1. Concept and types of tissues, epithelia
Dr Katalin Gallatz

2. Histology is the study of the microscopic structure of
biological materials
Tissues are collection of cells that freqently have
similar functions and characteristics
Human body composed of 4 basic types of tissues
epithelial tissue
connective tissue
muscular tissue
nervous tissue

3. Basic types of tissues: epithelial tissue
connective tissue
muscular tissue
nervous tissue

4. Characteristics of epithelia
1. cells of the epithelium are closely packed
2. junctional complexes between the cells
3. small amount of intercellular substance
4. cells form one or more layers
5. covers or lines all internal and external body surfaces
6. basement membrane separates it from the underlying
tissues

5. BASEMENT MEMBRANE COMPONENTS
Basal lamina produced by the epithelium (lamina lucida and lamina densa)
Fibroreticular lamina produced by the connective tissue

6. Junctional complexes 1. Cell adhesive molecules
membraneproteins (cadherins)
2. Junctional complexes
zonula occludens:
double gate, the membrans unite
zonula adherens:
15-20nm space between the membranes,
electrodens material fills it,
on the cytoplasmatic surface dark zone, made by proteins,
aktin filaments are connected to it

7. wide intercellular space
macula adherens
wide intercellular space
electrodens material fills it,
on the cytoplasmatic surface dense layer
(plaque)
intermedier filaments are embedded into it
nexus (gap junction)
is composed of menbrane channels
(connexons) ,
small molecules can pass through it

10. Cilia

11. The finger-like projections, called microvilli, increase cell surface area and
facilitate the absorption of molecules from the outside

12. Types and Functions of Epithelial Tissue
1. Covering and protection Covering epithelium
2. Diffusion
3. Absorption
4. Excretion
5. Secretion Glandular epithelium
6. Sensation Sensory epithelium
7. Contractility Myoepithel

13. 1. Covering and protection – Covering epithelium
1. epithelial cells cover the external and internal surfaces,
2. protect underlying tissue
from mechanical injury,
harmful chemicals,
invading bacteria
and from excessive loss of water.
2. Diffusion
Simple squamous epithelium promotes the diffusion of
gases, liquids and nutrients ( walls of capillaries and lungs).

14. 3.Absorption
Certain epithelial cells lining the small intestine absorb
nutrients from the digestion of food.
4.Excretion
Epithelial tissues in the kidney excrete waste products
from the body and reabsorb materials from the urine.
Sweat is also excreted from the body by epithelial cells
in the sweat glands.

15. 5.Secretion
Epithelial cells of glands are specialized for production
and secretion of materials with different chemical
characteristics

16. 6.Sensation – Sensory epithelium
Specialised epithelial tissue
found in the skin, eyes, ears, nose and on the tongue.
7.Contractility Myoepithel
in glands and
the dilator of pupil muscle

17. Types of covering epithelium
Epithelial tissue can be divided into two groups depending
on the number of layers
- simple epithelium
is only one cell thick
- stratified epithelium
is two or more cells thick

18. Simple epithelia
simple squamous
simple cuboidal
simple columnar
pseudostratified ciliated columnar

19. Simple epithelia simple squamous simple cuboidal
pseudostratified columnar
simple columnar

20. Stratified epithelia
stratified squamous non keratinised
stratified squamous keratinised
stratified cuboidal
stratified columnar
transitional epithelium

21. Simple squamous epithelium

22. Simple squamous epithelium

23. Simple cuboidal epithelium

24. simple squamous and
simple cuboidal epithelium

25. Simple columnar epithelium

26. Simple columnar epithelium
Gall bladder HE

27. Pseudostratified columnar epithelium
columnar cells
basal cell

28. Pseudostratified columnar ciliated epithelium
kinocilia
stereocilia
(long microvilli)

29. Pseudostratified columnar epithelium
kinocilia stereocilia
(regular cilia) (long microvilli)

30. Pseudostratified columnar epithelium
Epididymis, H-E,
basal cell
columnar cells

31. Pigmented epithelium

32. Types of sensory epithelium
primer secunder

33. Myoepithel
Myoepithel– specialized epithelial cells, they are able to contract,
Can be found in glands and in iris,
Contain actin, myosin, cytotokeratine

34. Thank you for your attention!