Histology SDL Flashcards
3 components of nasal cavity?
- Olfactory area
- Conchae
- Vestibule
Organ of phonation?
Larynx
2 portions of pharynx?
- Nasopharynx
- Oral pharynx
Diameter of bronchioles?
1 mm or less
Manner in which bronchi branch?
In a dichotomous fashion
What does this show?
Nasal vestibule of nasal cavities
SEM showing the transition from outside fully keratinized stratified squamous epithelium at green arrow to non-keratinized stratified squamous epithelium at the yellow arrow
What is this?
SEM of respiratory epithelium in more protected regions of the nasal cavities: a pseudostratified columnar epithelium characterized among other things by numerous “goblet cells” (seen at the green arrow) dispersed among numerous “ciliated cells” (seen at the red arrow)
What is this?
This is a very well preserved H&E stained section of the respiratory epithelium:
- Black arrows: mucin within goblet cells
- Red arrow: the nucleus of a goblet
- Larger green arrow: the nucleus of a ciliated cell situated higher in the epithelium than goblet cell nuclei
- Smaller green arrow: nucleoli of the ciliated cells
- Blue arrow: numerous cilia can be seen on the free surfaces of the ciliated cells
- Small yellow arrow: numerous basal bodies subjacent to cilia
- Purple arrow: basal cell
- Large yellow arrow: thick basement membrane on which the respiratory epithelium rests
- Two headed pink arrow: prominent layer of connective tissue termed the lamina propria
Respiratory epithelium: which are the most basally located cells? Describe them. Describe the layers of the respiratory epithelium.
The most basally located cells are the basal cells that are progenitor cells that can give rise to ciliated or goblet cells when the need arises. Therefore, you have three layers of cell nuclei at different levels in the epithelium that nevertheless all rest upon the same basement membrane.
What is this?
Typical H&E stained section of the respiratory epithelium.
- Large black arrows: regions within goblet cells that once contained mucin that has been leached out as a result of histological processing with organic solvents
- Smaller black arrows: goblet cell nuclei
- Yellow arrow: one many basal cell nuclei.
- Small blue arrow: nucleus of a ciliated cell that is located higher in the epithelium than goblet cell and basal cell nuclei
- Larger blue arrow: cilia emerging from the surfaces of ciliated cells
- Large green arrow: thick basement membrane upon which the respiratory epithelium rests
- Under this basement membrane is connective tissue of the lamina propria
What is this?
SEM showing a region of the respiratory epithelium that has been denuded of all but a few ciliated cells
- Red arrow: ciliated cells
- Yellow arrows: apical portions of goblet cells that are swollen due to accumulated mucin => as the accumulated mucin expands the apical plasmalemma, apical microprojections become incorporated into this membrane => apical microprojections accumulate along the cell borders, demarcating these borders and revealing the hexagonal or pentagonal surface outlines of these cells
- Green arrows: small “brush cells” dispersed between adjacent goblet cells ( identified by their brush-like microvilli on their apical surfaces)
What is this?
TEM thin section showing the apical portion of the respiratory epithelium
- Labeled “G”: goblet cell seen filled with numerous mucin granules
- Red arrow: swollen apical portion of a goblet cell
- Blue arrow: one of many cilia that can be seen projecting from the apical surfaces of the ciliated cells
- Yellow arrow: basal bodies supporting the cilia
- Black arrow: mitochondrion of a ciliated cell
Which cells of the respiratory epithelium contain many mitochondria?
Both ciliated and goblet cells
TEM showing two brush cells, both labeled “B” with microvillous projections emerging from the apical portions
- Arrows: apical intercellular junctions between adjacent cells
What would you see if you looked into the nasal cavities?
- Pinkish-red surface due to blood in the underling vessels
What are the nasal conchae? Why are they called like this? List them.
Purpose?
Which ones are covered with respiratory epithelium?
3 shelf-like structures projecting from the lateral walls of each nasal cavity that have been termed “conchae” because they curl downward, not unlike shells
- The upper or superior conchae
- The middle conchae***
- The lower or inferior conchae***
Purpose: help create turbulence of the air entering the nasal cavities, thereby facilitating contact of the incoming air with the respiratory epithelium
What is found within conchae? Where exactly? Role?
Large venous plexus termed “swell bodies” in the lamina propria of the conchae, which can become engorged with blood and result in a “stuffy nose”
Regulate the flow of air
If you were to look at the roof of the nasal cavity, how would it appear? What is this?
Yellowish-brown in contrast to the reddish tint of the surrounding respiratory epithelium => this is the “olfactory region” of the nasal cavity specialized for the sense of smell
Where is the olfactory epithelium in the nasal cavities?
Extends from the middle roof of the nasal cavity over the upper surface of the superior conchae and upper lateral side of the nasal septum
What is this?
