Respiratory Histology

Question 1

Answer 1

RESPIRATORY EPITHELIUM (TOLUIDINE BLUE)

• nuclei, ribosomes - dark blue, cytoplasm - blue
• ciliated cells
• non-ciliated goblet cells
• underlying tissue rich in blood vesseld (temp and humidity) and sero-muscous glands (secretions via ducts)
• mucous prevents dehydration of epithelium and traps particulate matter

SIMPLE/PSEUDO-STRATIFIED COLUMNAR CILIATED EPITHELIUM

with non-ciliated (basal/intermediate) stem cells - renewal of epithelium

@nose, nasopharynx, larynx, trachea, bronchi, bronchioles

Question 2

Answer 2

NOSE (H&E AND ALCIAN BLUE)

• mucous/cartilage - blue
• central bone plate - pink
• respiratory epithelium either side
• thin walled blood vessels between epithelium and bone
• mucous containing goblet cells stained bright blue

Question 3

Answer 3

NOSE OVERVIEW

• simple ciliated respiratory epithelium except at opening (hairy skin)
• concha covered in respiratory epithelium
• swell bodies - thin arterioles/venules deep to epithelium (nose bleeds)
• thin skin allows the escape of water (moistening air)

Question 4

Answer 4

OLFACTORY EPITHELIUM

• @ roof of nose below cribriform plate
• pseudo-stratified columnar epithelium with basal and sustentacular (supporting cells)
• with bipolar neurons - dendritic process to surface (arrow)
• serous glands to surface (solvent for odorous substances)
• thicker than other respiratory epithelium

special cells = Bowman’s glands - small serous glands below olfactory epithelium

sustentacular cells tall, narrow, in contact w/ BM. bulky cytoplasm near lumen. cytoplasm accumulates yellow/brown pigment.

Question 5

Answer 5

LARYNX

• respiratory epithelium, except vocal folds
• vocal folds - stratified squamous epithelium (more robust, may withstand vibration)

below epiglottis larynx -> 2 sets of folds

Vocal folds

• contain free upper margin of elastic tissue (conus elasticus)
• tensioned by voluntary skeletal muscle - vocalis muscle

FALSE FOLDS - upper - respiratory epithelium

TRUE FOLDS - lower - stratified squamous epithelium

VESTIBULE - between - respiratory epithelium

Question 6

Answer 6

TRACHEA

• pseudo-stratified, ciliated, columnar epithelium

Question 7

Answer 7

VOCAL CORDS

• stratified squamous epithelium

Question 8

Answer 8

VOCAL FOLDS 2

• red arrow points to voluntary skeletal muscle
• green arrow points to sero-mucous glands

Question 9

Answer 9

TRACEHA 2

• lumen of trachea = top
• C-shaped cartilage = bottom
• epithelium = pseudo-stratified columnar epithelium
• note serous glands visible which secrete to surface
• with H&E, goblet cells stain white

Question 10

Answer 10

BRONCHUS (H&E)

• respiratory epithelium
• held open by hyaline cartilage framework (dark stain) which appear as isolated islands
• smooth muscle band under epithelium
• lymph nodules (MALT- mucosa associated lymph tissue) @ connective tissue

Question 11

Answer 11

MALT NODULE (@ TRACHEA)

• left arrow points to MALT nodule
• right arrow points to smooth muscle band

LYMPH NODE = discrete, encapsulated collection of lymphoid tissue

MALT NODULE = no capsule, intimately related to epithelium

Question 12

Answer 12

BRONCHIOLES

• simple ciliated respiratory epithelium
• no hyaline cartilage
• smooth muscle
• lymph nodules
• closely associated arteries and veins (branches of pulmonary artery/vein)
• no goblet cells

unlike bronchi may be contstricted by smooth muscle as no cartilage

Question 13

Answer 13

TERMINAL/RESPIRATORY BRONCHIOLES (not respiratory epithelium)

terminal

• SIMPLE CUBOIDAL EPITHELIUM
• sparsely ciliated
• CLARA CELLS - many large ribosomes, ER, and granules -> function is secretory and synthetic
• sphincter-like smooth muscle ring

respiratory

• SIMPLE CUBOIDAL EPITHELIUM
• larger than terminal - beginning of respiratory portion of lung

this slide - terminal

Question 14

Answer 14

ALVEOLI

• walls = capillaries between simple squamous epithelium
• fibroblasts in walls - produce type 3 collagen (reticulin) and elastic tissue (recoil)
• adjoining alveoli connected by pores = equal inflation

type 1 cells (thin) - flat cells, flat nuceli, 40% of population, 90% of SA

type 2 cells (globular) - secretes surfactant (lipid rich), 60% of pop., 10% SA, rounded, round dark staining nuclei

Question 15

Answer 15

ALVEOLAR MACROPHAGES

• free roam in alveoli - phagocytose particulate matter and cell debris
• from monocytes in blood
• other macrophages stay in lung substance and engulf material that enters alveoli wall
• contain black ingested dust (carbon) particles

ALVEOLAR - enter teminal/respiratory bronchioles and pass to lymphatics or are transported by muco-ciliary escalator

FIXED/SEPTAL - remain in interstitium between cells and tissue

Question 16

Answer 16

TYPE 2 PNEUMOCYTE

• A - alveolus
• BL - basal lamina (basement membrane)
• EP and EP1 - type 1 pneumocyte
• G - surfactant containing granules

Question 17

Answer 17

PULMONARY BLOOD VESSELS

• large pulmonary blood vessels accompany bronchi
• indistinguishable from systemic counterparts EXCEPT large pulmonary arteries have longitudinally running elastic fibers in wall
• large pulmonary veins w/ clearly defined medial layeer of muscle and elastic tissue and well-defined internal elastic lamina