three epithelial cell types were recognized : principal cells , gland cells and endocrine cells , making up about 65 % , 15 % and 1 % , respectively , of all cells present , while approximately 20 % of the cells in the epithelium are lymphocytes , 1 % appear to be discharged gland cells , and 2 % degenerating cells .
C0014597
epithelial cell types
C0014609
epithelium