OSSF: Histology of the Epithelium
UPDATED ACTUAL Exam Questions and
CORRECT Answers
What are the 4 basic cell types that compose organs? - CORRECT ANSWER - 1) Epithelial
cells
2) Connective tissue
3) Muscle cells
4) Nervous cells
What are the general characteristics of epithelial cells (there are 4)? - CORRECT ANSWER -
1) Closely positioned and tightly connected to one another
2) Have functional polarity (a defined top and bottom)
3) Avascular (no blood vessels)
4) Supported by connective tissue
What are the common epithelial cell locations? - CORRECT ANSWER - - the skin (body
surface)
- lining body cavities (endothelial and mesothelial cells)
- Lining body tubes (alimentary tracts, respiratory tracts, and gastrointestinal tracts)
- forming secretory solid organs, glands, and ducts
What are endothelial cells and where are they found? - CORRECT ANSWER - They are
epithelial cells that line the lumen of blood vessels and lymphatics.
What are mesothelial cells and where are they found? - CORRECT ANSWER - Are epithelial
cells that line the body cavities and internal organs.
, What are the three germ layers that form from embryonic stem cells and what do they give rise
to? - CORRECT ANSWER - 1) Ectoderm: Gives rise to the skin.
2) Endoderm: Gives rise to the GI and respiratory tract.
3) Mesoderm: Gives rise to endothelial cells (blood vessels) and mesothelial cells (body cavities/
outside of organs).
Which type of embryonic tissue contains cytokeratin? - CORRECT ANSWER - Epithelial
cells from the Endoderm and ectoderm (never the mesoderm).
Which type of embryonic tissue contains vimentin? - CORRECT ANSWER - Mesenchymal
cells from the mesoderm.
Where are the basal, lateral, and apical membranes of epithelial cells oriented? - CORRECT
ANSWER - Basal: rests on the basement membrane
Lateral: communicates with adjacent cells
Apical: Directed toward the surface of the lumen or enclosed body cavity.
What are epithelial specializations of apical surface (there are 4)? - CORRECT ANSWER -
Glycocalyx, microvilli, stereocilia, and cilia (motile and primary).
Glycocalyx - CORRECT ANSWER - IS a glycoprotein polysaccharide that covers the cell
membranes. They are present on ALL cells.
What is the glycocalyx important for? - CORRECT ANSWER - Protection, serving as a
permeability barrier, facilitating cell recognition, and providing cell adhesion.
What are the two stains that you can use to stain the glycocalyx? - CORRECT ANSWER -
Periodic Acid Schiff (PAS) and H&E.
UPDATED ACTUAL Exam Questions and
CORRECT Answers
What are the 4 basic cell types that compose organs? - CORRECT ANSWER - 1) Epithelial
cells
2) Connective tissue
3) Muscle cells
4) Nervous cells
What are the general characteristics of epithelial cells (there are 4)? - CORRECT ANSWER -
1) Closely positioned and tightly connected to one another
2) Have functional polarity (a defined top and bottom)
3) Avascular (no blood vessels)
4) Supported by connective tissue
What are the common epithelial cell locations? - CORRECT ANSWER - - the skin (body
surface)
- lining body cavities (endothelial and mesothelial cells)
- Lining body tubes (alimentary tracts, respiratory tracts, and gastrointestinal tracts)
- forming secretory solid organs, glands, and ducts
What are endothelial cells and where are they found? - CORRECT ANSWER - They are
epithelial cells that line the lumen of blood vessels and lymphatics.
What are mesothelial cells and where are they found? - CORRECT ANSWER - Are epithelial
cells that line the body cavities and internal organs.
, What are the three germ layers that form from embryonic stem cells and what do they give rise
to? - CORRECT ANSWER - 1) Ectoderm: Gives rise to the skin.
2) Endoderm: Gives rise to the GI and respiratory tract.
3) Mesoderm: Gives rise to endothelial cells (blood vessels) and mesothelial cells (body cavities/
outside of organs).
Which type of embryonic tissue contains cytokeratin? - CORRECT ANSWER - Epithelial
cells from the Endoderm and ectoderm (never the mesoderm).
Which type of embryonic tissue contains vimentin? - CORRECT ANSWER - Mesenchymal
cells from the mesoderm.
Where are the basal, lateral, and apical membranes of epithelial cells oriented? - CORRECT
ANSWER - Basal: rests on the basement membrane
Lateral: communicates with adjacent cells
Apical: Directed toward the surface of the lumen or enclosed body cavity.
What are epithelial specializations of apical surface (there are 4)? - CORRECT ANSWER -
Glycocalyx, microvilli, stereocilia, and cilia (motile and primary).
Glycocalyx - CORRECT ANSWER - IS a glycoprotein polysaccharide that covers the cell
membranes. They are present on ALL cells.
What is the glycocalyx important for? - CORRECT ANSWER - Protection, serving as a
permeability barrier, facilitating cell recognition, and providing cell adhesion.
What are the two stains that you can use to stain the glycocalyx? - CORRECT ANSWER -
Periodic Acid Schiff (PAS) and H&E.
