Intro of glands

1. GLANDS
& CLASSIFICATION OF
EXOCRINE GLANDS
Dr. Aamir Shaheen
DPT (AIMC), M.Phil.
Lecturer, Quaid-e-Azam
Educational Complex,
Sahiwal

2. WHAT ARE GLANDS
The epithelial cells of the body which are
specialized to synthesize specific
substances which are released from
these cells onto an internal or external
surface. Such cells are called glandular
cells or gland cells.
An aggregation of gland cells into a
definite structure for the purpose of
secretion or excretion is called as a

4. CLASSIFICATION OF GLANDS
Generally glands are classified
into two major groups
1. Exocrine Glands
2. Endocrine Glands

7. EXOCRINE GLANDS
Those glands which release their
products onto an epithelial surface
either directly or through a duct.
e.g. Salivary Glands, Sebaceous
Glands

11. ENDOCRINE GLANDS
Those glands which release their products
directly into the blood stream.
e.g.
Pituitary Gland
Thyroid Gland etc.

15. EXOCRINE GLANDS

16. EXOCRINE GLANDS
Exocrine glands are sometimes made up
of single cell such as exocrine glands are
considered as unicellular glands. e.g. the
goblet cell which secrete mucus.
Most of the exocrine glands are made up
of many cells and are multicellular e.g.
sweat glands etc.

19. STRUCTURE OF EXOCRINE
GLANDS
Each exocrine gland has
1. Secretary portion
2. Non secretary duct or
system of ducts.

21. CLASSIFICATION OF EXOCRINE
GLANDS
1.On the basis of morphology of
duct/ducts and secretary portion
or portions
2.On the basis of nature of
secretary product.
3.On the basis of mode of
secretion

22. CLASSIFICATION ON THE BASIS OF
MORPHOLOGY
The exocrine glands can be classified on the basis of morphology
based upon two features
1.Morphology of duct or duct
system
2.Shape of secreting portion or
portions

23. PRINCIPLE
If the exocrine gland has single duct
or a single secretory passageway.
Such glands will be simple gland.
If the exocrine gland has a branched
duct system, such glands will be
called as a compound gland.

27. PRINCIPLE
If the secretory portion of the gland is in
the form of tubule. The gland is named as
tubular gland.
If the secretory portion of gland is in the
form of oval sac, such gland is named as
acinar or alveolar gland.
In some cases the secretory portion is
neither completely tubular nor acinar, but
combination of both, such glands are

30. CLASSIFICATION OF EXOCRINE
GLANDS
Taking into account above two
criteria, the exocrine glands are
classified and subclassified as
follows.
1.Simple glands
2.Compound glands

33. Simple glands
classification
Simple tubular glands
e.g. sweat glands,
endometrial glands of
uterus etc.
Simple acinar glands
e.g. sebaceous glands
of skin etc.

34. SWEAT GLAND

35. SEBACEOUS GLAND

36. COMPOUND GLANDS
If the duct of an exocrine gland
branches repeatedly, such glands are
named as compound glands

37. SUB-CLASSIFICATION OF
COMPOUND GLANDS
1. Compound tubular glands e.g.
brunner’s glands of duodenum.
2. Compound acinar glands e.g.
exocrine portion of pancreas.
3. Compound tubuloacinar glands e.g.
sub-mandibular salivary glands.

43. CLASSIFICATION ON THE BASIS OF
NATURE OF SECRETION
1.Mucous glands
2.Serous glands
3.Mixed glands

44. MUCOUS GLANDS
Those exocrine gland which produce a viscous,
slimy carbohydrate rich secretion named as
mucus. Such exocrine glands are named as
mucus glands.
e.g. pyloric glands of stomach.
The mucus cells secrete mucin, which is a
strongly hydrophilic glycoprotein. When
released it is hydrated and become viscus which
is known as mucus. It spreads over epithelial

46. SEROUS GLANDS
Those glands which produce a
thin watery and protein rich
secretion, such glands are serous
glands.
E.g. parotid salivary glands.

48. MIXED GLANDS
Those exocrine glands which produce
both mucus and serous secretion,
these are named as mixed glands. E.g.
sublingual and submandibular salivary
glands.

49. CLASSIFICATION ON THE BASIS OF
MODE OF SECRETION
Depending on the mode or
secretion, means the manner in
which secretion is modified, the
exocrine glands have 4
varieties.

50. CONTINUED…
Most of exocrine glands release
secretion which consists of
secretory product synthesized by
gland cells and no part of cell
cytoplasm is lost in the secretion.
In some of exocrine glands, a
portion or part of cell cytoplasm is

51. CLASSIFICATION ON THE BASIS OF
MODE OF SECRETION
1. Merocrine glands
2. Apocrine glands
3. Holocrine glands
4. Cytogenic glands

53. MEROCRINE GLANDS
If the secretory product is release
from gland cells without any loss of
cell cytoplasm. These glands are
called merocrine or eccrine glands.
Most of exocrine glands are of this
variety.
E.g. salivary glands, pancreatic

55. APOCRINE GLANDS
In these glands, a part of the apical
portion of cytoplasm is lost along with
secretory product. Such glands are
called as apocrine glands.
Examples: special sweat glands in
axilla, mammary glands.

57. HOLOCRINE GLANDS
Those glands in which entire cell
disintegrates with secretory product,
and all the cellular contents are
discharged from the gland as
secretion.
E.g. sebaceous glands of the skin,
meibomian glands of eyelids.

59. CYTOGENIC GLANDS
Those glands which produce
living cells are named as
cytogenic glands.
E.g. ovaries in females secrete
egg cell.

60. THANK YOU