1. Introduction Types of glands Classification Functions of glands
GLANDULAR EPITHELIUM
Introduction
Types of glands
Classification
Functions of glands

2. Introduction: Glands are derivatives of surface epithelium.
Cells from mother epithelium invaginate the connective tissue beneath then develop the gland
If the connection between the two
persists, exocrine gland forms.
The connection is the duct of the gland
If the connection obliterates,
endocrine gland forms.

3. TYPES OF GLANDS (Classification)
There are the following groups:
Exocrine glands:
Pass secretions through a duct system to a body surface
Secretions are normally enzymes
2. Endocrine glands:
Pass secretion directly into blood or lymph (internal secretion)
Secretions are normally hormones
3. Mixed glands: These have both exocrine and endocrine components.

4. Types of Exocrine glands
a. According to the number of secreting cells
unicellular glands – a single cell is a
complete gland. Good example is a
Goblet cell (mucous cell).
Multicellular glands – each gland is formed
by more than one cell, examples are
Parotid (salivary) glands and Pancreas.

5. Holocrine. whole cell dies, the discharges go
Exocrine gland
b. According to the mode of secretion
Holocrine. whole cell dies, the discharges go
together with the cellular contents
(remnants of a dead cell)
eg. sebaceous and tarsal gland cells.

6. Apocrine. (membrane budding) Products
Exocrine gland
Apocrine. (membrane budding) Products
accumulate at the apical part of the cell then
discharges its apical cytoplasm
eg mammary gland cells.

7. Merocrine. Only cell products are discharged
Exocrine gland
Merocrine. Only cell products are discharged
eg sweat gland cells.
Cytogenous. A product is a complete living
cell. eg gonads (testes and ovaries)

8. Simple glands. All cells discharge to single duct
Types cont……….
c. According to the shape of secreting units:
Simple glands. All cells discharge to single duct
tubular – tube like unit. May be straight or coiled
tails.
saccular/alveolar/acinus – pocket like unit
simple tubular straight / coiled

9. Compound glands. Several single units share a common discharging duct.
Types cont……….
Compound glands. Several single units share a
common discharging duct.
compound tubular
Compound saccular/alveolar
Compound tubulo-alveolar
Compound saccular

10. Compound glands

11. EXOCRINE GLANDS SIMPLE COMPOUND TUBULAR SACCULAR Or ALVEOLAR TUBULAR
Secreting units….. .
EXOCRINE GLANDS
SIMPLE
COMPOUND
TUBULAR
SACCULAR Or
ALVEOLAR
TUBULAR
SACCULAR Or
ALVEOLAR
TUBULOALVEORAL
TUBULAR coiled
TUBULAR straight

12. d. According to the nature of secretions:
Types cont……….
d. According to the nature of secretions:
Serous glands. Waterly secretions
Mucous glands. Mucoid or mucin
secretions
Seromucous glands. Mixed serous and
mucous secretions

13. Endocrine glands cells).
Unicellular - (rare-known. example – enteroendocrine
cells).
Multicellular with the cells surrounded by the conn. Tissue
capsule sending inward septae into unit
structures.
TYPES are:
a. According to the cell arrangement (grouping):
i. cord and clump gland – cells are arranged like a bunch
of grapes.
ii. Follicle gland - cells are circularly arranged with a
central lumen.
iii. Scattered masses – aggregated cells housed in an
organ . .

14. b. According to secretion storage site:
Endocrine……
b. According to secretion storage site:
i. intracellular – secretions are stored inside
the cell prior discharge.
ii. Extracellular – secretions are stored
outside the cell prior discharge

15. Functions of glands ( Exocrine/endocrine)
1. Secretion.
Exocrine glands secret watery and enzyme
components.
Endocrine glands secret hormones.
2. Storage of secretory materials.
3. Protection.
4. Absorption.