Download Histology

Histology
Lindsey Bily
Anatomy & Physiology
Austin High School
HISTOLOGY
 The
study of tissues.
 There are four major types of
tissues in the human body:
Epithelial
Connective
Muscle
Nervous
Embryonic
Development of
Germ Layers

Zygote- a fertilized egg

Blastocyst- a hollow ball
of cells that forms after
the zygote undergoes
repeated mitosis. The
blastocyst is what
embeds into the uterus.

In the first two weeks of
conception, the primary
germ layers arise
Zygote to Blastocyst
Primary Germ Layers
Endoderm: innermost germ layer
a. digestive system
b. Linings of respiratory system
c. Some glands (thymus and thyroid)
Mesoderm: the middle layer
a. Muscles
b. skeleton
c. blood
d. Tissues that surround internal organs
Ectoderm: outer layer
a. Skin
b. Hair
c. nervous system
d. Outer glands
Primary Germ Layers
Epithelial Tissue
There are two types:
Membranous: covers the body
and organs or lines the body
cavities.
Glandular: form the secretory
units of glands.
Epithelial Tissue Functions
1.
2.
3.
4.
5.
Protection
Sensory- specialized structures in the skin,
nose, eye and ear
Secretion- glandular epithelium secretes
hormones, mucus, digestive juices and sweat
Absorption- absorb nutrients and exchange of
respiratory gases between the lungs and
blood.
Excretion- lining of kidney tubules excretes
urine.
Epithelial Tissue

The cells have very little intracellular
material.

packed tightly together.

Attach to a connective tissue basement
membrane.
Epithelial Tissue

Avascular (no blood vessels)

Cells connected together via
desmosomes and tight junctions.

Frequently under mitosis.
Basement Membrane

Made by epithelial cells and connective
tissue cells.
Epithelial cells secrete glycoprotein- basal
lamina
 Connective tissue produce a mesh of fibersreticular lamina
 Proteins called integrins bind the cell’s
cytoskeleton to the basal membrane

Simple Squamous
One layer of
flat cells.
Substances
can easily
diffuse or
filter through
them.
Simple Squamous

Linings of…

Blood vessels

Lymphatic vessels

Surfaces of pleura, pericardium, and
peritoneum.
Simple Cuboidal

One layer of cube
shaped cells . Seen
in many glands and
their ducts.

This is a cross
section of a kidney
tubule.
Simple Columnar

Single layer of long
cells. Usually are
modified (cilia,
microvilli, goblet
cells)

Line stomach,
intestines, uterus,
uterine tubules,
repiratory tract.
Simple Columnar

Goblet Cells: have large
vesicles to secrete
mucus
Mucus is made up of
water, glyco-proteins,
and electrolytes.
G in the picture are the
secretory vesicles
Pseudostratified Columnar
Found in the lining of air passages of the
respiratory system and in the male reproductive
system. Looks like it is more than one layer of
cells, but only a single layer touch the basement
membrane.
What type of Epithelium is this?
Pseudostratified columnar
What type of epithelium is this?
Simple Squamous
What type of epithelium is this?
Simple Cuboidal
What type of epithelium is this?
Simple Columnar
Stratified Epithelium
Different from simple epithelium in that is is
composed of multiple layers.
Stratified Squamous
Multiple layers of typical
flattened squamous
cells.
 Can be keratinized.
The keratin layer
provides the protective
characteristic of the
cells.
 Found in skin and hair

Stratified Squamous
Unkeratinized cells are found in the lining of
the vagina, mouth and esophagus. Its
surface is moist since there is no keratin.
Stratified Cuboidal
Protective function.
Found in sweat
gland ducts,
pharynx and part
of the epiglottis.
Stratified Columnar
Hard to see as
stratified as only the
most superficial layer
is obviously
columnar.
 Very rare, found in
the male urethra and
in the anus.

Stratified Transitional

Transitional epithelium is found in areas
that need to stretch

Almost only found in the urinary tract
Unstretched or relaxed
Stretched
Stratified Transitional
Unstretched
Stretched
Glandular Epithelium
Specialized epithelium that secretes
chemicals.
 May function as unicellular or multicellular.
 Glands

Exocrine: secreted products are discharged
into ducts.
 Endocrine (ductless): hormones are secreted
directly into the blood or interstitial fluid.

