Chloroplast. Transmission electron micrograph (TEM) of a section through a leaf mesophyll cell showing a chloroplast. Dark grey lipid drops and pale starch granules can be seen in the stroma, or matrix, of the chloroplast. The large white area of the cell is a vacuole, while the cell wall runs from bottom left to top right. The chloroplast carries out photosynthesis, producing sugars using sunlight. The part of the process that requires light occurs in the ribbon-like grana membranes. This cell is from a resurrection plant (Selaginella lepidophylla), a type of spike moss which grows in the desert. Magnification: x33,000 at 7.5x8 inch size.