Granum
= Granum
= Grana
{synonym}
A stack of <thylakoids>.
Stacking places many <thylakoid membranes> in a compact region of a <chloroplast>. The membranes remain part of a connected internal system; the stack is a structural arrangement, whereas the <thylakoid lumen> is the enclosed aqueous compartment. <Molecular Biology of the Cell, 4th edition by Bruce Alberts and others>[Chapters 12, 18 and 19, compartments, division and cell junctions]{ref}