Demonstration of lung type II cell differentiation by polarized light microscopy.

Birefringence is shown to be a property of lamellar bodies in living lung type II cells and is used to demonstrate the appearance of differentiated type II cells in cultures of fetal rat lung explanted as early as Day 13. The culture medium was F-12 K without added serum, hormones, or growth factors. This system is considered to be potentially useful in analyzing factors and cell interactions involved in determination and cytodifferentiation of the type II cell from lung bud epithelium.