22]In Vivo andex Vivo tissue applications of two-photon microscopy

Abstract

Publisher Summary This chapter describes in vivo and ex vivo tissue applications of two-photon microscopy (TPM) and reviews key areas—such as neurobiology—in which TPM has already made a major impact. TPM is one of the emerging optical tissue imaging techniques, and it is constructive to compare two-photon imaging with other in vivo optical tissue imaging techniques. TPM is a powerful technique for tissue imaging because of its inherent 3D resolution and long penetration depth. This technique also provides biochemical information about tissues and causes minimal photodamage. TPM is based on a nonlinear fluorescence excitation process. The simultaneous absorption of two infrared photons promotes the transition of a fluorophore to the excited state. Because of the nonlinear excitation process, there is only sufficient photon density very near the focal region to produce appreciable excitation, which results in an inherent 3D sectioning effect. The unique advantages of TPM for deep tissue imaging have been recognized nearly since its inception. TPM tissue imaging applications are proliferating rapidly.