Symmetric and Asymmetric Division Models
Video: Asymmetric cell division at work in the T-cell
Survival in a dirty world hinges on our capacity to eliminate hundreds of potential infections over a lifetime. To accomplish this, our bodies use a confederation of cellular and noncellular defenses. Some cells, such as the bacteria-engulfing white blood cells called neutrophils, exhibit tremendous abundance yet uniformity in the array of pathogens they can recognize. In contrast, the lymphocyte system of defense can recognize an infinite number of structures, due to a remarkable diversification mechanism that generates unique receptors on each individual lymphocyte. This, however, is at the expense of rarity in the number of each specificity. Indeed, it has been estimated that the number of naive T lymphocytes we have that are specific for any particular foreign antigen ranges between 10 and 100, a vanishing small number in an organism comprising around ...
