Image of the Week: Stem Autofluorescence Autofluorescence image of an avocado (Persea americana) stem cross-section. The intrinsic fluorescence highlights the structural organization of vascular tissues, with xylem vessels and surrounding cell walls clearly delineated in bright green. Autofluorescence signal arises primarily from lignin and phenolic compounds in secondary cell walls. [2025 #OPNPhotoContest ] Maria Alice Paularie (LabNS, UFMG), Élder Paiva (PlantSeR, UFMG), Leandro M. Malard (LabNS, UFMG), Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil *Link in Bio