Tissues with high energy requirements, like cardiac muscle, are rich in mitochondria to generate sufficient ATP through cellular respiration. Cells actively synthesizing proteins require a large number of ribosomes. The nucleolus is the site of ribosomal RNA synthesis, so it would be larger and more prominent in these cells. Steroidal hormones are lipids. The Smooth Endoplasmic Reticulum (SER) is the major site of lipid and steroid synthesis. Lysosomes contain a wide range of hydrolytic enzymes capable of digesting various macromolecules and are thus the primary organelle for intracellular digestion.