Color enhanced Transmission Electron Micrograph (TEM) section of Pyrenoid: Region of dense stroma (green) projecting from the main body of the chloroplast (also green) in the euglenoid Colacium: pyrenoids occur only in some phytoflagellates, algae and liverworts, and are concerned with the production of reserve carbohydrates from the primary products of photosynthesis; in euglenoids, the reserve is not starch but paramylon; a membrane limited cap of paramylon is seen external to the 3-membraned chloroplast envelope; closely associated with the pyrenoid; within the pyrenoid matrix the photosynthetic lamellae are composed of only two thylakoids, elsewhere in the chloroplast the lamellae have three or more thylakoids; pyrenoids may be projecting from or embedded in the chloroplasta; the surrounding cytoplasm contains mitochondria (blue) a Goldgi body (red) and ribosomes. Magnification: 20,000x.