1. Single-celled green alga: nucleus, nucleolus, chloroplast, mitochondria, starch granules, vacuoles, ribosomes, bases of two flagella. TEM.

2. Rat liver cell: nucleus, nucleolus, nuclear envelope, mitochondria, rough endoplasmic reticulum, Golgi apparatus. TEM.

3. Section through a HeLa cell at mid-cleavage. TEM.

4. Ciliate Paramecium caudatum: green macronucleus, smaller micronucleus, contractile vacuoles. LM, fluorescent stain.

5. Freeze-fractured, etched green alga: nuclear membranes with pores, Golgi apparatus, vacuole, portions of chloroplast. TEM.

6. Freeze-fractured protist cell: surface of nucleus, numerous circular pores, two Golgi apparatus. TEM.

7. Parenchyma cell from spinach: nucleus (bright yellow), nucleolus within (even brighter). Fluorescent LM.

8. Cell of a plant stamen hair: nucleus, vacuole, and cytoplasmic strands.

9. Nucleus of a rat hepatocyte: nucleolus, double-membraned nuclear envelope, pores. TEM.

10. Nucleus in a monkey liver cell: chromatin (scattered dark material) and nucleolus (round, dark region). TEM.

11. Plant parenchyma cell: nucleus, nuclear envelope, vacuoles, chloroplasts, mitochondria, Golgi apparatus, plasma membrane, cell wall. TEM.

12. Metaphase spindle of a cultured cell: kinetochore microtubules, centromeres, sister chromatids. High-voltage TEM.