EPITHELIUM AND GLANDS

052
EPITHELIUM AND
GLANDS
Dr. Larry Johnson

Objectives
• Identify every epithelium present in any tissue section.
• Differentiate between mucus and serous secreting
epithelia.
• Identify single-celled glands, endocrine glands and the
various types of exocrine glands.
• Detail the structure of the sebaceous gland.
• Identify the different types of sweat glands and distinguish
the duct from the secretory region.
• Identify myoepithelial cells and know their function.
From: Douglas P. Dohrman and TAMHSC Faculty 2012 Structure and Function of Human Organ Systems, Histology
Laboratory Manual

ORIGIN AND DISTRIBUTION OF
EPITHELIUM
ECTODERM - EPIDERMIS OF SKIN AND EPITHELIUM
OF CORNEA TOGETHER COVERS THE ENTIRE
SURFACE OF THE BODY; SEBACEOUS AND
MAMMARY GLANDS
ECTODERM
ENDODERM - ALIMENTARY TRACT,
LIVER, PANCREAS, GASTRIC
GLANDS, INTESTINAL GLANDS
• ENDOCRINE GLANDS - LOSE
CONNECTION WITH SURFACE
MESODERM
MESODERM
• ENDOTHELIUM - LINING OF BLOOD VESSELS
• MESOTHELIUM - LINING SEROUS CAVITIES
ENDODERM

Characteristics of epithelium
• Classification by # of layers
• Simple = single layer
• Stratified = multiple, stacked
layers
• Pseudostratified = appears to be
multiple layers, but all cells
touch basement membrane (all
cells do not necessarily reach
lumen)
• Classification by shape
• Squamous = flat
• Cuboidal = square
• Columnar = column

Laboratory Experience
• Identify and characterize various types of epithelia
• Recognize various glands and modes of secretion
• Recognize gland associated structures/cells and differentiate glands
from their ducts
• Understand significance of cytological expression of epithelial cells
with regard to function
053
Slide 53
Slide 35
Slide 93

Slide 33: Kidney (PAS/hematoxylin)
Periodic acid – Schiff
• Used to visualize: glycogen, glycoproteins, and glycosaminoglycans
• Steps in PAS staining
1. Periodic acid oxidizes 1,2-glycols to aldehydes
2. Schiff’s reagent colors the aldehyde groups (pink to magenta)
Brush border
Basement
membrane
The brush border is composed of
numerous microvilli which function
to increase surface area for
absorption of nutrient material and
fluid.
The structure on the brush border
that stains with periodic-acid Schiff
(PAS) stain is the glycocalyx.

EM 1 & 7
Slide 33
glycocalyx
PAS
staining
Lipid in SER
Observe various brush border - microvilli
The brush border is composed of numerous microvilli of a
uniform size projecting into a lumen. Each microvillus is
composed of microfilaments (actin) surrounded by the cell
membrane.

EM 2
Stereocilia of the epididymis - long thin microvilli
Stereocilia are very long, branched, non-motile microvilli of
differing lengths that function in absorption from the lumen.

EM 5 & 6
Observe cell junctions characteristic of epithelium

SPECIALIZATION OF EPITHELIA
MAINTAIN EXTENSIVE
CONTACTS AMONG CELLS
STRUCTURALLY AND
FUNCTIONALLY POLARIZED
JUNCTIONS
ZONULA OCCLUDENS - TIGHT
JUNCTION (BELT)
ZONULA ADHERENS –
ADHERING BELT
DESMOSOME (MACULA
ADHERENS) - SPOT ATTACHMENT
GAP JUNCTIONS - COMMUNICATION

Terminal bars
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Slide 32: Kidney (H&E)
Simple squamous
Simple cuboidal
Simple squamous
Simple cuboidal

Slide 75: Thyroid gland (endocrine)
Simple cuboidal epithelium
Basement membrane

SUMMARY OF TISSUE FEATURES OF
EPITHELIUM
• AVASCULAR
• EXTRANEOUS CELLS
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• REGENERATION
• MIGRATION

SUMMARY OF TISSUE FEATURES OF
EPITHELIUM
• AVASCULAR
• EXTRANEOUS CELLS
Slide 258
• REGENERATION
• MIGRATION
• METAPLASIA
• BASEMENT MEMBRANE

SECRETION – ACTIVE PROCESS
CONSUMING ENERGY
EXOCRINE GLANDS - DELIVER
THEIR SECRETION INTO
DUCTS OPENING INTO
EXTERNAL OR INTERNAL
SURFACE
ENDOCRINE GLANDS -
DUCTLESS, DELIVER THEIR
SECRETIONS INTO THE LYMPH
OR BLOOD STREAM
PANCREAS
has exocrine
PANCREAS
has endocrine

