THE LAND: Afghanistan is known for it's mountainous terrain. The huge Hindu Kush mountains form a barrier between the Northern provinces and the rest of the country. This mountain range has also divided Afghanistan int three very different geographic regions known as; The Central Highlands, The Northern Plains, and the Southwestern Plateau.
â Antibody producing B cells develop into plasma cells â¢ Plasma cells only found in lymphoid organs, not in general circulation or lymph â¢ eccentric nuclei and perinuclear halo (clear region under nucleus) â Clonal expansion leads to development of effector cells or memory cells for both T and B events. Memory cells can survive 20 years or
Because of these rearrangements, each of the approximately 1012 B cells and 1012 T cells in a human being has a different receptor on its surface. These B and T cells exist within the blood and lymphatic system of the body in what is called a resting state--that is, they are not doing anything detectable. However, when a B or T cell encounters an invader that can bind to its receptor, the cell divides many times and so creates lots of daughter cells.