<prompt> The short term effects of radiation on a tissue are determined by the sensitivity of its:Mesenchymal cellsEctodermal cellsParenchymal cellsNone of the above  <response>: The short-term effects of radiation on a tissue effects seen in the first days or weeks after exposure are determined primarily by the sensitivity of its parenchymal cells.White and Pharoahs Oral Radiology Principles and Interpretation,7th edition 