Dictyosomes of higher plant cells have usually four to eight cisterns stacked together. These sacs do normally branch into series of tubules and free vesicles at their margins. The Golgi apparatus is an important coordination point of the cell's vesicular flow and of its molecular export. Organelles Organelles are membrane-surrounded functional unities of the cell. Mitochondria, the sites of respiration, and plastids, of which chloroplasts are the most striking members are maybe their best-known representatives.
Mitochondria occur both in animal and plant cells, plastids only in the latter.
Mitochondria consist of two membranes , the inner and the outer membrane, who form no continuous system. The inner membrane is strongly folded with the folds expanding into the inner of the mitochondrion, the matrix . The plastids contain three different types of membrane. The inner and the outer membranes of the plastids form the plastid's envelope. Within this envelope lies with chloroplasts the thylakoid system that can be recognized in fully developed chloroplasts by a specific folding pattern .