five morphologic cell types were recognized in the trachea , stem bronchi , and primary bronchl : basal cells and neurosecretory cells that were basally located and did not reach the lumen and mucous cells [ mucous goblet cells and small mucous granule cells ( smgc ) ] , indifferent cells showing mucous-ciliary differentiation , and ciliated cells that reached the lumen .
C0007634
cells
C0007589
differentiation