Meghan Barboza, PhD
Online Course
Glands: Specialization of Epithelia for Secretion
Glandular Development
http://medicinembbs.blogspot.com/2011/09/epithelium.html
http://medicinembbs.blogspot.com/2011/09/epithelium.html
Classification Is Based On:
 Secrete to blood – or - not
 Endocrine
 Exocrine
Exocrine Pancreas
Islets of Langerhans
Classification Is Based On:
 Secrete to blood
 Endocrine

Release hormones
into bloodstream
 or not
 Exocrine
 Secrete products
to a free surface
Further Classification of Exocrine
Glands:
 Number of cells
 Shape
 A single duct or a system of ducts
 Type of secretory product
 Mode of secretion
Number of Cells
 Unicellular
 Goblet cell
http://medicinembbs.blogspot.com/2011/
09/epithelium.html
Multicellular Glands
 Most glands are not
unicellular and so further
classification is needed:
stomach
 Sheets of secretory cells

Note nuclei
Multicellular Glands:Adenomere
 Discrete secretory
entities
 Adenomere
Discrete Secretory Entities: Adenomere
Round
 Acinar
(Alveolar)
 Branched
Discrete Secretory Entities: Adenomere
 Tubular
 Coiled
 Straight
 Branched
Simple Tubular
Large Intestine
Simple Coiled
Skin -Sweat Gland
Simple branched tubular
Small Intestine
Simple branched acinar
Skin – Sebaceous Gl.
Compound Glands: more than one duct
Compound Tubular
Esophagus
Compound Tubuloacinar
Salivary Gland
Compound Acinar (Alveolar)
Pancreas
Compound glands: Stromal and
Parenchymal Subunits
 Parenchyma
 Functional
part
 Stroma
 Support
 Provides
structure
Classification of Exocrine Glands
Number of cells
Shape
A single duct or a system of ducts
Type of secretory product
Mode of secretion
Serous
Mucous
Mucous plus Serous = “Mixed”
Classification of Exocrine Glands
 Number of cells
 Shape
 A single duct or a system of ducts
 Type of secretory product
 Mode of secretion
 Merocrine
 Apocrine
 Holocrine
Mode of Secretion
 Merocrine – Most Common
 Secretion through exocytosis
 No damage to or loss
of gland
Mode of Secretion
 Apocrine
 A portion of the
cell cytoplasm
and cell
membrane
buds off with
the secretory
material
Apocrine Sweat Glands
Wikipedia commons
Mode of Secretion
 Holocrine
 The entire
secretory
cells
bursts and
is secreted
 Most
damaging
Sebaceous Gland
Further Classification of Exocrine
Glands: Summary
 Number of cells
 Unicellular vs multicellular
 Shape
 Sheet
 Acinar/alveolar
 Tubular
 A single duct or a system of ducts
 Simple
 Compound
 Type of secretory product
 Mucous
 Serous
 mixed
 Mode of secretion
 Merocrine
 Apocrine
 Holocrine
Check your understanding
 Why do glands have a basement membrane?
 Describe a gland that is mixed, compound
tubuloacinar.
 Is it possible to have a gland that is tubuloacinar
and simple? Why or why not?
 Which of the following gland types would extrude
the most complex secretions: mixed simple
coiled tubular, serous compound tubuloacinar, or
mucous simple branched?