Histology of Epithelial Tissue Flashcards by Vincent Ribaya

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

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The germ layer(s) from which epithelial tissue is derived

ALL THREE GERM LAYERS:

ectoderm
mesoderm
endoderm

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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

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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)

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Germ layer from which the lining epithelium of the GIT and respiratory system forms

Endoderm

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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)

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Type of surface epithelium lined by a single layer of cells

Simple epithelium

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Type of simple epithelium described as a single layer of FLAT cells, and is well-adapted for exchange, lubrication, and filtration

Simple squamous epithelium

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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

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Type of simple epithelium described as a single layer of CUBOIDAL cells, well-adapted for absorption

Simple cuboidal epithelium

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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

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Type of simple epithelium described as a single layer of TALL, COLUMNAR cells

Simple columnar epithelium

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Type of simple epithelium that’s found in the:

- lining of the GIT up until the upper anal canal

Simple columnar epithelium

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Vascularized connective tissue that serves as the source of nutrient to the avascular surface epithelium

Basement membrane (or basal lamina)

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Type of surface epithelium lined by a several layers of cells, well-adapted for protective/barrier purposes

Stratified epithelium

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Type of stratified epithelium made of several layers of FLAT cells

Stratified squamous epithelium

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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)