Definition of opacity for English Language Learners. : 1  the quality of a material that does not allow light to pass through it : the quality of being opaque. : 2  the quality of being difficult to understand or explain.
Research has shown that this is not true, and that brain cells can and do regenerate, especially in the areas related to learning, decision-making, visual recognition, and the way people perceive objects in space.weet. For a long time, scientists thought that it was impossible for brain cells to regenerate because they assumed that any new cells would disrupt the order of the brain.
Taste buds and olfactory receptor cells are the fastest growing and most rapidly regenerating cells in the body. Taste buds regenerate completely in a 24 hour period. The entire bud is replaced by new cells on a daily basis.lfactory epithelial cells are also among the fastest growing and regenerating cells in the body. Olfactory epithelial cells, unlike taste bud cells, regenerate in a variety of time frames, from every 24 hours to days and weeks.