Case 3 Histology Flashcards
(34 cards)
what do the secretory units of the salivary glands consist of?
a branched tubule-acinar structure
Compound tubuloacinar glands
- Branching duct system (number of ducts that interconnect)
- Secretory component – tubular (elongated) and acinar (grape-shaped)
(you have ducts and then coming of this you have tubular-shaped glands and grape-shaped glands)
what do the acinar cells produce?
either serous, mucous or a mixed saliva
in some cases, what do the serous cells form?
caps around the mucous secreting acini = serous demilunes
which cells stain darker, serous or mucous secreting cells?
cells which produce serous saliva stain much darker with H&E stain compared to mucous secreting cells
what is the route of saliva from the acini cells? epithelium?
the acini cells secrete saliva into small intercalated ducts which, in turn, drain into large striated ducts and then into even larger excretory ducts
EXCRETORY DUCTS
Series of ducts that increase in size
- Intercalated ducts – small, tiny lumen – simple low cuboidal epithelium (look bit flatter than square shaped (because low) but not like squamous epithelium)
- Striated ducts – formed by merging intercalated ducts – simple columnar epithelium (appears striped on high magnification)
- Intralobular ducts – formed by merging striated ducts – gradually increase in size and become surrounded by CT (big collections of lobules make a lobe) (as ducts get bigger, they get more CT around them – more support)
- Interlobular ducts – epithelium may be pseudostratified
- Interlobar ducts – may possess cilia – may be stratified or pseudostratified – epithelium eventually convey saliva into oral cavity (e.g. submandibular duct)
what surrounds the parotid gland? what does this form? what seen here?
- Surrounded by a (dense) connective tissue capsule
- Septa extend from the capsule into the gland (white & pink), dividing it into lobules (glandular tissue is lobulated)
- Blood vessels (simple squamous epithelium is a sign it’s a blood vessel), nerves and excretory ducts (enlarged ones) (stratified/pseudostratified columnar epithelium is a sign of this) can be seen running through the septa
what type of saliva do parotid glands produce?
- serous saliva
- therefore the secretory units are stained quite dark (likely to be parotid if consistent dark staining)
what do the serous-secreting acini cells look like?
- serous cells tend to be pyramidal in shape, with their broad base on the basement membrane and their narrow apical surface facing the lumen
- their nuclei are round in shape and the lumina of the acini tend to be very small
- (clusters of dark cells also secrete into one lumen in the middle)
what may you be able to find inside the basal lamina surrounding the base of the serous cell in parotid gland?
- myoepithelial cells
- these cells have a flattened nucleus
- they are contractile and help to expel the secretory product
what will you see amongst the acini cells in the parotid gland?
- small intercalated ducts – the cells of these ducts are cuboidal in shape and their nuclei round
- you may also see striated ducts – the cells are columnar in shape and the cytoplasm may appear to be striated
- (intralobular duct or striated duct if got quite tall cells)
what can be seen in the dense irregular connective tissue of the septa in the parotid gland?
- blood vessels (muscle tissue can look quite similar to the simple squamous on the inside of lumen – therefore don’t assume that appears thick isn’t a blood vessel) and nerves
- excretory ducts can be seen within the septa – the cells of these ducts may be stratified or pseudostratified cuboidal or, as they increase in size, stratified columnar (tall cells and look like lots of nuclei)
what surrounds the submandibular gland? what does this form? what seen here? what acinar cells like? what mucous cells look like?
- Like the parotid gland, this gland is surrounded by a connective tissue capsule
- Septa extend from the capsule into the gland, dividing it into lobules
- Blood vessels, nerves and excretory ducts can be seen running through the septa
- Acinar cells – round nuclei (normally associated with cuboidal cells) – some transitioning but probably low cuboidal epithelium
- Mucous acinar appears paler – only around the edge and nuclei around edge appear dark
what type of saliva does the submandibular gland secrete?
- mixed gland with both mucous and serous secreting cells – the serous cells predominate
- some secretory units stain darkly and are totally serous secreting cells
- it is also possible to find many pale stained acini; these mucous secreting cells are capped by darkly stained serous demilunes
- (find in submandibular and sublingual glands) (sublingual glands, because they are more mucous than serous, they tend to have more demilunes in their serous component rather than whole serous acini)
- paler because mixed gland however you can’t just say it’s paler without comparing them both on same slide
what type of saliva does the sublingual gland secrete?
seromucous (mainly mucous – eat your snot with tongue)
where do the ducts of the salivary glands open into the oral cavity?
a slight fold called a sublingual papilla, from which the ducts of the submandibular salivary glands open.
???
- parotid -> cheek
- submandibular -> floor of mouth
- sublingual -> under tongue
innervation of the salivary glands?
chorda tympani (facial nerve) -> submandibular ganglion -> sublingual & submandibular glands glossopharyngeal nerve -> otic ganglion -> parotid gland
what is the pancreas surrounded by? what does this form? what found here?
- thin connective tissue capsule
- septa extend into the gland from the capsule, separating the pancreatic lobules
- the connective tissue septa that divide the gland into lobules are obvious
- septa - the connective tissue varies from loose irregular to areas of dense irregular
- blood vessels (simple squamous epithelium – can appear more squished), nerves and interlobular ducts are present in the septa
describe the exocrine component of the pancreas
- The exocrine component of the gland is similar to the parotid gland
- It consists of closely packed secretory acini which drain into a duct system
- The smallest intercalated ducts drain into intralobular ducts which, in turn, drain into interlobular ducts
- The interlobular ducts are located in the septa of the gland
- The interlobular ducts drain into either the main pancreatic duct or the accessory pancreatic duct
describe the endocrine component of the pancreas
- The endocrine component of the gland is comprised of clusters of cells known as the pancreatic islets (islets of Langerhans)
- These are scattered throughout the gland but are most numerous in the tail
- The islets vary in size and are composed of a number of different cell types, each of which is responsible for secreting one type of hormone
- Cells not going to be in a circle like the acini – nuclei don’t make a circle – they are scattered about
are the acini and islets stained dark or pale?
- acini = dark
- scattered through the glandular tissue there are a few pale-stained spheres = islets (not significantly lighter)
describe the acini
- cells of acini
- what supported by
- ducts - epithelium
- The cells of the acini are triangular in shape with their apex directed towards a very small lumen
- Their nuclei are basally located
- They are supported by a fine reticular network containing a rich capillary network
- Almost like a ring of pearls – in the middle would be a lumen – very small so might not be able to see it or might not have cut through the lumen
- The intercalated and intralobular ducts are formed from simple cuboidal epithelium
- interlobular = simple/stratified cuboidal/columnar (as you move along, they get taller and more stratified)
- main pancreatic ducts – tall columnar
is it possible to distinguish between the different cells types of islets?
not using H&E stain
what are the islets cells supported by?
fine network of collagen fibres
what are the interlobular ducts encircled by? what are they lined with?
- encircled by a layer of dense irregular connective tissue which provides support to the duct and the gland
- lined with stratified cuboidal/columnar epithelium
- ducts – very tall columnar cells, fuzzy edge (could be some cilia), nuclei make it look stratified or pseudostratified – nuclei are all near the bottom
- around it organised and dense connective tissue
- ducts can be quite large
