Final answer:
The Endoplasmic Reticulum (ER) is the fine network of channels within cells that helps in moving substances, with roles in protein and lipid synthesis as well as material transport and storage.
Step-by-step explanation:
The fine network of channels within cells that aids in the movement of substances is known as the Endoplasmic Reticulum (ER). This network is crucial for synthesizing, transporting, and storing materials within a cell. The ER is continuous with the nuclear membrane and is composed of lipid bilayers. There are two types of ER, rough and smooth. The rough ER is associated with protein synthesis, while the smooth ER is involved in lipid synthesis and ion storage.