Tattoo needle puncture in skin, coloured scanning electron micrograph (SEM). Skin tattooing has been practised for thousands of years. To make tattooing permanent, tiny needles are used to punch through the top layer (epidermis) of the skin and into the next layer (dermis). This image shows many flat human skin cells, some damaged, from the epidermis surrounding a hole created by a tattoo needle. Magnification: x250 when printed at 10cm wide.