Differential uptake and transport of fluorescent probes β-Bodipy C5-HPC, Bodipy FL C5 Ceramide and Bodipy 505/515: Widefield and confocal fluorescence microscopy. (A – C) β-Bodipy C5 ceramide uptake and distribution: the ceramide fluorophore (green) exhibited properties consistent with passive diffusion across cell membranes, with distinct uptake over the gill (GL) and transport through the cardiovascular system. The fluorophore was not observed to cross the blood-brain barrier (C), though it persisted in vasculature, with a residence time of hours to days (depending on exposure regime). (D) In contrast, β-Bodipy C5 phosphocholine (HPC) was observed to label neurons in the hind brain of STII medaka. Frame D is a confocal fluorescence image (from 3D projection) of β-Bodipy C5 phosphocholine labeling neural bundles in the corpus cerebelli, crista cerebellaris and medulla, 90 minutes post fluorophore exposure (aqueous bath) (STII medaka, 18 dpf). Corpus cerebelli, crista cerebellaris and medulla are region of interest indicated by gray rectangle in frame (C). (E1 and E2) Widefield fluorescence microscopy of Bodipy 505/515 secretion (red fluorescence) from gall bladder (GB) through the cystic duct (CD) and common bile duct (CBD) into the gut lumen. Mucosol folds of the gut (Mf) are the result of β-Bodipy C5 ceramide fluorescence (co-administered with Bodipy 505/515). Ventral aorta (Va), Heart Ventricle (Hv), Heart Atrium (Ha), Liver (L), Pineal Gland (P), Optic Tectum (Ot), Otic Vesicle (Ov), Vasculature (V).