Histology of Epithelial Tissue Flashcards
Tissue group with the characteristics:
- formed by epithelial cells
- consists of cells closely adherent to one another
- cells extremely cohesive
- avascular
- provided with basement membrane (BM) or a basal lamina
- for covering or for glands
Epithelial tissue
The germ layer(s) from which epithelial tissue is derived
ALL THREE GERM LAYERS:
- ectoderm
- mesoderm
- endoderm
Germ layer from which the epidermis of the skin and the corneal epithelium derive
Ectoderm
Forms the epidermis, corneal epithelium, oral/anal canal lining, the CNS, and the neural crest derivatives
Germ layer from which the lining epithelium of the kidneys and reproductive tracts derive
Mesoderm
(Forms the renal epithelium, the lining epithelium of the reproductive tracts, the connective tissues (bones, cartilages, muscles), the CVS, blood, body cavity lining, and the urogenital system)
Germ layer from which the lining epithelium of the GIT and respiratory system forms
Endoderm
Class of epithelial tissue that functions as a “covering” - a membranous layer that covers the external/internal surfaces of the body
Surface epithetlium (of covering epithelium)
Type of surface epithelium lined by a single layer of cells
Simple epithelium
Type of simple epithelium described as a single layer of FLAT cells, and is well-adapted for exchange, lubrication, and filtration
Simple squamous epithelium
Type of simple epithelium that’s found in the:
- endothelium of the BV
- mesothelium of body cavities
- parietal layer of the Bowman capsule
- alveoli of the lung
- corneal endothelium
Simple squamous epithelium
Type of simple epithelium described as a single layer of CUBOIDAL cells, well-adapted for absorption
Simple cuboidal epithelium
Type of simple epithelium that’s found in the:
- tubules of the kidneys
- germinal epithelium of the ovaries
- lining of the lens
Simple cuboidal epithelium
Type of simple epithelium described as a single layer of TALL, COLUMNAR cells
Simple columnar epithelium
Type of simple epithelium that’s found in the:
- lining of the GIT up until the upper anal canal
Simple columnar epithelium
Vascularized connective tissue that serves as the source of nutrient to the avascular surface epithelium
Basement membrane (or basal lamina)
Type of surface epithelium lined by a several layers of cells, well-adapted for protective/barrier purposes
Stratified epithelium
Type of stratified epithelium made of several layers of FLAT cells
Stratified squamous epithelium
Subtype of stratified squamous epithelium in which the cells undergo keratinization to develop a more tough, protective outer layer/structure; seen in the epidermis and its appendages
Cornified stratified squamous epithelium
Subtype of stratified squamous epithelium that normally does not undergo keratinization, found lining the esophagus, vagina, anal canal, and the corneal epithelium
Non-cornified stratified squamous epithelium
Type of surface epithelium that is a modification of the simple epithelium in which all cells adhere to the basal lamina, but not all of them reach to form an apical surface; cell shapes may vary, forming a “false stratification”, and the different cell types may have different structures: ciliated, stereo-ciliated, non-ciliated
Pseudostratified columnar epithelium
Special type of simple squamous epithelium that lines the inner surfaces of blood and lymphatic vessels
Endothelium
Special type of simple squamous epithelium that lines the inner surfaces of the visceral organs
Mesothelium
Special type of pseudostratified columnar epithelium that lines the respiratory tract, made up of an admixture of 3 types of cells (ciliated pseudostratified columnar cells, basal cells, and the mucin-secreting merocrine goblet cells)
Respiratory epithelium (or the pseudostratified columnar epitherlium with goblet cells)
Type of surface epithelium that is a modification of the simple epithelium in which the number of cell layers vary with the functional state of the organ
Transitional epithelium
Special type of transitional epithelium that lines the ureters, bladder, and urethra with characteristically thick layers of protective glycoproteins at its apical/luminal surface and a high elasticity
Urothelium (or uroepithelium)
Class of epithelial tissue that is the main component of GLANDS
Glandular epithelium
Type of gland (based on shape) that retains its shape throughout its length
Tubular gland
Type of gland (based on shape) that has a sac-like secretory portion at/near the end of its length
Alveolar gland (or saccular gland)
Type of gland formed by an aggregation of glandular epithelia that produces and secretes its secretions onto an epithelial surface via a duct
Exocrine gland
Type of gland formed by an aggregation of glandular epithelia surrounded by a highly vascular environment that produces and secretes its secretions directly into the bloodstream
Endocrine gland
Exocrine mechanism in which secretions of the cell are secreted via exocytosis, onto an epithelial surface
Merocrine
(Includes:
- salivary glands
- exocrine pancreatic glands
- eccrine sweat glands [majority of skin])
Exocrine mechanism in which secretions of the cell are secreted via the budding-off of the secretory cell, onto an epithelial surface
Apocrine
(Includes:
- lactating mammary glands
- apocrine sweat glands [axilla, perianal area]
- ciliary glands of the eyelids
- ceruminous glands of the ear)
Exocrine mechanism in which secretions of the cell are secreted via the complete maturation and death/destruction of the secretory cell itself, becoming the secretory product released on an epithelial surface
Holocrine
(Includes:
- sebaceous glands
- Meibomian glands of the eyelids)
Transformation of one tissue type to another
i.e.: In chronic irritation, stratified squamous epithelium may replace other epithelial cell types
Metaplasia
A malignant neoplasm, an abnormal/uncontrolled growth, made up of surface epithelial cells; malignancy that arises from surface epithelia
Carcinoma
A benign neoplasm, an abnormal/uncontrolled growth, arising from surface epithelial cells
Papilloma
A benign neoplasm, an abnormal/uncontrolled growth, arising from glandular epithelial cells
Adenoma
A malignant neoplasm, an abnormal/uncontrolled growth, made up of glandular epithelial cells; malignancy that arises from glandular epithelia
Adenocarcinoma
Junctional complex found between adjacent epithelial cells especially in the GIT, blood-and-brain, CSF-and-brain, blood-and-testis; (responsible for barriers)
Zonula occludens or:
- occluding junctions
- tight junctions
Junctional complex found between cardiac muscle (intercalated discs)
Zonula adherens
Junctional complex found between stratified epithelium (such as the epidermis), maintaining close association of cells
Macula adherens or:
- desmosomes
Junctional complex that utilizes a space for transfer of signals for communications; found between nerves, muscles-and-nerves, etc.
Nexus or:
- gap junctions
- synapse (if between neuron axon terminal and another neuron’s dendrite)
- autapse (special synapse between neuron axon terminal and its own dendrite)
- ephapse (if between nerve membrane to nerve membrane over a point of contact other than the synapse)
