2. Basic Histology Quiz - Epithelium Created by: Maureen Bain Start

3. Question 1 Figure 1 shows a high power view of a small artery. What type of epithelium is represented by (1). Give a reason why this type of epithelium functionally suited to this location? For Info: The wall of the artery is completed by 2-3 layers of circumferentially arranged smooth muscle (2) and an adventitia (3) consisting of collagen and elastic fibres (connective tissue). There are therefore 3 types of tissue comprising the wall of this blood vessel. Answers at end of Quiz BackNext 123

4. Question 2 Figure 2 represents an image taken from a section of the kidney. A renal corpuscle (glomerulus and bowman’s capsule) is shown. What type of epithelium lines the parietal layer of the Bowman’s capsule [see A]? Sections through the proximal and distal convoluted tubules are also shown in this image. [B] represents a section through a distal convoluted tubule. Classify this type of epithelium. Answers at end of Quiz BackNext

5. Question 3 Figure 3: represents an image taken from a section of the gall bladder. Classify the type of epithelium shown in this image [C]. c Answers at end of Quiz BackNext

6. Question 4 Figure 4: This image shows a higher power view of the epithelium which lines the lumen of part of the small intestine- the jejunum. How would you classify this type of epithelium? What is the functional role of the epithelium in this location? Answers at end of Quiz BackNext

7. Question 5 Figure 5 is an example of a bronchus which can be found in lung tissue. This is one of the larger conducting passageways of the lung and is lined by ciliated pseudo-stratified columnar epithelium. This type of epithelium is also called respiratory epithelium as it lines most of the respiratory passageways. Bronchi also have cartilage in their walls which makes them easy to see in a section of lung. What name is given to the simple glandular cells (E) which are inter-dispersed amongst the epithelial cells in this type of epithelium? What do you think is the function of these simple glandular cells might be? What do you think the function of the cilia might be in respiratory passageways e.g. bronchi? Answers at end of Quiz BackNext

8. Question 6 Figure 6: Un-stretched urinary bladder. The lumen of the urinary bladder is lined by a transitional epithelium. This is another example of a pseudostratified epithelium mainly found in structures associated with the urinary system. Give another name for this type of epithelium. Why is this type of epithelium suited to this location? Answers at end of Quiz BackNext

9. Question 7 Figure 7: Oesophagus. Classify the epithelium shown in this image. In terms of function why do you think the oesophagus is not lined by a simple squamous epithelium? Figure 7: Cranial oesophagus (dog) Answers at end of Quiz BackNext

10. Question 8 Figure 8: digital pad (dog). Is this an example of a simple or stratified epithelium? The pink amorphous material on the surface of the skin represents fully keratinized cells which lack a nucleus and any organelles. The outermost layer of ‘living cells’ are squamous in appearance. Given this information how then would you precisely classify this type of epithelium. Why do you think this type of epithelium is functionally suited to this region? Answers at end of Quiz BackNext

11. Question 9 Figure 9: Sweat glands can be found in the dermal layer (beneath the epithelium) of the dogs digital pad. The secretory portions of these simple coiled tubular glands resemble ‘hula hoops’. What type of epithelium lines these secretory units?. The duct of these types of glands consists of a double layer of cuboidal epithelium and deposit the secretory product (sweat) directly onto the surface of the skin in the case of the foot pad. Secretory part of highly coiled sweat gland Duct Figure 9 Dog digital pad- Simple coiled tubular sweat glands in dermal layer Answers at end of Quiz BackNext

12. Question 10 Figure 10 Salivary gland (parotid): This is an example of a compound acinar gland. This definition tells us that the duct system is branched and the secretory portion is flask like. In histological section the secretory portions will have have a round profile in cross section and should be quite distinct from the ducts. Based on staining reaction of the secretory product within the secretory cells is this an example of a serous or mucus secretory unit? Figure 10: Serous salivary gland (parotid)- example of compound acinar gland ductSecretory unit The approx location of the lumen of one secretory unit is shown (yellow circle) Answers at end of Quiz BackNext

13. Question 11 Figure 11 Submandibular gland. This is an example of a ‘mixed’ or seromucus gland. Both mucus and serous secretions are produced by the secretory cells in this gland. This particular gland is characterized by the presence of serous demilunes. Exocrine glands can also be classified as holocrine, merocrine and apocrine glands based on their mode of secretion. Which of these term is used to describe the secretory process where the whole cell is lost ? Figure 11: Sub-mandibular gland- mixed or seromucus gland with serous demilunes Serous part Mucus partdemilune The approx location of the lumen of one secretory unit is shown (yellow circle) Answers at end of Quiz BackNext

14. Answers 1. Simple squamous- required to be very smooth and to have low resistance to flow 2. Simple squamous Simple cuboidal- microvilli are present giving rise to the fuzzy pink border- these surface modifications are just about out with the resolution of the light microscope and increase the surface area available for resorption. 3. Simple columnar 4. Simple columnar ( Note the goblet cells interdispersed in between surface epithelial cells are an example of secretory epithelial cells). The simple columnar cells again have microvilli on their luminal surface which help increase the surface area of the cells for absorption. As above the microvilli give the cells a fuzzy edge on the luminal surface. Function is absorption of nutrients. 5. Goblet cells Produce mucus- which along with cilla form the mucocillary carpet. This traps debris coming in along with the air stream thus keeping the lower respiratory passageways free from dirt and exposure to potential pathogens. See last answer- note that cilia are much larger than the microvilli (see above) and can be visualized with the light microscope. Cilia are also motile and function to waft the mucus generated by the goblet cells plus trapped debris across the surface of the epithelium in the opposite direction away from the lower respiratory passageways. 6. Urothelium It is very stretchy Stretchy- cells slide past each other - they eventually would form a single layer if stretched enough. This allows the bladder to increase in size as urine accumulates, and is able to return to its normal shape when the bladder empties at micturition. 7. Stratified squamous- not usually keratinized The surface squames are continuously being lost due to abrasion in this type of epithelium. Note that the basal layer of this type of epithelium (next to the basement membrane) are mitotically active and that these move up through the layers to eventually reach the surface where they will then abraded away. 8. Stratified – consists of multiple layers Stratified squamous keratinized Excessive mechanical abrasion- keratin is a tough protein and by being present here it is protecting the underlying living tissues. But remember the cells underlying the keratinized layer will eventually end up being completely keratinized themselves at which point they are no longer living cells. 9. Simple cuboidal epithelium 10. Serous as take up the stain and are darkly stained (compare to mucus secreting glands) 11. Holocrine is where whole cell is lost when the secretory product is ready to be released Back to quiz