11.4 Lab + Lecture Notes Flashcards
What are single-celled glands
- simplest glands
- Ex. goblet cells of the intestine
Compound acinar/tubuloacinar shaped glands are…
- always exocrine because implied apical lumen
- usually secrete via merocrine secretion
Salivary glands
- paired glands (undergo involution with aging)
- 3 major salivary glands ( Parotid, submandibular, sublingual)
- most easily distinguished by nature of secretion - all by merocrine process
- primary branches = excretory duct - sits outside of the gland
- secondary branches = striated duct
- tertiary branch = intercalated duct
Describe the secondary branch of the salivary gland
= striated duct
- simple columnar epithelium
- prominent basal striations
- FXN = ionic contant adjustment of fluid
Describe the tertiary branch of salivary gland
= intercalated duct
- located between striated and secretory acini
- low cuboidal eithelium
Describe the mixed seromucous acinus of the secretory glands and what is special about its appearance post preparation
- unique morphology due to artifact of standard preparations
= serous demilune (not seen in freeze-fracture prep.) = swelling of mucus cells causing serous cells to bulge out towards BM
What are zymogen granules
- stored proenzymes
- stain deeply eosinophilic
- use presence to help recognize the pancreas
Describe the successive morphologies in pancreatic branching morphogenesis
1) Pancreatic duct (excretory)
2) Interlobular ducts
3) Intralobular ducts
4) Intercalated duct (w/ centroacinar cells) - clear cytoplasm + low cuboidal shape
5) Secretory acini
Describe the centroacinar cells
- Unique ductal cell within the secretory acini of the pancreas
- represent the terminal extensions of the intercalated ducts
- morphology is like that of the duct = clear cytoplasm + low cuboidal cell shape
How does the mesonephric kidney tissue develop
= branching morphogenesis
How does the metanephric kidney tissue develop
- is induced by developing branches of the mesonephric tissue
Overview of branching morphogenesis
= alternating repeating patterns of growth + differentiation
1) induction of epithelial growth through interaction with other tissues
2) structural elaboration through successive pages of growth + branching
3) morphological differentiation of growing structures through altered gene expression
3 choices of glands
1) acinar = duct comes to point (won’t see lumen)
2) alveolar = spherical shpaed (ex. apocrine sweat gland)
3) tubular (like a test tube - eccrine sweat galnds)
Describe the branching morphogenesis of the lung
- gut tube endoderm –> trachea –> segmental bronchi –> bronchioles –> club cells of bronchioles –> alveoli
- steps:
1) trachea buds from endoderm (esophagus)
2) bronchi + bronchioles from branching
3) alveoli form through alteration of cells at tops of bronchioles
Describe the 5 stages of lunch development
1) Embryonic
- 0-8wks
- lung bud ot tertiary bronchi
- 1 proliferation (finite number of branches maybe only 3 generations + fetal mesenchyme but can see visceral pleura and lung body plan)
2) Pseudoglandular
- 6-16wks
- bronchial branching to 21 generations
- branching + proliferation
3) Canalicular
- 16-26 wks
- alveolar sacs begin
= morphogenesis
- most CT has been filled by bronchi or branches of pulmonary circulation
- individual cells start looking like squamous cells of alveoli
4) Saccular
- 26wks - birth
- alveolar sacs mature
-start seeing proper alveoli
- still have significant CT
5) Alveolar stage
- 32wks-8years
- alveolar sacs multiply (proliferation)
- most CT gone except largest bronchi - similar to adult lung
Describe the branching morphogenesis of salivary glands steps
1) bud forms from oral epithelium
2) elaboration creates branched ducts
3) specialized ductal cells accrue within lobes
4) secretory acini differentiate from tips of growing ducts
Describe the branching morphogenesis organization of the salivary glands
1) excretory ducts
- how saliva gets to mouth
-“trunk of tree”
2) interlobular ducts
- between lobules within surrounding CT
3) intralobular ducts
-within lobules
4) striated ducts
- prominent basal striations
- see invaginations of BM into membrane (ion pumps) allow adjustment of [ionic]
- in LM see v. thin lines of radially stretched mitochondria
5) Intercalacted ducts
- smaller in morphology
6) acinar cells
= secretory cells
Describe the branching morphogenesis organization of the pancreas
1) excretory ducts
- wirsung = major common duct
- santorini = small accessory duct
2) interlobular ducts
3) intralobular ducts
4) Intercalacted ducts
- bicarbonate adjustment
5) centroacinar cells
- bicarbonate secretion
- duct morphology in lumen of gland = cap of ductal portion of branch that sticks into lumen
= stem cells for secretory portion of the gland
6) acinar cells
= secretory cells - zymogen secretion
Describe the branching morphogenesis steps of the pancreas
I) doral + ventral buds from from gut endoderm (duodenum) then fuse
II) first “Trunk” creates ducts (santorini + wirsung (forms common bile duct with sphincter of oddi)
III) successive differentiation gets the intercalated ducts –> centroacinar cells –> pancreatic acini
Describe the endocrine pancreas embryology
- islets are derived from endoderm epithelium
- specifically in regions far from mesodermal tissue
- Zollinger-ellison syndrome = islet cell tumor of “G-cells” (gastrin producing)
Describe the branching morphogenesis of the mammary glands steps
1) modified sweat glands, initial growth stimulated by underlying fat pods
2)growth + branching of ducts specifies lobes + lobules of breast
3) ductal tip cells (“stem cells” for secretory acini)
= precursors to mamary gland acini
- important in some types of breast cancer
4) acinar elaboration occurs with pregnancy (and ductal elaboration)
Describe the branching morphogenesis organization of the mammary gland
A) lactiferous duct - trunk of tree - majro exocrine glands B) interlobular ducts - see dense CT forming breast stroma C) intralobular ducts - see loose CT - immediately around gland D) terminal ductules E) acinar cells (milk secretion) -milk only produced after pregnancy so acinar cells/terminal branching occurs in adulthood not embryology
Describe the branching morphogenesis organization of the kidney
A) ureters B) major + minor calyx C) collecting duct D) collecting tubule E) nephron - develops from unction by collecting tubule in surrounding mesenchymal tissue (metanephric tissue)
Describe the branching morphogenesis steps of the kidney
1) branches of mesonephric tubule (future ureter) create lobes of kidney
2) successive branching creates collecting ducts –> form the center of renal lobules
3) instead of acini the tips of each ductule induce surrounding mesenchyme to form second tubular strcuture
Describe the 5 specialization of branching morphogenesis highlighted in this class
1) Respiratory system
- conducting + respiratory airways
- alveoli (end branches_ inhibited from developing until end of embryogenesis
2) salivary glands
- parotid (pure serous)
- submandibular (seromucous, more serous)
- sublingual (seromucous, more mucous)
3) pancreas
- islets of langehans - separates from epithelium into CT
4) mammary glands
- adult morphogenesis
5) kidney
- collaboration of mesonephric + metanephric tissues
- collaboration fo different tissues forming discrete tubules
