22-09-21 - Epithelia

Question 1

Which intracellular structures does haematoxylin stain?

Answer 1

• Negatively charged structures such as DNA and RNA

Question 2

What is the chemical nature of substances stained by PAS?

Answer 2

• Saccharide structures of glycoproteins

Question 3

What cell types will be PAS positive?

Answer 3

• Any cells containing the accumulation of glycoproteins/mucus
• This includes:
• Goblet cells
• Mucus secretory cells
• Exocrine glands

Question 4

Where is the basal lamina found (basement membrane)?

Is it PAS positive?

Answer 4

• Located at the base of the epithelia
• It is PAS positive due to the presence of glycoproteins

Question 5

Where can you find simple squamous epithelia?

What type of squamous epithelia is present?

What is its function in these structures?

Answer 5

• Lining blood vessels and lymphatics – Mesothelium – low friction, selective barrier for passage of immune cells and fluid
• Body cavities – Endothelium – low friction (for efficient transport of blood) selective barrier for diffusion of metabolites, gases and passage of immune cells

Question 6

What type of epithelium lines the GI tract?

What modification does this lining allow?

Answer 6

• Modified columnar
• Possesses absorptive cell microvilli
• Gives secretory capability for secretion of mucus

Question 7

What type of epithelium lines the trachea and bronchi? What modification does this lining bring?

Answer 7

• Pseudostratified epithelium
• Provides Cilia and allows for mucus secretion

Question 8

What special properties does transitional epithelium possess?

Answer 8

• Distensible (Capable of being swollen due to pressure -bloating)

Question 9

Why is pseudostratified epithelium called this?

Answer 9

• Gives appearance of multiple layers of cells but is actually only a single layer because all of the cells are connected to the basement membrane.

Question 10

What are the differences between exocrine and endocrine glands?

Answer 10

• Exocrine glands secrete onto a body surface (internal or external)
• Endocrine glands secrete into the blood stream

Question 11

What are the differences between mucous and serous glands?

Answer 11

• Mucous glands have flat dense nuclei (larger) and foamy cytoplasm
• Serous glands have a round vesicular nucleus (smaller) and eosinophilic cytoplasm/granules
• Eosinophils are white blood cells involved in the body’s immune response

Question 12

Fill in these questions with this list:

• This surface modification contains actin filaments.
• This type of epithelium is found in the urinary tract.
• This type of cell surface modification contains microtubules.
• This substance is stored in goblet cells.
• This cell displays modifications which improve the efficiency of absorption.
• This type of epithelium lines blood vessels.

Amylase

Cilia

Mucus

Microvilli

Transitional epithelium

Squamous cell

Goblet cell

Mesothelium

Endothelium

Stratified squamous epithelium

Respiratory epithelium

Basement membrane

Stomach epithelium

Intestinal absorptive cell

Answer 12

This surface modification contains actin filaments.

Microvilli

This type of epithelium is found in the urinary tract.

Transitional epithelium

This type of cell surface modification contains microtubules.

Cilia

This substance is stored in goblet cells.

Mucus

This cell displays modifications which improve the efficiency of absorption.

Intestinal

This type of epithelium lines blood vessels.

Endothelium