Histology Exam 2: Oral Cavity And Salivary Glands

Front 1

Describe the components of the lip.

Back 1

- outer integument: keratinized stratified squamous epithelium

- mucocutaneous region: dermis blends with propria-submucosa beneath the mucosal epithelium (which has no muscularis mucosae)

- mucosal epithelium: stratified squamous epithelium, keratinized in horses and ruminants, non-keratinized in carnivores and pigs

- serous and seromucinous minor salivary glands (labial glands) are distributed throughout the propria-submucosa

- muscular tunic with skeletal muscle, called orbicularis oris

Front 2

Describe components of the cheek.

Back 2

- cheek (vestibular) mucosa is underlain by buccal muscles

- in ruminants the mucosa is studded with buccal papillae

- buccal glands (minor salivary glands) are scattered in the propria-submucosa

Front 3

Describe components of the hard palate.

Back 3

- mucosa has a series of transverse ridges called rugae

- rostral part called the dental pad; thick mucosa, especially in ruminants

- in ruminants epithelium is thick and heavily cornified

- palatine salivary glands in the propria-submucosa

- caudal region has branched tubuloacinar mucous and seromucous glands

Front 4

Describe components of the soft palate.

Back 4

- palatine salivary glands in propria-submucosa

- ventral portion contains branched tubuloacinar mucous and seromucous glands

- ventral aspect covered with stratified squamous epithelium (similar to rest of oral cavity)

- dorsal aspect covered with pseudostratified ciliated columnar epithelium (like upper respiratory tract)

- core is striated muscle tissue

- mucosa of oral and nasal sides has diffuse and nodular lymphatic tissue

Front 5

Describe general composition of the tongue.

Back 5

- composed of skeletal muscle fibers arranged in different planes

- covered by mucous membrane: dorsal is rough, ventral is continuous with non- or poorly cornified stratified squamous epithelium of inter-mandibular ventral floor of oral cavity

- has propria-submucosa

Front 6

What is the lyssa?

Back 6

- cord-like longitudinal structure found in ventral midline of tongue of carnivores and pigs

- dense collagenous sheath filled with adipose tissue, skeletal muscle, blood vessels, nerves

- aids in "backwards scoop" for drinking

Front 7

What lingual structure similar to the lyssa does the horse have?

Back 7

- mid-dorsal fibroelastic cord with hyaline cartilage, striated muscle, fat

Front 8

Name the 6 types of lingual papillae.

Back 8

- filiform papillae
- conical papillae
- lenticular papillae
- fungiform papillae
- vallate or circumvallate papillae
- foliate papillae

Front 9

Which types of lingual papillae have taste buds?

Back 9

- fungiform papillae
- vallate papillae
- foliate papillae

Front 10

Describe filiform papillae.

Back 10

- most numerous type

- slender, thread-like, project above tongue surface

- covered with cornified stratified squamous epithelium

- cats have large ones with two different prominences: caudal prominence is large and gives rise to caudally-directed, heavily cornified spine; supported by small, more rounded, rostral papilla with thin keratin covering.

Front 11

Describe conical papillae.

Back 11

- root of dorsal tongue in dogs, cats, pigs, ruminants

- larger than filiform papillae

- not heavily cornified

- ruminants have these on the inside of their cheeks as well (buccal papillae)

Front 12

Describe lenticular papillae.

Back 12

- only in ruminants

- flattened, lentil-shaped

- covered by stratified squamous epithelium; core of dense irregular CT

- found on torus linguae (prominence that is caudal to lingual fossa, cranial to root of tongue)

Front 13

Describe fungiform papillae.

Back 13

- scattered among filiform papillae

- domed/mushroom-shaped upper surface

- primary core of connective tissue

- secondary cores covered by non-cornified stratified squamous epithelium, with 1+ taste buds on upper surface (abundant in carnivores, goats; numerous in sheep, pigs; sparse in horses, cattle)

Front 14

Describe vallate or circumvallate papillae.

Back 14

- located on dorsum of tongue, rostral to root

- large, flattened

-may extend slightly above lingual surface

- completely surrounded by moat-like epithelium-lined sulcus

- epithelium lining side portion contains taste buds

- gustatory glands (serous) below sulcus, with ducts opening into sulcus at various levels

- mucus glands may be found beneath them, but secretory products emptied onto lingual surface

- horses/pigs have 1 pair, carnivores have 4-6 pairs, ruminants have 8-24 pairs

Front 15

Describe foliate papillae.

Back 15

- parallel folds of lingual mucosa on lateral margin of tongue just rostral to palatoglossal arch

- epithelium on the sides of the folds have taste buds, which open into the gustatory furrows that separate the papillae

- serous gustatory glands lie beneath furrows; ducts empty into furrows

- absent in ruminants; do not possess taste buds in cats (are rudimentary)

Front 16

Other than some papillae, where are taste buds found?

Back 16

- epithelium of soft palate, epiglottis, pharynx

Front 17

Describe components of a taste bud.

