Epithelia l t issues I IEpithelia l t issues I I ..

Strat ified squam ous nonkerat inized Strat ified squam ous nonkerat inized epitheliumepithelium

Strat ified squam ous kerat inized Strat ified squam ous kerat inized epitheliumepithelium

Strat ified colum nar epitheliumStrat ified colum nar epithelium

Transit ional epitheliumTransit ional epithelium

Unicellular glandUnicellular gland

Exocrine glandExocrine gland

Stratified squamous nonkeratinized Stratified squamous nonkeratinized epitheliumepithelium 1.:1.:

I ts cells form I ts cells form threethree layers:layers:1.1. St ratum Stratum

germ inat ivum / basale/ cylindrocellularegerm inat ivum / basale/ cylindrocellulareConsists of a single Consists of a single rowrow of columnar cells of columnar cells resting on the basal lamina.resting on the basal lamina.The intense mitotic activity is responsible for The intense mitotic activity is responsible for the replacement of the removed cells from the the replacement of the removed cells from the surface.surface.The junction of the epithelium and connective The junction of the epithelium and connective tissue is irregular, the interdigitations of tissue is irregular, the interdigitations of connective tissue called papillae between connective tissue called papillae between evagination of the epithelium enhance the evagination of the epithelium enhance the adhadheesion of the two sion of the two tissuetissue typestypes..

2.2. Stratum spinosum:Stratum spinosum:Consists of polygonal cells bound together by Consists of polygonal cells bound together by desmosomes.desmosomes.As a consequence of tissue preparation, the cells decrease As a consequence of tissue preparation, the cells decrease in size and remain bound by desmosomes located at the in size and remain bound by desmosomes located at the tips of spiny cellular projections; the name of this layer is tips of spiny cellular projections; the name of this layer is suggestive for this spinesuggestive for this spine--studded appearancestudded appearance

3.3. Stratum planocellulare:Stratum planocellulare:Flattened cells that retain their nuclei.Flattened cells that retain their nuclei.

Location:Location:Oral cavity, esophOral cavity, esophaagusgusVaginaVaginaThe corneal epitheliumThe corneal epithelium

Str. planocellulare

Str. spinosum

Str. germinativum

lumen

epithelium

Layers:Layers:11 .Stratum basale (germinativum):.Stratum basale (germinativum):

Form ed by colum nar cells present ing intense m itot ic Form ed by colum nar cells present ing intense m itot ic activityactivity

2.2.Stratum spinosum:Stratum spinosum:Polygonal cells are alike those of the nonkerat inized Polygonal cells are alike those of the nonkerat inized epithelium.epithelium.

3.3.Stratum granulosum:Stratum granulosum:Consists of flat tened cells w ith basophilic keratohyalin Consists of flat tened cells w ith basophilic keratohyalin granules.granules.

4.4.Stratum lucidum:Stratum lucidum:Translucent , thin layer of eosinophilic cells lacking nuclei.Translucent , thin layer of eosinophilic cells lacking nuclei.

5.5.Stratum corneum: Stratum corneum: Keratinized nonnucleated cells, horny cells, that are Keratinized nonnucleated cells, horny cells, that are continuously shed at the surface.continuously shed at the surface.

Location: the epidermis of the skinLocation: the epidermis of the skin

epithelium

Str. corneum

Str. lucidum

Str. granulosum

Str. spinosum

Str. germinativum

Dermis

Hypodermis

Stratified cuboidal epithelium: present in the duct Stratified cuboidal epithelium: present in the duct of the sweat glandof the sweat gland..

Urothelium/ transitional epithelium:Urothelium/ transitional epithelium:Layers:Layers:1. Columnar cell layer1. Columnar cell layer2. Polygonal cells2. Polygonal cells/ / pearpear--shapedshaped cellscells3. Domelike facet cells3. Domelike facet cells, , alsoalso calledcalled umbrellaumbrella cellscellsLocation:Location:

Renal pelvisRenal pelvisUrinary bladderUrinary bladderUpper part of the urethraUpper part of the urethra

Lumen

epithelium

Umbrella cells

Columnar cells

Polygonal cells

The superficial layer consists of columnar The superficial layer consists of columnar cells, while cuboidal or smaller columnar cells, while cuboidal or smaller columnar cells are present in the basal layer.cells are present in the basal layer.