EXOCRINE GLANDS
DUCT
• SIMPLE - UNBRANCHED DUCT
• COMPOUND - BRANCHED DUCT
SECRETORY PORTION
• TUBULAR
• COILED TUBULAR
• BRANCHED TUBULAR
• ALVEOLAR
• BRANCHED ACINAR
• TUBULOACINAR
• TUBULOALVEOLAR
MUCUS VS SEROUS

TUBULAR
COILED TUBULAR
BRANCHED TUBULAR
ALVEOLAR
BRANCHED ACINAR
TUBULOACINAR
TUBULOALVEOLAR

ACINUS = FUNCTIONAL UNIT
072
Mucous - Light staining
Cytoplasm and dark, flattened
nucleus at base of cell
MUCOUS
SEROUS
072
Serous – dark red staining cytoplasm and
lighter, spherical nucleus

Slide 072: Submandibular gland
Simple columnar epithelia
Stratified columnar epithelia

Slide 072: Submandibular gland
Serous cells
Mucous cells
Serous demilune
The submandibular gland is a mixed (seromucous) gland whose mode of
secretion is merocrine secretion = exocytosis without loss of cellular components

MECHANISM FOR RELEASE OF
SECRETORY PRODUCTS
MEROCRINE SECRETION – EXOCYTOSIS W/O LOSS OF
SURFACE MEMBRANE
APOCRINE SECRETION – LOSS OF PART OF APICAL
CYTOPLASM AND SOME PLASMA MEMBRANE
HOLOCRINE SECRETION – RELEASE OF WHOLE cell
CYTOCRINE SECRETION –
MELANIN GRANULES
TRANSFERRED FROM
MELANOCYTE TO
KERATINOCYTES

MEROCRINE
APOCRINE

CYTOCRINE SECRETION - PASS MELANIN GRANULES
FROM MELANOCYTES TO KERATINOCYTES

Alternative slide 250
Slide 61: Terminal Ileum
Brush border composed of
microvilli
Microvilli are fingerlike
projections that greatly
increase the surface
area of certain cells to
help increase
absorption. Microvilli
are non-motile and are
composed of a core of
thin microfilaments
called actin.
Goblet cell releasing contents
Simple columnar epithelium

Alterative slide 242
Slide 40: Trachea
Goblet cell releasing
contents
Ciliated pseudostratified
columnar epithelium with
goblet cells
Note the thick basement membrane of the respiratory
pseudostratified columnar epithelium.
The main function of
cilia is to sweep or
move fluids, cells, or
particulate matter
across cell surface
in the lumen as to
remove dust in the
lungs. Microtubules
of the axoneme are
at the core of cilia
and make them
motile.

Slide 93: Epididymis
Pseudostratified columnar epithelium with stereocilia
Microvilli: small, non-motile projections composed of thin microfilaments
Stereocilia: long, non-motile projections (branched microvilli) composed of
thin microfilaments
Cilia: larger, long, motile projections composed of thick microtubules

Slide 35: Urinary bladder
Transitional epithelium
Specialized “dome-shaped”
cells
Basal cells

Slide 34: Ureter
Transitional
epithelium

Stratified squamous epithelium: the
protection epithelium
• Keratinized stratified squamous
(thick or thin)
• Prevent dessication
• Protect against abrasion
• Prevent foreign invasion
• Ex. Slide 29: Thick skin (ventral
surface of finger)
• Non-keratinized stratified
squamous
• Moist lubricated surface
• Ex. Slide 52: Tongue
Slide 029
Slide 52

Slide 52 : Tongue
Non-keratinized stratified
squamous epithelium
Mucous acini
Serous acini
Mucous cells stain light and serous cells stain dark.

Slide 53: Esophagus
Non-keratinized stratified squamous epithelium

Slide 29: Thick skin (ventral surface of finger)
Epidermis with
keratinized stratified
squamous epithelium
Dermis
Hypodermis
The major function of this type of epithelium (thick skin) is for
protection from mechanical stress, but it also prevents dehydration.

Slide 29 : Thick skin (ventral surface of
finger)
Keratinized stratified
squamous epithelium
Polyhedral cells
Cuboidal cells of the stratum
basale
The cells in the stratum
basale serve as stem
cells for the epidermis,
and their progeny
differentiate as they move
away from the base.