Back 17

- cluster of spindle-shaped specialized epithelial cells

- extend from basement membrane to taste pore (small opening in the epithelial surface in which it is embedded)

- 3 cell types:
- neuroepithelial cells: chemoreceptor or taste cells; cytoplasm contains vesicles adjacent to intraepithelial unmyelinated afferent nerve fibers

- supportive (sustentacular) cells

- basal cells: in basement membrane region; stem cells that regenerate the neuroepithelial and supportive cells (replaced every 10 days)

Front 18

What are the differences in the tonsillar surfaces of the domestic species?

Back 18

- dog and cat have smooth palatine tonsils

- lingual tonsils of horses/large ruminants/pigs and palatine tonsils of horses/small ruminants have tonsillar fossulae (deep surface invaginations)

Front 19

What are the differences in the epithelium covering generic tonsils in different regions?

Back 19

- oral cavity: covered by stratified squamous epithelium

- respiratory system: pseudostratified columnar

- intestine: simple columnar

Front 20

What are the two ways tonsils can be separated from surrounding tissue?

Back 20

- distinct connective tissue capsule (e.g. canine pharyngeal tonsil)

- slightly condensed connective tissue (e.g. Peyer's patches)

Front 21

What cells lie in the tonsils?

Back 21

- epithelium infiltrated with lymphocytes, leukocytes, particularly polymorphonuclear lymphocytes (PMLs)

- underlying epithelium: diffuse lymphoreticular tissue surrounding lymphatic nodules, which frequently have germinal centers and a cap of small lymphocytes and plasma cells adjacent to the epithelium

Front 22

Name the two types of teeth and which domestic animals they are found in.

Back 22

- brachydont: carnivores, humans, incisor teeth of ruminants, all except canine teeth of pigs

- hypsodont: horses, cheek teeth of ruminants, canine teeth of pigs (tusks)

Front 23

Describe brachydont teeth.

Back 23

- relatively short

- stop growing after eruption of tooth is complete

- have crown (enamel cap), neck, 1+ roots (covered with cementum) embedded in bony socket called dental alveolus

- exposed surface covered with enamel

Front 24

Describe hypsodont teeth.

Back 24

- longer than brachydont

- grow throughout adult life

- have elongated body, no crown or neck

- exposed surface covered with cementum

- boar tusks never develop roots

- in rodents, part of enamel-making apparatus is viable just below gumline: enamel constantly produced, provides sharp edge to incisors

Front 25

What does the term "masticatory mucosa" encompass? Describe it.

Back 25

- strongly-attached mucosa of hard palate and gingiva of maxillary and mandibular alveolar bone

- firmly attached to teeth and underlying alveolar bony tissue

- epithelium is parakeratotic stratified squamous (incomplete cornification- retains nucleus), with prominent epithelial rete pegs and dermal papillae (resistance to shearing forces)

- gingiva divided into attached gingiva and marginal (free, unattached) gingiva

Front 26

What is gingiva?

Back 26

- mucosa that has a propria-submucosa made up of dense irregular CT that is anchored directly to periosteum of alveolar bone of mandible and maxilla

Front 27

What are ameloblasts and odontoblasts?

Back 27

Ameloblasts: produce enamel

Odontoblasts: produce dentin

(Order of layers is ameloblasts, enamel, dentin, odontoblasts, dental pulp)

Front 28

What is the periodontal ligament?

Back 28

- densely packed collagen fibers

- attach teeth to the bony socket (dental alveolus)

- embedded in cementum of brachydont root/cementum of hypsodont anatomic crown and in the bone matrix (here called Sharpey's fibers)

Front 29

Describe components of the pharynx.

Back 29

- epithelial layer of oropharynx and laryngopharynx: stratified squamous, may be cornified in some species

- epithelium of nasopharynx: pseudostratified ciliated columnar

- minor pharyngeal salivary glands in propria-submucosa

- paired pharyngeal tonsils in some species

- tunica muscularis: striated skeletal muscle

Front 30

Name the major salivary glands.

Back 30

- parotid, mandibular, sublingual, zygomatic (carnivores), molar (cat)

Front 31

Name the minor salivary glands.

Back 31

- labial, lingual, buccal, palatine

Front 32

Describe serous acinar cells.

Back 32

- round, central nucleus

- vesicles (granules) in apical cytoplasm

- apical area is eosinophilic; basal area is basophilic (rER)

- pyramid- or wedge-shaped cells

Front 33

Describe mucous acinar cells.

Back 33

- irregularly-shaped, basal nucleus

- poorly staining cytoplasm (cell looks pale blue)

- no granules

Front 34

Describe mixed seromucous acini.

Back 34

- cells of both types normally interspersed

- serous demilune is fixation artifact: serous cells on outside, mucous cells on inside (next to duct)

Front 35

Describe duct hierarchy in salivary glands.

Back 35

- intercalated duct (from acinus): squamous epithelium

- striated duct: cuboidal to columnar; appear striated in basal area due to infolding of basal membrane and interposed mitochondria; nuclei closer to apex (near duct lumen)

- intralobular duct: cuboidal to columnar

- interlobular duct: pseudostratified columnar

- lobar duct: stratified columnar

- main duct

Front 36

What type of cell lies between secretory cells and basement membrane?

Back 36

Myoepithelial cells:

- modified epithelial cells with contractile properties

- thin cytoplasmic processes interposed between cells of the secretory unit, forming basket-like network, so contraction forces secretory product into duct system