Sertoli cell, Coloured transmission electron micrograph (TEM) of a sertoli cell from the testis. Because its main function is to nourish the developing sperm cells through the stages of spermatogenesis, the Sertoli cell has also been called the "mother" or "nurse" cell. Sertoli cells also act as phagocytes, consuming the residual cytoplasm during spermatogenesis. The cytoplasm contains a central nucleus, mitochondria (purple), lipid droplets (brown) and agranular endoplasmic reticulum. Magnification: x3000 when printed at 10 centimetres high.