or cellular immunity, occur through the T-cell system. On exposure to an antigen, the lymphoid tissues release large numbers of activated T cells into the lymph system. These T cells pass into the general circulation. There are three main groups of T cells: (a) helper. (b) cytotoxic T cells: which attack and kill microorganisms and sometimes the body's own cells.
Organ Donation Day. About Organ Donation Day. Organ Donation Day in India is celebrated on 13th of August every year by the people, government organizations and other related professions in order to motivate normal human beings to donate the organs as well as to understand the value of organ donation in the life of an individual.
The world's third largest church organ is the Passau Cathedral Organ in Passau, Germany which has acquired the largest organ outside of the United States. It is also the largest cathedral organ in the world. The organ currently has 17,774 pipes and 233 registers, all of which can be played with the five-manual gallery console. [citation needed]