Location:Location:The bulbous part of the male urethraThe bulbous part of the male urethraCConjunctivaonjunctivaInterlobularInterlobular excretoryexcretory dducts of glandsucts of glands

Lumen

Columnar cell layer

I t is form ed by cells specialized to I t is form ed by cells specialized to produce a fluid secret ion.produce a fluid secret ion.Types of glandular epithelia:Types of glandular epithelia:

Endocrine Endocrine glandsglands: d: ductless glads, their uctless glads, their secretion is picked up and transported by the secretion is picked up and transported by the bloodstream, or diffuses into the surrounding bloodstream, or diffuses into the surrounding extracellular fluid and acts on the neighbouring extracellular fluid and acts on the neighbouring target cells (paracrine effect). Their secretions target cells (paracrine effect). Their secretions are called hormones.are called hormones.ExocrineExocrine glandglandss: u: usually present ducts sually present ducts through which the secretory product passes to through which the secretory product passes to reach the surface.reach the surface.

General st ructure of the exocrine gland:General st ructure of the exocrine gland:Secretory portion (acinus)Secretory portion (acinus): its shape may be acinar, tubular, : its shape may be acinar, tubular, tubuloacinar.tubuloacinar.DuctDuct: it is unbranched in simple glands, and repeatedly branched in : it is unbranched in simple glands, and repeatedly branched in compound glands.compound glands.

Classificat ion of the exocrine glands according to their Classificat ion of the exocrine glands according to their positionposition: endoepithelial, exoepithelial.: endoepithelial, exoepithelial.

Classificat ion of the exocrine glands according to the Classificat ion of the exocrine glands according to the chemical nature of the secretion:chemical nature of the secretion:

Serous glandsSerous glands: tight lumen, secretory cells with basophilic cytoplasm : tight lumen, secretory cells with basophilic cytoplasm and round nucleiand round nucleiMucinous glandsMucinous glands: large lumen, the flattened cell nuclei are situated in : large lumen, the flattened cell nuclei are situated in the basal portion of the cell. The cells appear clear in HE staithe basal portion of the cell. The cells appear clear in HE staining ning because of the mucin garnules.because of the mucin garnules.Demilunes of GianuzziDemilunes of Gianuzzi:: serous cells are attached to the mucinous serous cells are attached to the mucinous secretory portion, forming serous demilunes.secretory portion, forming serous demilunes.

Classificat ion of the exocrine glands according Classificat ion of the exocrine glands according to the m echanism of secret ion:to the m echanism of secret ion:Merocrine mechanismMerocrine mechanism: the secretion product is : the secretion product is present in granules sorrounded by membranes, present in granules sorrounded by membranes, and it is released by exocitosis. E.g.: salivary and it is released by exocitosis. E.g.: salivary glands.glands.Apocrine mechanismApocrine mechanism: the secretion is eliminated : the secretion is eliminated together with the apical portion of the cytoplasm. together with the apical portion of the cytoplasm. E.g.: release of the lipid component of the E.g.: release of the lipid component of the secretion in lactating mammary gland.secretion in lactating mammary gland.Holocrine mechanismHolocrine mechanism: the entire secretory cell : the entire secretory cell tranforms in secretion. E.g.: sebaceous gland. tranforms in secretion. E.g.: sebaceous gland.

PAS-positive mucin droplets

PAS-positive brush border

Intestinal lumenIntestinal villus

Mucinous acini

Serous acini

Ductus salivaris

Demilune of Gianuzzi

Receives external stimuliReceives external stimuliIt is composed of modified It is composed of modified epithelial cells, which epithelial cells, which represent a transition represent a transition between epithelial and nerve between epithelial and nerve cells.cells.

Classification of the cells of the Classification of the cells of the neuroepithelium:neuroepithelium:Primary sensory cell Primary sensory cell (neuroepithel cell): presents (neuroepithel cell): presents process. E.g.: cells of the process. E.g.: cells of the olfactory epitheliumolfactory epitheliumSecondary sensory cell Secondary sensory cell (neuroepithel cell): does not (neuroepithel cell): does not present processes, stimuli present processes, stimuli pass on neural ganglia. E.g.: pass on neural ganglia. E.g.: taste buds, hair cells of the taste buds, hair cells of the internal earinternal ear

Hair cells in the organ of Corti

It is composed of It is composed of cells that contain cells that contain granules of melanin. granules of melanin. E.g.: stratum E.g.: stratum pigmentosum pigmentosum retinaeretinae

Layer of the pigmented epithelial cells

?Type of the epithelium?

