Model of a typical animal cell. In the middle is the nucleus (blue, dimpled), inside of which is the nucleolus surrounded by chromatin fibres (red). Surrounding the nucleus is rough endoplasmic reticulum (red), with smooth endoplastic reticulum at lower right (yellow spots). At bottom centre is the Golgi complex (yellow). Also present are mitochondria (red, peanut-shaped) and lysozymes (green spheres). At upper left are centrioles (yellow, ridged).