Age-related variation of lung intervascular connective tissue at different stages of postnatal histogenesis

Abstract

Aim. To study the structure of lung intervascular connective tissue at different stages of postnatal histogenesis. Methods. Lung autopsies from 20 mature males aged 22-35 years, 30 males aged 61-74 years and 30 males aged 75-89 years who died of causes unrelated to respiratory diseases were studied using standard histological techniques. Results. In lungs of young males, two separated zones of intervascular connective tissue - the central and peripheral, which differ in fiber quantity and their spatial orientation - were revealed. Collagen fibers were the main component of the extracellular matrix of lungs, accounting for 69.9% [69.5, 70.7] of matrix. The share of the base material was 30.1% [29.4, 30.5]. For older age, the share of collagen fibers increased together with decrease of the shares of elastic and reticular fibers up to the complete absence of the latter in subjects over 75 years of age. Strands of collagen fibers were strongly deformed, twisted spirally, clustered in thick bundles. Conclusion. Described age-related changes of lung intervascular connective tissue may reduce the vascular wall contractility, affecting the pulmonary circulation.