1 HISTOLOGY LAB EPIHELIUM TISSUE 02/15/2021

EPITHELIUM • LATERAL DOMAIN

o Close contact with neighboring cells
- Cells (specialized functions) → tissues
o Made up of different types of
- Tissues
junction which allow cell to cell
o Epithelium – covers body surfaces, lines
communication
cavities and forms glands; perform
o Allows the epithelium to be in close
secretion
contact with its neighboring cells
o Connective – underlies supports the
other 3 basic tissues both structurally
and functionally
o Muscular – made up of contractile cells
that is responsible for movement
production
o Nervous Tissue – receives,, transmits
and integrates information from outside
and inside the body in order to control
the activities of the body
- cover the external surfaces of the body, line the
internal cavities, form various organs and glands
and line the ducts - Basement membrane is a structure that is going
- Differs from organ to organ to separate the surface of the epithelium with the
o Depends on location and function underlying connective tissue
▪ Columnar = absorption - Semipermeable
▪ Cuboidal = secretion - Basement membrane and Basal lamina are
▪ Squamous = protection quite used interchangeably
- Basement membrane has 2 portions
Epithelium: CHARACTERISTICS 1. Basal lamina – in contact w/
1. Closely apposed cells – little extracellular epithelium
material between cells 2. Reticular lamina – in contact w/
- Communication is still possible because connective tissue
they are joined by specialized cell to cell - Staining can affect the appearance of basement
junctions membrane
- These junctions allow some structrues in o Hematoxylin & Eosin – not going to have
the apical surface to be within that particular a good effect for the visualization of
surface only, others allow communication in basement membranes;
between cells and others ae responsible fot o Periodic acid schiff (PAS) – has high
the attachment of the cell to the basement affinity to the sugar molecules that is
membrane found in the basement membrane;
2. Functional and morphological polarity appear magenta so it is going to be
• APICAL DOMAIN easily distinguish under the light
o exposed at the body surface or at
lumen of the body cavity, duct, tube
or vessel
o always directed toward the exterior
surface or lumen of an enclosed
cavity
• BASAL DOMAIN
o rests on a basement membrane
o resting of the epithelium to the
basement membrane
▪ Basement membrane: non-
living adhesive material
secreted by the epithelium Different staining methods appliead
and the underlying a. H & E – cannot easily identify the basement
connective tissue membrane; cannot see goblet cells
▪ Between the connective and b. PAS – easily distinguished; see goblet cells
epithelium
 2 HISTOLOGY LAB EPIHELIUM TISSUE 02/15/2021

3. different organs exhibit special membrane

modification on apical surface
• CILIA
- motile, found on uterine tubes and
conducting tubes of the respiratory system
(trachea &b bronchiole tree)
- where goblet cells are placed
- going to move in a sweeping motion so that
whatever foreign bodies that is trapped
during inhalation will be stuck in the mucus
and the cilia is going to move it upwards
toward the oral cavity
• MICROVILLI
- small, non-motile projections that line all
absorptive cells in the small intestine and
proximal convoluted tubules in the kidney
- visible Number of cells
- described as brush border A. Simple – single layer
• STEREOCILIA B. Stratified – 2 or more layer
- long, non-motile, branched microvilli that
line cells in epididymis and vas deferens Morphology (surface of the cell)
- also found in the sensory hair cells in the A. Squamous – thin & flat
inner ear function which performs as B. Cuboidal – square like
Mechanoreceptors C. Columnar – tall & wider cells

SIMPLE SQUAMOUS
Classification Locations Major
functions
Simple Vascular Exchange,
squamous system barrier in central
nervous system
Body cavities Exchange (gas)
(mesothelium)
Bowman’s Lubrication
capsule (kidney)
Respiratory Barrier
spaced in lung
4. Avascular With is greater than the height
- no blood vessels within the layer Lines the blood vessels
- oxygen, nutrients and other metabolites Blood air barrier – area where in change of gas takes
diffuse from the blood vessels in the place
underlying connective tissues to the
epithelium
- the substances is going to diffuse from the
connective tissue towards the basement
membrane until it reached the epithelial
cells
5. Frequent cell division
- exposed to wear and tear injury, needs
replacement
- Performs lots of mitosis
 3 HISTOLOGY LAB EPIHELIUM TISSUE 02/15/2021

