Epithelial Tissue 2 Histology

Epit h e lia l t issu e s I I .

St r a t ifie d squ a m ou s n on k e r a t in ize d e pit h e liu m St r a t ifie d squ a m ou s k e r a t in ize d e pit h e liu m St r a t ifie d colu m n a r e pit h e liu m Tr a n sit ion a l e pit h e liu m Un ice llu la r gla n d Ex ocr in e gla n d

Stratified squamous nonkeratinized epithelium 1.: 1.

I t s ce lls for m t h r e e la ye r s: St r a t u m ge r m in a t ivu m / ba sa le / cylin dr oce llu la r e Consists of a single row of columnar cells resting on the basal lamina. The intense mitotic activity is responsible for the replacement of the removed cells from the surface. The junction of the epithelium and connective tissue is irregular, the interdigitations of connective tissue called papillae between evagination of the epithelium enhance the adhesion of the two tissue types.

2. Stratum spinosum: Consists of polygonal cells bound together by desmosomes. As a consequence of tissue preparation, the cells decrease in size and remain bound by desmosomes located at the tips of spiny cellular projections; the name of this layer is suggestive for this spine-studded appearance 3. Stratum planocellulare: Flattened cells that retain their nuclei. Location: Oral cavity, esophagus Vagina The corneal epithelium

lumen

Str. planocellulare

epithelium Str. spinosum Str. germinativum

Layers: 1 .Stratum basale (germinativum): For m e d by colu m n a r ce lls pr e se n t in g in t e n se m it ot ic activity 2.Stratum spinosum: Polygon a l ce lls a r e a lik e t h ose of t h e n on k e r a t in ize d epithelium. 3.Stratum granulosum: Con sist s of fla t t e n e d ce lls w it h ba soph ilic k e r a t oh ya lin granules. 4.Stratum lucidum: Tr a n slu ce n t , t h in la ye r of e osin oph ilic ce lls la ck in g n u cle i. 5.Stratum corneum: Keratinized nonnucleated cells, horny cells, that are continuously shed at the surface. Location: the epidermis of the skin

epithelium Str. corneum Str. lucidum Dermis Str. granulosum

Str. spinosum Hypodermis Str. germinativum

Stratified cuboidal epithelium: present in the duct of the sweat gland. Urothelium/ transitional epithelium: Layers: 1. Columnar cell layer 2. Polygonal cells/ pear-shaped cells 3. Domelike facet cells, also called umbrella cells Location: Renal pelvis Urinary bladder Upper part of the urethra

Umbrella cells Lumen

epithelium

Columnar cells

Polygonal cells

The superficial layer consists of columnar cells, while cuboidal or smaller columnar cells are present in the basal layer. Location: The bulbous part of the male urethra Conjunctiva Interlobular excretory ducts of glands

Columnar cell layer

Lumen

I t is for m e d by ce lls spe cia lize d t o pr odu ce a flu id se cr e t ion . Type s of gla n du la r e pit h e lia : En docr in e glands: ductless glads, their secretion is picked up and transported by the bloodstream, or diffuses into the surrounding extracellular fluid and acts on the neighbouring target cells (paracrine effect). Their secretions are called hormones. Ex ocr in e glands: usually present ducts through which the secretory product passes to reach the surface.

Ge n e r a l st r u ct u r e of t h e e x ocr in e gla n d:

Secretory portion (acinus): its shape may be acinar, tubular, tubuloacinar. Duct: it is unbranched in simple glands, and repeatedly branched in compound glands.

Cla ssifica t ion of t h e e x ocr in e gla n ds a ccor din g t o t h e ir position: endoepithelial, exoepithelial. Cla ssifica t ion of t h e e x ocr in e gla n ds a ccor din g t o t h e chemical nature of the secretion:

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

Cla ssifica t ion of t h e e x ocr in e gla n ds a ccor din g t o t h e m e ch a n ism of se cr e t ion : Merocrine mechanism: the secretion product is present in granules sorrounded by membranes, and it is released by exocitosis. E.g.: salivary glands. Apocrine mechanism: the secretion is eliminated together with the apical portion of the cytoplasm. E.g.: release of the lipid component of the secretion in lactating mammary gland. Holocrine mechanism: the entire secretory cell tranforms in secretion. E.g.: sebaceous gland.

Intestinal villus

Intestinal lumen

PAS-positive brush border

PAS-positive mucin droplets

Demilune of Gianuzzi Mucinous acini

Serous acini

Ductus salivaris

Hair cells in the organ of Corti

Receives external stimuli It is composed of modified epithelial cells, which represent a transition between epithelial and nerve cells. Classification of the cells of the neuroepithelium: Primary sensory cell (neuroepithel cell): presents process. E.g.: cells of the olfactory epithelium Secondary sensory cell (neuroepithel cell): does not present processes, stimuli pass on neural ganglia. E.g.: taste buds, hair cells of the internal ear

Layer of the pigmented epithelial cells

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

Type of the epithelium?

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The type of the gland?

Name of the structure?

Type of the acini? Name of the staining technique?

Name of the structure?

Type of the acini? Name of the staining technique?

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Stratified columnar epithelium (male urethra) Urothelium (ureter) Stratified squamous nonkeratinized epithelium and simple squamous epithelium (cornea) Pseudostratified epithelium and multicellular endoepithelial mucinous gland (inferior concha nasalis) Goblet cells stained with PAS (small intestine) Simple columnar epithelium with goblet cells (small intestine) Simple cuboidal epithelium (medullary zone of the kidney) Stratified squamous keratinized epithelium (skin) Stratified columnar epithelium (male urethra) Stratified squamous keratinized epithelium (str. granulosum (1.), lucidum (2.), corneum(3.) Simple columnar epithelium (gallbladder) Stratified squamous keratinized epithelium Simple columnar epithelium HE + goblet cells (1.), brush border (2.) stained with PAS (duodenum) Stratified squamous keratinized epithelium (str. granulosum, lucidum, corneum)

15. 16. 17. 18. 19. 20. 21.

22. 23. 24. 25.

Stratified columnar epithelium + multicellular endoepithelial gland (male urethra) Mesothelium (Ag) (mesenterium) Mucinous acini + ductus salivaris stained for mucin (mucicarmin) (glandula subligualis) Mucinous acini + ductus salivaris (HE) (gl. sublingualis) Urothelium with umbrella cells (urinary bladder) Serous acini (parotis) Pseudostratified ciliated epithelium + goblet cells (1.) + demilune of Gianuzzi (2.) + serous acini (3.) + duct (4.) + mucinous acinus (5.) (respiratory tract) Stratified squamous nonkeratinized epithelium (esophagus, vagina) Pseudostratified ciliated epithelium (tail of the epididymis) Urothelium with umbrella cells (urinary bladder) Simple columnar epithelium (uterus)