H&E stained section taken through a portion of the superior conchae
- a: olfactory epithelium
- b: numerous serous glands = the “glands of Bowman” in connective tissue under the olfactory epithelium
- c: respiratory epithelium
- d: bone
- Arrows from the small letter “e”: bundles of nerve fibers arising from the olfactory cells that have been termed “fila olfactoria”
Purpose of glands of Bowman?
The watery secretions from these serous glands help bath the surface of the olfactory epithelium thereby facilitating the sensing of new odiferous compounds (cleansing of olfactory region)
What is this? Describe each.
Olfactory epithelium with 3 basic cell types =
- Supporting or “sustentacular cells” that contain a brownish pigment similar to lipofucsin and gives the olfactory region its yellowish-brown color
- Bipolar neurons making up the sensory “olfactory cells”, and the “basal cells”
- Duct from passing through the olfactory epithelium and arising from an underlying serous gland of Bowman
What kind of epithelium is the olfactory one?
Since all three of these cell types rest on the same basement membrane, this epithelium, like the respiratory epithelium, is a pseudostratified columnar epithelium
H&E section through a region of the olfactory epithelium
- Bracket: olfactory epithelium
- Small black arrows: serous glands of Bowman
- Larger back arrows: bundles of nerve fibers making up the fila olfactoria
What is this?
TEM thin section through the apical aspect of the olfactory epithelium
- Small back arrows: “sensory cilia” emerging from the “olfactory vesicle”
How many sensory cilia arise from each olfactory cell? How far do they extend? Arrangement of cilia?
- 10 to 15 of these nonmotile sensory cilia arise from each olfactory cell
- Extend for long distances (i.e., 100 to 200 microns) parallel to the surface of the mucosa
- Begin with the 9+2 microtubule arrangement, they become thinner and may have only one or two microtubules in their tapered ends
What is this?
TEM higher magnification image of a cross-section through the ends of sensory cilia (arrows) mixed with microvillous projections from sustentacular cells. You can make out cross-sectional images of one and two microtubules in the tapered ends of the sensory cilia
What is this?
Longitudinal H&E stained section through the true and false vocal cords
- “a”: non-keratinized stratified squamous epithelium
- “b”: false vocal cord
- “c”: ?
- “d”: large vocalis muscle = the “true vocal cord”
- “e”: ventricle
- “f”: thyroid cartilage
What is a true vocal cord of the larynx covered with? Why?
Covered by a non-keratinized stratified squamous epithelium due to the trauma associated with phonation
What is the false vocal cord of larynx covered by? What does it contain?
Covered by respiratory epithelium and contains numerous sero-mucous glands
Role of thyroid cartilage of larynx?
Provides support
What is the ventricle of the larynx? What is it covered by?
Protected region between the true and false volcal cords lined by respiratory epithelium
Thickness of olfactory epithelium compared to respiratory?
Much thicker
How long is the trachea? Diameter?
Start? End?
- 11 cm long
- 2-2.5 cm in diameter
- Starts at the larynx
- Ends by dividing into two primary bronchi that enter the “roots” or “hilar region” of the lungs
What is this?
Low magnification H&E stained cross-section through the trachea.
- Small blue arrows: lining respiratory epithelium
- Small black arrows: extensive serous mucous glands in the submucosa
- Large black arrow: piece of the “trachealis muscle”
- C: cartilage
Role of trachea cartilage?
Provides flexible mechanical support
What is this?
Higher magnification toluene blue stained section of through the apical aspect of the tracheal lumen showing the:
- respiratory epithelium
- underlying connective tissue
- smooth muscle
- hyaline cartilage
- serous glands
Do the primary bronchi have the same histological characteristics as the trachea?
YUP
Evolution of cartilage after the bronchi enter the lungs?
The cartilage rings that support the bronchi, break up into cartilage plates
What is this?
H&E stained section through a portion of an intrapulmonary bronchus
- Green arrow: respiratory epithelium
- Yellow arrow: smooth muscle
- Blue arrow: piece of the hyaline cartilage plate that supports the bronchus
Bronchi smooth muscle: where is it originally derived from? How does it wind down the bronchi?
Derived originally from the trachealis muscle
Winds down the bronchi in a spiral fashion
Do bronchioles have glands in the lamina propria?
NOPE
Respiratory epithelium of bronchioles?
Significantly reduced respiratory epithelium with few, if any, goblet cells.
What is this?
H&E cross-section through a bronchiole
- Black arrow: reduced respiratory epithelium
- Blue arrow: prominent layer of smooth muscle, characteristic of bronchioles
What are terminal bronchioles lined by?
- Dome-shaped secretory cells termed “Clara cells”
- Shorted ciliated cells
Lining epithelium of respiratory bronchioles? What is it characterized by?
Simple columnar or cuboidal characterized by short cilia
What is this?
Low magnification SEM view of the lungs showing:
- terminal bronchioles (at “T”)
- respiratory bronchioles (at “R”)
- Alveolar duct at “D”
- blood vessel at “V”