SIMPLE CUBOIDAL
Classification Locations Major function
Simple cuboidal Small ducts of Absorption
exocrine glands
Surface of ovary Barrier
(germinal
epithelium)
Kidney tubules Secretion
Thyroid follicles Conduit
Width, depth and height are approximately the same STRATIFIED CUBOIDAL
Spherical nuclei
Classification Locations Major function
Stratified Ducts of sweat Barrier
cuboidal glands
Large ducts of Conduit
exocrine glands
Anorectal
junction

SIMPLE COLUMNAR
Classification Locations Major
functions
Simple Small intestine Absorption
columnar and colon
Stomach lining Secretion
and gastric
glands STRATIFIED COLUMNAR
Gallbladder Classification Locations Major function
Elongated nuclei Stratified Largest ducts of Barrier
columnar exocrine glands
Anorectal Conduit
junction

STRATIFIED SQUAMOUS
Classification Some typical Major
location functions
Stratified Epidermis Barrier PSEUDOSTRATIFIED COLUMNAR
squamous
Classification Locations Major function
Oral cavity and Protection
Pseudostratified Trachea Secretion
esophagus
columnar
Vagina
Bronchial tree Absorption
Ductus deferens Conduit
Keratinized – epidermis Efferent
Non-keratinized – oral cavity, esophagus, vagina ductules of
Keratin – protective protein that aids in the avoidance epididymis
the secretion or drying Mainly ciliated
Pseudostratified ciliated columnar epithelium
 4 HISTOLOGY LAB EPIHELIUM TISSUE 02/15/2021

EXOCRINE EPITHELIAL GLANDS

1. Unicellular
- Goblet cells (Trachea epithelium; absorptive
cells)
- Mucin and Mucus – trap foreign materials;
passage- large intestine; protection -
stoamch
2. Multicellular
TRANSITIONAL EPITHELIUM
- Salivary Glands
Classification Locations Major function
o Merocrine gland
Transitional Renal calyces Barrier
▪ Secretor product is
(urothelium)
delivered in membrane-
Ureters Distensible
property bound vesicles
Bladder ▪ most common
Urethra mechanism of secretion
▪ pancreatic acinar cells
- Sebaceous glands
o Holocrine gland
▪ Secretory product
accumulates within the
maturing cell which
simultaneously
undergoes programmed
cell death (Apoptosis)
▪ High mitotic activity
Filled – flatten
- Mammary glands
Empty – normal state/resting state (dome like)
o Apocrine gland
▪ Secretory product is
released in the apical
portion of the cell
(Detach surface) –
surrounded by a thin
layer of cytoplasm with
an envelope of the
plasma membrane
▪ Apocrine glands of the
Right = empty; dome like
skin; glands of the
Left = filled; flat
eyelid; ceruminous
glands
GLANDULAR EPITHELIUM
- Epithelium that comprises the glands
- Characteristics – “Secretes” a product
(carbs, proteins, lipids)
Endocrine Glands
o Internal secretion
o Hormones
o “Ductless”
o Pituitary, Thyroid, Testes, Ovaries
o Release its secretions via capillary network
o Products released via blood stream
Exocrine Glands
o Secretes product ‘outside’ or onto a surface
o True ‘ducts’ A. Holocrine glands
o Multicellular and unicellular (goblet cell) - High mitotic activity
o Situated in sweat (sudoriferous) and oil - Via apoptosis
(Sebaceous) glands - Actively dividing to replace the cells
 5 HISTOLOGY LAB EPIHELIUM TISSUE 02/15/2021

B. Merocrine glands
- Most common mechanism of excretion
of most glands
- Secretions will be contained in vesicles
- Excreted via exocytosis
C. Apocrine glands
- Excretes through accumulation f
secretions in the surface of the cell
particularly the apex
- Pinch off and going to be released

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