Epithelial Glands I

Question 1

Types of Gland Based on Development

Answer 1

• Glandular tissue is composed of epithelial cells specialized for a secretory function
• Secretory cells may remain incorporated within the epithelial layer(unicellular glands) or may grow down into there underlying connective tissue(multicellular glands)
• Epithelial down growth may remain conected to the epithelial layer from which it orgiinated:
  
  • This gives rise to an exocrine gland
  • Exocrine glands include salivary glands, mammary glands , sweat galnds , sebaceous gland, liver and pancreas
  • This type of gland secretes its product via a duct derived from the original connection to the epithelial layer

Question 2

What happens if the epithelial down growth degenerates?

Answer 2

• If hte epithelial down growth degerantes then this leaves the secretory tissue isolated from its parent epithelial layer:
  
  • Gives rise to an endocrine gland
  • Endocrine glands include pituitary,thyroid , pineal , parathyroids, adrenals, gonads,liver and pancreas
  • Type of glands secretes its product( a hormone) into surrounding blood vessels

Question 3

Exocrine glands

Answer 3

• Exocrine glands are epithelial outgrowths into underlying connective tissue that retain their connection to the overlying epithelium in the form of one or more ducts

Question 4

Endocrine glands

Answer 4

• Endocrine glands are epithelial outgrowths into underlying connective tissue that lose their connection to the overlying epithelium
• These glands lack ducts and must secrete their prouct(hormone directly into surrounding blood vessels

Question 5

Exocrine

Endocrine

Answer 5

• Secretory product is transported via a duct system(usually) to the lumen or surface of an organ

Endocrine:

Secretory product hormone is released directly into blood in the absence of a duct

Question 6

Paracrine

Autocrine

Answer 6

• Secretion affects neighboring cells
• Example:growth factors

Autocrine:

• Secretion affects the cell that released the secretory product
• Example:IL-2 secreted by T cells

Question 7

What are ways to classify glands

Answer 7

• Based on number of cells comprising the gland
• Based on absence or precence of ductal branching
• Based on shape of secretory portion

Question 8

Cells comprising the gland and breakdown

Answer 8

• Unicellular:
  
  • Examples:
    
    • Golbet cells of intestine and trachea(exocrine)
    • Mucous cells of stomach(exocrine)
    • Enteroendocrine cells(endocrine)
• Multicellular
  
  • Examples:
    
    • Include most other endocrine and exocrine glands

Question 9

Based on absence or presence of ductal branching

Answer 9

• Simple multicellualr glands do not exhibit ductal branching
• compound multicellular glands have ductal branching

Question 10

Based on shape of secretory portion

Answer 10

• Tubular:
  
  • Straigh:crypts of Lierberkuhn in large intestine
  • Coiled: sweat glands of skin
  • Branched:fundic,pyloric, and cardiac glands of stomach
• Alveolar(Acinar)
  
  • Meibomian glands of eyelid
  • Sebaceous glands of skin
• Tubuloalveolar(-acinar)
  
  • Salivary glands
  • Brunner’s glands of duodenum
  • Mucous glands of esophagus

Question 11

Simple excretory duct:

Answer 11

• Secretory portion
  
  • Tubular
  • Coiled
  • Tubular branched
  • Acinar/alveolar:

Question 12

Compound(branched) excretory duct:

Answer 12

• Secretory portion:
  
  • Branched tubular
  • Branched alveolar(acinar)
  • branched tubuloalveolar (-acinar)

Question 13

Glands classified by type of secretion

Answer 13

• Serous:
  
  • watery,enzyme filled secretion
  • example:parotid salivary gland
• Mucous:
  
  • Thick, mucin-containing secretion
• Mixed(serous-mucous):
  
  • Secretion is a combination of serous and mucous
  • Acinus is typically mostly mucous capped by a half moon shaped group of serous cells forming a serous demilune
  • Example:submandibular and sublingual glands

Question 14

Type of gland by mechanism of secretion:

Answer 14

• Merocrine(eccrine):
  
  • Secretory product is typically stored in membrane bound vesicles, and cytoplasm/cell membrane is retrieved in an exoctyosis/endocytosis cycle
  • include most glands
• Apocrine
  
  • Apical cytoplasm is released along with secretory product
  • Example:axillary sweat glands
• Holocrine
  
  • Entire cell is released as aprt of secretory product
  • Example:sebacous glands

Question 15

Answer 15

Sebaceous glands 100x

Question 16

Submandibular gland:

Answer 16

• Both serous and muous cells
• Serous cells form serous demilune capping mucous acini
• myoepithelial cells surround acini

Question 17

Sublingual gland

Answer 17

• Mucous acini(pale in appearance)(PAS+)
• Flattened nuclei at basal poles of cells myoepithelial cells surround acini

Question 18

Parotid Gland:

Answer 18

• Serious acini
• Apical regions contain zymogen granules
• RER predominates in basal regions of secretory cells

Question 19

Answer 19

Sublingual Gland 100x

Question 20

Answer 20

Parotid gland 100x

Question 21

Answer 21

Submandibular Gland