Light microscopy of synaptophysin expression. (1) One-week-, (2) two-weeks-, and (3) three-weeks-old neuronal cultures immunostained for synaptophysin after (A) 1 μM acylated ghrelin ghrelin pretreatment and (B) control incubation. The reaction product appeared as dark-gray dots. Arrows point at examples of neuronal perikarya with high density of staining. Double arrows point at neurites with synaptophysin expression. Scale bars: 20 μm.