Slide 29 : Thick skin (ventral surface of
finger)
Duct of eccrine sweat
gland with stratified
cuboidal epithelium
Eccrine sweat gland
Myoepithelial cells
Myoepithelial cells are eosinophilic because of the presence of a
high density of contractile protein. These cells surround the gland
like a net and expel glandular secretions upon contraction.

Slide 31: Thin skin (scalp)
Sebaceous glands
The mode of secretion
used by sebaceous glands
is holocrine secretion
Keratinized, stratified
squamous epithelium

Slide 66: Recto-anal junction
Anus – stratified squamous
Rectum - simple columnar epithelium

Slide 66 : Recto-anal junction
Sebaceous glands
Apocrine sweat gland
Eccrine sweat gland

GLANDS OF EPIDERMAL ORIGIN
SWEAT GLANDS
• ECCRINE - COMMON
SWEAT GLAND -
LOCAL COOLING
• APOCRINE AXILLARY
REGION - FUNCTION
IN ANIMALS,
discharge in hair follicle

Epithelial tissues of the body
• Use table as guide
• Generalizations
• Entire GI system from gastroesophageal
junction to rectoanal
junction is lined by
simple columnar epithelium
• Cilia is present in most
respiratory passages

EPITHELIA ARE SPECIALIZED FOR
FUNCTIONS
ABSORPTION - INTESTINE
SECRETION - PANCREAS
TRANSPORT - EYE, ENDOTHELIUM IN VESSELS
EXCRETION - KIDNEY
PROTECTION – AGAINST
MECHANICAL
DAMAGE AND
DEHYDRATION
SENSORY RECEPTION –
PAIN TO AVOID
INJURY, TASTE BUDS,
OLFACTORY, ETC.
CONTRACTION –
MYOEPITHELIUM

SURFACE SPECIALIZATIONS OF
EPITHELIA
MICROVILLI - INTESTINE ABSORPTIVE CELL
CILIA - RESPIRATORY EPITHELIUM
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BASAL LAMINA – ALL
EPITHELIUM
038b
INTERCELLULAR CANALICULUS –
HEPATOCYTE
SECRETORY CANALICULUS –
GASTRIC PARIETAL CELL
FLAGELLA
33

SURFACE SPECIALIZATIONS OF EPITHELIA
INTERCELLULAR CANALICULUS –
HEPATOCYTE

SURFACE SPECIALIZATIONS OF EPITHELIA
SECRETORY CANALICULUS –
GASTRIC PARIETAL CELL

Clinical Correlation
Slide 38
Edward C. Klatt, M.D.
Mercer University School of Medicine
Normal larynx with ciliated
pseudostratified columnar epithelium
Abnormal larynx with stratified
squamous epithelium

Many illustrations in these VIBS Histology YouTube videos were modified
from the following books and sources: Many thanks to original sources!
• Bruce Alberts, et al. 1983. Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
• Bruce Alberts, et al. 1994. Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
• William J. Banks, 1981. Applied Veterinary Histology. Williams and Wilkins, Los Angeles, CA.
• Hans Elias, et al. 1978. Histology and Human Microanatomy. John Wiley and Sons, New York, NY.
• Don W. Fawcett. 1986. Bloom and Fawcett. A textbook of histology. W. B. Saunders Company, Philadelphia, PA.
• Don W. Fawcett. 1994. Bloom and Fawcett. A textbook of histology. Chapman and Hall, New York, NY.
• Arthur W. Ham and David H. Cormack. 1979. Histology. J. S. Lippincott Company, Philadelphia, PA.
• Luis C. Junqueira, et al. 1983. Basic Histology. Lange Medical Publications, Los Altos, CA.
• L. Carlos Junqueira, et al. 1995. Basic Histology. Appleton and Lange, Norwalk, CT.
• L.L. Langley, et al. 1974. Dynamic Anatomy and Physiology. McGraw-Hill Book Company, New York, NY.
• W.W. Tuttle and Byron A. Schottelius. 1969. Textbook of Physiology. The C. V. Mosby Company, St. Louis, MO.
• Leon Weiss. 1977. Histology Cell and Tissue Biology. Elsevier Biomedical, New York, NY.
• Leon Weiss and Roy O. Greep. 1977. Histology. McGraw-Hill Book Company, New York, NY.
• Nature (http://www.nature.com), Vol. 414:88,2001.
• A.L. Mescher 2013 Junqueira’s Basis Histology text and atlas, 13 th ed. McGraw
• Douglas P. Dohrman and TAMHSC Faculty 2012 Structure and Function of Human Organ Systems, Histology Laboratory
Manual - Slide selections were largely based on this manual for first year medical students at TAMHSC

The End!