Histology of the Endocrine Organs Flashcards
The exocrine pancreas is a compound tubuloalveolar serous gland that synthesizes and secretes digestive enzymes into the duodenum. What volume of the pancreas is this component?
98%
The pancreas has a head, neck, body, tail and capsule. Describe the structural components of the capsule. What are its contents? Is it stricty speaking a “capsule”?
»Loose connective tissue covers surface and extends deep into gland as septa, dividing organ into lobules
»Contains blood vessels, lymphatics, nerves and excretory ducts
»Not a capsule proper (would be dense CT with lots of collagen)
The acinus is the functional/secretory unit. Describe the shape and contents of acinar cells.
•Pyramidal serous cells
–Have narrow luminal surface and broad basal surface
–Water secretion
•Basophilic basal cytoplasm
•Acidophilic granules
–In apical cytoplasm, contain zymogens
•Basal nucleus with extensive rER and Golgi
•Apical tight junctions and microvilli
Intercalated ducts lead from the acinus, what cells are found here? Describe them.
–Centroacinar cells
•Squamous, weakly staining and agranular
What is the duct that drains the intercalated ducts into the main pancreatic duct, that is made of columnar epithelium?
Interlobar ducts
What are the functional/secretory units of the endocrine pancreas?
Islets of Langerhans
Islets of Langerhans appear as islands but are actually anastamosing irregular cords that vary in size from a few to hundreds of cells. Describe the cell shape, surroundings and staining.
–Cluster of weakly staining, polygonal cells surrounded by dark staining acini
»Fenestrated capillaries abundant
What do the arrows indicate?
Islets of Langerhans
What do the arrows indicate?
Alpha cells
What percent of the islets are alpha cells? Where are they located? What do they secrete?
–15-20% of islet
–Located at the periphery
–Glucagon secreting
What percent of islets are Beta cells? Where are they found in the islet? What do they secrete (primarily)?
–70%
–Core of islet
–Insulin secreting
What percent of the islet is comprised of delta cells? Where are they located in the islet? What do they primarily secrete?
–5-10%
–Located at the periphery
–Somatostatin secreting
What is the hypothalamohypophysial System comprised of?
–Endocrine and neuroendocrine components
Roughly what size is the hypophysis? What is another name for this? What kind of gland is it?
•Pituitary (Hypophysis)
–Pea sized
–Compound endocrine/neuroendocrine gland
Describe where the pituitary gland can be found.
•Located at the center of the base of the brain in a depression of the sphenoid bone called the sella turcica
What is the adenohypophysis made of? What are the three parts of it?
–Anterior lobe made of glandular epithelium
- Pars distalis
- pars intermedia
- pars tuberalis
What makes up the bulk of the anterior lobe of the adenohypophysis?
Pars Distalis
This abuts the pars distalis, and is sometimes referred to as the intermediate lobe. What is it?
Pars intermedia
What does the pars tuberalis form?
A sheath around the infundibulum
What is the neurohypophysis made of? What are its two parts?
–Posterior lobe made of neural secretory tissue
- Pars Nervosa
- Infundibulum
What is found in the pars nervosa?
•Neurosecretory axons and their endings
The infundibulum is a stalk existing between the pituitary and the hypothalamus. What does this give rise to? What does this contain, and what do the contents give rise to?
- Stalk existing between the pituitary and the hypothalamus
- Gives rise to the median eminence
- Contains the neurosecretory axons forming the hypothalamhypophyseal tracts
What are the components of the Hypothalamohypophyseal portal system?
- Superior hypophyseal arteries
- Hypophyseal portal veins
What do the superior hypophyseal arteries supply? What do they give rise to?
Supply superior structures including:
- Median eminence
- Infundibulum
- Pars tuberalis
–Give rise to primary capillary plexus
•Fenestrated capillaries
