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.
Photograph of HE-stained lung tissue under an optical microscope (×200). M1, 2-week cigarette smoke (CS) exposure group; M2, 4-week CS exposure group; M3, 8-week CS exposure group; M4, 12-week CS exposure group; M5, 8-week CS exposure + 4-week CS cessation group; M6, 24-week CS exposure group; M7, 36-week CS exposure group; N1, 12-week normal group; N2, 24-week normal group; N2, 36-week normal group. H&E, haematoxylin–eosin.
