title: Imaging granularity of leukocytes with third harmonic generation microscopy.
abstract: Using third harmonic generation (THG) microscopy, we demonstrate that granularity differences of leukocytes can be revealed without a label. Excited by a 1230 nm femtosecond laser, THG signals were generated at a significantly higher level in neutrophils than other mononuclear cells, whereas signals in agranular lymphocytes were one order of magnitude smaller. Interestingly, the characteristic THG features can also be observed in vivo to track the newly recruited leukocytes following lipopolysaccharide (LPS) challenge. These results suggest that label-free THG imaging may provide timely tracking of leukocyte movement without disturbing the normal cellular or physiological status.
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617,  Taiwan.
authors.forename: Cheng-Kun
authors.initials: CK
authors.lastname: Tsai
authors.forename: Yu-Shing
authors.initials: YS
authors.lastname: Chen
authors.forename: Pei-Chun
authors.initials: PC
authors.lastname: Wu
authors.forename: Tsung-Yuan
authors.initials: TY
authors.lastname: Hsieh
authors.forename: Han-Wen
authors.initials: HW
authors.lastname: Liu
authors.forename: Chiou-Yueh
authors.initials: CY
authors.lastname: Yeh
authors.forename: Win-Li
authors.initials: WL
authors.lastname: Lin
authors.forename: Jean-San
authors.initials: JS
authors.lastname: Chia
authors.forename: Tzu-Ming
authors.initials: TM
authors.lastname: Liu