Why are epithelial membranes thin?
a. epithelial tissues cannot support other cells growing on top of the tissue
b. epithelial tissues are not able to grow past several layers because of an interrupted cell cycle which occurs after several complete cell cycles.
c. epithelial tissues can only reach a certain level of thickness because of their pre-programmed cell growth.
d. epithelial tissues are nourished by blood vessels in adjacent tissues, thus diffusion is limited to thin tissues.
e. epithelilal tissues that are much greater than a few cell layers in thickness collapse because of drying conditions caused by the environment.