The alveolar pores of Kohn in young postnatal rat lungs and their relation with type II pneumocytes

Abstract

In order to obtain more information on the development, morphology and function of the pores of Kohn, the lungs of Wistar rats are studied during their early postnatal period, up to 3 weeks of age, by scanning and transmission electron microscopy. The substantial development of the interalveolar pores on days 14 and 21 coincides with the period of septal rearrangement when secondary interalveolar septa become lengthened and thinner. The high frequency of transseptal type 11 pneumocytes from day 7 onwards, and their typical localization near the pores of Kohn at this period of lung development especially suggests that type 11 pneumocytes are engaged in the formation of the pores of Kohn. During early lung development, the pores of Kohn seem to serve as passageways for alveolar macrophages.