1.2.

3.

1.

2.

1.

2.

3.

The type of the gland?

Type of the acini? Name of the staining technique?

Name of the structure?

Type of the acini? Name of the staining technique?

Name of the structure?

1.

2.

3.

4.

5.

1.1. Stratified columnar epithelium (male urethra)Stratified columnar epithelium (male urethra)2.2. Urothelium (ureter)Urothelium (ureter)3.3. Stratified squamous nonkeratinized epithelium and simple Stratified squamous nonkeratinized epithelium and simple

squamous epithelium (cornea)squamous epithelium (cornea)4.4. Pseudostratified epithelium and multicellular Pseudostratified epithelium and multicellular

endoepithelial mucinous gland (inferior concha nasalis)endoepithelial mucinous gland (inferior concha nasalis)5.5. Goblet cells stained with PAS (small intestine)Goblet cells stained with PAS (small intestine)6.6. Simple columnar epithelium with goblet cells (small Simple columnar epithelium with goblet cells (small

intestine)intestine)7.7. Simple cuboidal epithelium (medullary zone of the Simple cuboidal epithelium (medullary zone of the

kidney)kidney)8.8. Stratified squamous keratinized epithelium (skin)Stratified squamous keratinized epithelium (skin)9.9. Stratified columnar epithelium (male urethra)Stratified columnar epithelium (male urethra)10.10. Stratified squamous keratinized epithelium (str. Stratified squamous keratinized epithelium (str.

granulosum (1.), lucidum (2.), corneum(3.)granulosum (1.), lucidum (2.), corneum(3.)11.11. Simple columnar epithelium (gallbladder)Simple columnar epithelium (gallbladder)12.12. Stratified squamous keratinized epitheliumStratified squamous keratinized epithelium13.13. Simple columnar epithelium HE + goblet cells (1.), brush Simple columnar epithelium HE + goblet cells (1.), brush

border (2.) stained with PAS (duodenum)border (2.) stained with PAS (duodenum)14.14. Stratified squamous keratinized epithelium (str. Stratified squamous keratinized epithelium (str.

granulosum,granulosum, lucidum,lucidum, corneum)corneum)

15.15. Stratified columnar epithelium + multicellular Stratified columnar epithelium + multicellular endoepithelial gland (male urethra)endoepithelial gland (male urethra)

16.16. Mesothelium (Ag) (mesenterium)Mesothelium (Ag) (mesenterium)17.17. Mucinous acini + ductus salivaris stained for mucin Mucinous acini + ductus salivaris stained for mucin

(mucicarmin) (glandula subligualis)(mucicarmin) (glandula subligualis)18.18. Mucinous acini + ductus salivaris (HE) (gl. sublingualis)Mucinous acini + ductus salivaris (HE) (gl. sublingualis)19.19. Urothelium with umbrella cells (urinary bladder)Urothelium with umbrella cells (urinary bladder)20.20. Serous acini (parotis)Serous acini (parotis)21.21. Pseudostratified ciliated epithelium + goblet cells (1.) + Pseudostratified ciliated epithelium + goblet cells (1.) +

demilune of Gianuzzi (2.) + serous acini (3.) + duct (4.) demilune of Gianuzzi (2.) + serous acini (3.) + duct (4.) + mucinous acinus (5.) (respiratory tract)+ mucinous acinus (5.) (respiratory tract)

22.22. Stratified squamous nonkeratinized epithelium Stratified squamous nonkeratinized epithelium (esophagus, vagina)(esophagus, vagina)

23.23. Pseudostratified ciliated epithelium (tail of the Pseudostratified ciliated epithelium (tail of the epididymis)epididymis)

24.24. Urothelium with umbrella cells (urinary bladder)Urothelium with umbrella cells (urinary bladder)25.25. Simple columnar epithelium (uterus)Simple columnar epithelium (uterus)