MICROANATOMY

Detailed explanation-1: -The homeostatic replacement of cells varies substantially among different epithelia. The epithelium of the intestine completely self-renews within ∼5 days. By contrast, interfollicular epidermis takes ∼4 weeks to renew, whereas the lung epithelium can take as long as 6 months to be replaced.

Detailed explanation-2: -Regeneration occurs in a physiologic manner in continuously dividing tissues. Sloughed-off gastrointestinal epithelial cells, for example, are replaced by new cells arising from stem cells in the intestinal crypts.

Detailed explanation-3: -Despite acting as a barrier for the organs they encase, epithelial cells turnover at some of the fastest rates in the body. Yet, epithelial cell division must be tightly linked to cell death to preserve barrier function and prevent tumour formation.