[Morphologic particulars in the peripheral pulmonary artery of the lungs in neonates (author's transl)].

Morphological particulars in small branches of the pulmonary artery in newborn children are described: small diameter; hypercellular intima; thick media; wide adventitia, consisting of connective tissue only; epitheloid cells between intima and media as well as media and adventitia. "Sperrarterien" are also seen. These structural changes in the small branches of pulmonary artery, the reduction of the hypertrophic wall of the right ventricle, and the increase of the magnitude of respiration--processes during the first 4 months of life--are considered important factors in explaining the frequency of sudden infant death during the first 4 months of life.