Epithelial tissue and it's type

1. Epithelial Tissues
Good fences make good
neighbors

2. Epithelial Tissues
 Cover ALL body surfaces, line organs, are
major tissues of glands
 1 side is exposed to open space,
underside is attached to connective tissue
by a thin, non-cellular basement
membrane
 Lack blood vessels, fed by diffusion from
well vascularized connective tissues

3. More Epithelial Characteristics
 Reproduce rapidly
 Tightly packed
 Good barriers: Skin, lining of mouth
 Involved in secretion, absorption,
excretion, sensory reception

4. Simple Squamous Epithelium
 1 layer, thin, flattened
 Broad, thin nucleus
 Things pass through these easily:
diffusion, filtration
 Easily damaged
 Found in: Alveoli, capillary walls, blood,
lymph vessel lining, body cavity lining

5. Simple Squamous Epithelium

6. Simple Squamous Epithelium

7. Simple Cuboidal Epithelium
 1 layer, cube shaped cells
 Central, spherical nucleus
 Covers ovaries, kidney tubules, glandular
ducts (salivary, thyroid, pancreas, liver)
 Secretion (in glands)
 Absorption (kidneys)

8. Simple Cuboidal Epithelium

9. Simple Cuboidal Epithelium

10. Simple Columnar Epithelium
 Elongated, 1 layer
 Nuclei located near basement membrane
on about the same level
 Line uterus, most organs of digestive tract
 Thick, protective of underlying structures
 Secretes digestive fluids, absorbs
nutrients
 Can have microvilli
 Can have goblet cells embedded, secrete
mucus onto surface

11. Simple Columnar Epithelium

12. Simple Columnar Epithelium

13. Pseudostratified Columnar
Epithelium
 Appear layered, but not: Nuclei stacked at
different levels
 Often found with cilia, goblet cells
scattered throughout
 Lines respiratory, reproductive systems

14. Pseudostratified Columnar
Epithelium

15. Stratified Squamous Epithelium
 Thick, composed of several layers
 Cell division at deeper layers, older cells get
pushed up/out
 In epidermis, lines mouth, throat, vagina,
anus
 In epidermis, keratin (a tough protein)
causes old cells to harden and die, forming
a protective layer.
 Keritinization causes cells to become tough,
dry
 This keeps water in, chemicals, microbes
out

16. Stratified Squamous Epithelium

17. Stratified Cuboidal Epithelium
 Have 2-3 layers which line a lumen
 Line larger ducts like in mammary glands,
sweat glands, salivary glands, pancreas
 Also found lining ovarian follicles,
seminiferous tubules

18. Stratified Cuboidal Epithelium

19. Stratified Columnar Epithelium
 Layers of cells
 Superficial (shallow) cells are elongated,
deeper cells (basal layers) are cuboidal
 Found in male urethra, vas deferens, parts
of pharynx

20. Stratified Columnar Epithelium

21. Stratified Columnar Epithelium vs
Stratified Cuboidal Epithelium

22. Transitional Epithelium
 Changes in response to tension: stretchy
 Inner lining of bladder, lining of urinary
passages
 Several layers of cuboidal cells
 Flatten when stretched, cuboidal when
relaxed
 Keeps urine in

23. Transitional Epithelium

24. Transitional Epithelium

25. Glandular Epithelium
 Specialized to make and secrete a product
 Found mostly within cuboidal and columnar
epithelia
 Exocrine glands secrete into ducts.
 Merocrine glands: watery, protein-rich secretions
 Serous Cells: secretions are watery, enzyme filled (serous
fluid): found in glands in body cavities
 Mucous cells: secrete thick mucous containing mucin, a
glycoprotein: In digestive, respiratory systems
 Holocrine Glands: cell bursts during secretion
 Apocrine glands: cell loses some cytoplasm during
secretion
 Endocrine glands secrete into blood

26. Glandular Epithelium