general characteristics and principal functions of epithelium

what can the epithelium arise from during embryological development?

1. ectoderm (skin)

2. mesoderm (mesothelium of serous membrane)

3. endoderm (as epithelium of the intestinal tract)

what can and cannot penetrate between epithelium cells?

• blood vessels cannot penetrate between epithelial cells

  • with the exception of endocrine glands

• nerve fibers can penetrate between epithelial cells

the epithelium can do what?

it can degenerate and can rapidly regenerate

does the epithelium have a little or a lot of intracellular substance?

it has little intracellular substance, but the epithelial cells may be connected to one another by different types of cellular junctions

what does the epithelium line? what does it act as?

• epithelial tissues cover a surface or line a cavity or form a gland

• epithelial cells may act as special receptors for taste and equilibrium

what are the principal functions of the epithelium

1. protection against

   • injuries, bacteria chemicals and waters, as epithelium of skin and stomach

2. secretion as glandular epithelium of pancreas, prostate, salivary and endocrine glands

3. absorption as in the intestinal epithelium

4. sensation as the taste buds

5. reproduction as the cells of the testis and ovary

6. excretion as the cells of kidney and sweat glands

7. covering surfaces or lining cavities