Some single-celled organisms and all multicellular organisms such as humans are made up of eukaryotic cells. A eukaryotic cell always contains:
A nucleus, containing genetic material surrounded by a double envelope.
Organelles (structures) in the cytoplasm, each surrounded by one or two membranes.
Animal Cell Ultrastructure.
ultrastructure is the name for the fine structure that is revealed when using a powerful microscope such as an electron microscope.
Here are some of its organelles:
Nucleus - surrounded by a double membrane (envelope). There are pores in this nuclear envelope. There is a dark staining area , called the nucleolus within the nuclear envelope.
Centrioles - Two hollow cylinders, arranged at right angles to each other.
Lysosome - Enclosed by a single membrane and contains digestive enzymes.
Golgi apparatus - Series of single, curved sacs enclosed by a membrane. Each sac is smaller than the previous one. Many vesicles cluster around the golgi apparatus.
Mitochondria - Surrounded by a double membrane (envelope). Inner membrane folded into finger like projections , these are called cristae. Central area contains contains a jelly called the matrix. floating in the matrix are :