the second month of intrauterine life to 96 years.It has been shown that during the whole of fetal life the elastic configuration of the pulmonary trunk is similar to that observed in the ascending aorta.The "aortic" configuration of the pulmonary trunk, which is characterized by a great content of long elastic fibers, was observed in the first trimester of life, especially in the 29 days that follow birth.Two models of the "transitional" configuration have been distinguished. The "transitional-A" model is characterized by a marked fragmentation of the elastic fibers. This elastic pattern has been found between 25 days and 3 years. In the "transitional-B" model most of the fibers are partially disintegrated but not fragmented. Cases with this characteristic were found from 1 month to 9 years.The "adult" type of pulmonary configuration, which exhibits a poor content in elastic tissue, was already present in the twelfth month of life. Over the ninth year it constituted the totality of cases.A fourth elastic configuration has been added to the already known "aortic," "transitional," and "adult" types. The designation of "persistent" given to this elastic type alludes to the presence of numerous long elastic fibers that are more characteristic of the "aortic" type, alternating with others that have suffered fragmentation. Cases of the "persistent" type were found from 1 month to 5 years.A hemodynamic interpretation of the changes observed in the "transitional" models and "persistent" configuration is proposed.