Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
The mucus protective system of normal upper respiratory tract of higher animals. (a) Submucosal glands generate mucus bundles by >1000 MUC5B mucin linear polymers. The bundles are moved by the cilia and the air surface liquid (ASL). The mucus bundles are coated by the MUC5AC mucin from the surface goblet cells. (b) Mucus bundles stained with Alcian blue are moved cephalically over the tracheobronchial surface.
