Histological Organisation of Oral Cavity and Salivary Glands Flashcards
masticatory mucosa
(a) location within the oral cavity
(b) organisation of its epithelium
(c) organisation of its lamina propria
(a) hard palate, dorsum of the tongue, gingivae
(b) keratinized or parakeratinized stratified squamous epithelium. The keratinized epithelium consists of four layers: basal layer, spinous layer, granular layer and cornified layer. The parakeratinized epithelium is similar histologically to that of the keratinized epithelium except that the cells in the stratum corneum retain their nuclei. The junction between teh epithelium and lamina propria is characterized by numerous long deep papillary proections/ridges intothe connective tissue [known as rete pegs].
(c) The lamina propria of the masticatory mucosa is directly attached to the periosteum of the underlying palatal or alveolar bone, with no intervening submucosa. This arrangement is referred to as the mucoperiosteum .
lining mucosa
(a) location within the oral cavity
(b) organisation of its epithelium
(c) organisation of its submucosa
(a) lips, cheeks, floor of the mouth, undersurface of the tongue and the soft palate
(b) The epithelium of the lining mucosa is non-keratinized and has three layers: basal layer, intermediate (similar to spinous layer) and a superficial layer. The underlying lamina propria is separated from the epithelium by a basement membrane.
(c) A submucosa is present in most regions of the oral cavity covered by th elining mucosa with the exception of the undersurface of the tongue. In the lips and cheeks, the submucosa comprises of collagen and elastic fibres that bind the mucosato the underlying muscle and salivary glands.
Discuss the vermilion zone of the lip.
[what is it and what gives it its red color]
The vermilion zone represents a transitional zone between keratinized epithelium of skin and the non-keratinzed epithelium of lining mucosa. It is a very thin keratinized epithelium that contains no adnexal skin structures [though in some populations it may contain sebaceous glands].
The vermilion zone is red because:
1. Epithelium is thin
2. Epithelium contains eleidin which is transparent
3. Blood vessels are present near the surface
[Eleidin is a semi-fluid clear substance present in the stratum lucidum of the skin epithelium.]
Discuss filiform and foliate papillae.
(a) Filiform papillae
✓ most numerous and smallest papillae
✓ They provide the tongue a rough surface to aid in manipulation and food processing. They consist of a connective tissue core covered by a stratified squamous keratinized epithelium.
✓ They have a tapering end that is directed backwards.
✓ They are distributed on the entire dorsum of the tongue and contain no taste bud.
(b) Foliate papillae
These are not well-developed in humans.
Discuss fungiform and circumvallate papillae.
(a) Fungiform papillae
✓ mushroom-shaped papillae that occur singly and evenly spaced in between the filiform papillae over the dorsum of the tongue
✓ are more numerous at the tip of the tongue
✓ they appear as red spots
✓ epithelium that covers them is slightly thinner than that on the other parts of the tongue
(b) Circumvallate papillae
✓ 8-12 in number and located just anterior to the V-shaped groove (sulcus terminalis)
✓ largest papillae
✓ a deep trench formed by infolding of the epithelium surrounds each one of them
✓ The core of each circumvallate papilla consists of connective tissue covered by a stratified squamous epithelium.
✓ The epithelium that forms both the walls of the trench contains numerous taste buds
✓ Ducts of excretory lingual glands open into the bottom of the trench. These are known as Von Ebner’s glands that are serous in nature. They also secrete the enzyme, lingual lipase that begins the process of lipid hydrolysis in the mouth.
[Virtual microscope]: circumvallate papillae
Click on Answer to view histological images of the epiglottis.
Click on Answer to view histological slides of the tooth.
Click on Answer to view histological slides of the parotid gland.
[Slide 1] [Slide 2] [Virtual microscope]
Things to note:
The parotid gland is almost entirely comprised of serous acini.
Connective tissue septae between the lobules carry blood vessels and nerves. An outer capsule envelops the gland.
The large ducts between the lobules are lined by a two-cell layer epithelium.
The larger ducts appear striated. This is due to membrane specializations in the form of interdigitations at the bases of the cells, and adaptation for ion transport.
Observe how the secretory acini are made of a single layer of purplish, basophilic cells whose boundaries are not clear.
Observe the interlobular ducts wiht obvious lumens and acidophilic nature.
Click on Answer to view histological slides of the submandibular gland.
