General feature 1)More cells and less extracellular ground substance 2) Polarisation: free outer surface: face air or other things basal surface: face underlying CT, have basement membrane 3)Avascularity, but innervation --no blood vessels rich in nerve terminals 4)Functions protection, secretion, Absorption, excretion and sensory reception ⑧⑧昏2 General feature 1) More cells and less extracellular ground substance 2) Polarisaton: ---free outer surface: face air or other things ---basal surface: face underlying CT, have basement membrane 3) Avascularity, but innervation: ---no blood vessels ---rich in nerve terminals 4) Functions: protection, secretion, Absorption, excretion and sensory reception