Fig. Upper: Dendritic spine of a Purkinje cell gradually denuded from its axon terminal (green), astrocytic sheath (blue), synapse (red), and finally made transparent to show its smooth endoplasmic reticulum. (Mouse, cerebellar cortex.) Scale = 0.5 µm. Download the high resolution image.

Lower: Mushroom-shaped dendritic spine of hippocampal stratum radiatum possessing a perforated synapse with its nascent (magenta) and active (red) zones and a spine apparatus (yellow). The 3D architecture of endoplasmic reticulum of both dendritic spines looks similar, but that of the mushroom spine is always associated with the perforated synapse and contains dense plates between its cisternae (cf Fig. (Mouse, cerebellar cortex. Rat, hippocampus.) Scale = 0.5 µm.