Lipids form multiple intracellular droplets in the ‘lactating’ crop. A fluorescent Oil Red O stain visualised by confocal microscopy reveals the location of neutral lipid in the ‘lactating’ pigeon crop. (A) Neutral lipid (red) is present throughout the differentiated epithelium of the ‘lactating’ pigeon crop. Scale bar = 60 μm. (B) Lipid droplets are perinuclear (nucleus stained blue, DAPI). Scale bar = 10 μm.