Preliminary trial of identification of brain structures in nude mice with green fluorescent protein expression by fluoroscope

Objective To explore the feasibility and advantage of fluoroscope in identification of brain structures in nude mice with green fluorescent protein (GFP) expression. Methods We laid the whole brain separated from 8-week adult nude mice with GFP expression into SLY mouse brain blocker to produce slices of 1 or 0.9 mm thickness; and then,25 μm-thickness frozen sections were cut.Fluoroscope was employed to observe the morphological structure to define their anatomic structures with reference to The Mouse Brain in Stereotaxic Coordinates compiled by Paxinos. After the observation,these frozen sections were performed Nissi staining for contrast. Results Different structures can be identified by their distinct fluorescence intensity:the dense areas of nuclei,Nissl bodies and nerve tract showed low fluorescence intensity; while the structures around the areas of nuclei and nerve tract,such as,the plexiform layer of olfactory bulb and the molecular layer of cerebella,showed high fluorescence intensity.The fluorescence intensity was attenuated obviously after Nissl staining; the visualized structural information observed under stereomicroscope was in accordance with that viewed by fluoroscope.Conclusion The identification of brain structure in nude mice with GFP by fluoroscope can serve as an experimental platform being applied in the anatomic structure positioning in fluorescence tracer experiments. Key words: Green fluorescent protein;  Mouse;  Brain;  Anatomic structure localization without staining