Fill in the blank with the best possible answer.

1		The ability to combat pathogen through the activation of specific defenses is called .
2		The cells of the specific defenses are called .
3		Special lymphatic capillaries in the small intestinal villi are called .
4		The is an enlarged sac at the inferior end of the thoracic duct.
5		A collection of lymphocytes within a lymph node is called a lymphatic .
6		Antibodies attach to .
7		In order for an immune response to occur, a B or T cell must be shown an antigen by a(n) .
8		The immunoglobulin that is commonly a pentamer is .
9		The only antibody that can cross the placenta is .
10		Lymphocytes that attack infected cells are .
11		The cells that are activated B cells and produce antibodies are called .
12		Fever, species resistance, inflammation, and interferon are all part of defenses.
13		The bodies most active phagocytes are called .
14		Lymphatic vessels that enter a lymph node are called vessels.
15		Immunity is specific, reactive, versatile, and has .