Mutation occurs in the tissues that receives radiations because the production of proteins by ribosomes increases. In normal conditions, ribosomes produces normal amount of protein but in this case proteins production increases by the tissue due to exposure to radioactive amino acid that causes mutation in the ribosomes and it increases its protein production.
squamous epithelium consists of a single layer of flat cells. It is found in lungs,heart and blood vessels.It allows the movement of materials across it.
stratified epithelium has many layer of flat cells.It is present in lining of oesophagus and mouth and also over the skin