There are five classes of antibody.
1) IgA (immunoglobin A)
2) IgD (immunoglobin D)
3) IgE (immunoglobin E)
4) IgG (immunoglobin G)
5) IgM (immunoglobin M)
They form Y shaped antibodies. The crystallized fragment is the stalk of the Y shaped antibodies. The bond formed by this stalk will determine the form of the antibody. One Y is called monomer, two connected Ys are called dimers, and 5 connected Ys are called pentamers.