Glands

Exocrine Glands
salivary glands
sweat glands
oil glands

Endocrine Glands
pituitary gland
thyroid gland
adrenal glands
thymus glands
Structural Classification of
Exocrine Glands

Shape




Tubular
Alveolar (saclike)
also called “acinar”
Simple- one duct to
surface
Compound-more than
one duct to surface
Functional Classification of
Exocrine Glands

Classified by the method in which they
discharge their secretions.
Apocrine

Holocrine

Merocrine

Apocrine Glands



Part of the cell
pinches off with the
secretory product.
Loss of cytoplasm
and damage to the
cell, but it is repaired
quickly.
Ex. Mammary Glands
Apocrine Glands
Notice how each cell is a little
pointed at the tip. That is called
its apical end or apex.
Holocrine Glands



The literally erupts as
their secretory
product is released.
This completely kills
the cell. They self
destruct.
Ex. Sebaceous
glands produce oil in
the skin
Holocrine Glands

Cross section of skin.
The sebaceous
glands are holocrine
glands.
Merocrine Glands




Most common type of
gland.
The cell releases its
product by
exocytosis.
No damage to the cell
or loss of cytoplasm.
Ex. Salivary glands
Merocrine Glands
Cross section of a
salivary gland.
See where the
duct is labeled.
 What kind of
epithelial tissue is
this gland made
of?
Stratified Cuboidal

Duct
Connective Tissue






Most widespread tissue in the body.
Found in or around every organ in the body
Connects (muscles to muscles; bones to bones
muscles to bones)
Supports (skeleton)
Transports (blood)
Defends (white blood cells)
Connective Tissue
•
•
•
Mostly intercellular matrix that is composed of…
Ground substance: composed of fibers, fluid and
few cells
Fibers can be collagenous (white), reticular or
elastic.
•
•
•
Collagenous made of collagen bundles
Reticular occur in networks and are delicate
Elastic contain elastin and can return to its original
length after being stretched.
Fibrous Connective Tissue
Loose Connecive Tissue
Stretchable
 Found almost everywhere between other tissues and
organs
The matrix consists of:
elastic and collagenous fibers
fibroblasts-cells synthesize ground substance
macrophages-derived from white blood cells.
(phagocytosis)

Loose CT
In the watery matrix (ground substance) observe the nuclei of
fibroblasts , collagen fibers and elastic fibers.
Locations: beneath the skin and around blood vessels,
muscles and nerves
Functions: binds one tissue to another (as skin connects to
muscle), protection and nourishment to the organs and
structures it binds, and stores "body fluid"
Adipose Tissue




Mostly fat cells.
Few fibroblasts and
macrophages and
mast cells
“A” is the lipid in
surrounded by a
cell membrane.
“N” is the nucleus
along with the
cytoplasm.
Reticular Connective Tissue
Observe that the reticular fibers (A) form a network or lattice
in this spleen tissue.
Locations: spleen, lymph nodes, liver, bone marrow
Function: gives support to soft organs and filters the blood
and lymph. Reticular cells phagocytize bad substances.
Dense Fibrous Tissue (Regular)
The fibroblasts (A) are more clearly observed
between the parallel collagenous fibers (B).
Locations: tendons and ligaments
Functions: strong flexible support
Dense Fibrous Tissue (Irregular)
Skin
Bone Tissue
In the compact bone micrograph at the left, several complete
osteons are visible. In the center of the osteon is the central
canal (A) which hold the blood vessels and a nerve. These
canals are surrounded by concentric rings of inorganic matrix,
the lamellae (B). Between the lamellae are bone cells, the
osteocytes (C) located in lacunae. Nutrients diffuse from cell
to cell through the canaliculi (D).
Location: skeleton
Function: framework, protection
Cartilage





Made up of chondrocytes
Avascular and so nutrients have to diffuse
from the blood vessels through the
perichondrium to the cells.
Chondrocytes do not replicate quickly.
Cartilage injuries heal slowly.
Ex. Torn cartilage, rheumatoid arthritis,
infection, joint dislocation, torn meniscus, torn
ligament.
Hyaline Cartilage



Hyaline comes from the Greek word “hyalos” or
glass.
Low amount of collagen so it is shiny and
translucent.
Found in the support rings of the respiratory
tubes and the ends of bones that articulate at
joints.
Hyaline Cartilage
The chondrocytes (A) are located in lacunae (C). The
matrix (B) contain collagen fibers that are so fine they
are not visible in tissue preparations.
Locations: "C" rings in the trachea, nose, articular ends
of bones, fetal skeleton
Function: precursor to bone, support
Fibrocartilage
Strongest and most durable type of cartilage.
Serve as shock absorbers between
intervertebral disks and in the knee joint.
Damage to the menisci are common in
athletes.
Elastic Cartilage
The chondrocytes (A) are contained in lacunae (C). The
matrix (B) contains abundant elastic fibers and hardly
any cartilage. These fibers give great flexibility to this
tissue.
Locations: ear, auditory canal, epiglottis
Functions: flexible support
Blood


Very unusual for connective tissue. It is a liquid,
no fibers, or ground substance.
Divided into plasma and blood cells.



erythrocytes-red blood cells
Luekocytes-white blood cells
Thrombocytes- platelets
Blood
Note the red blood cells, platelets, and leukocytes located
within this slide. Note the variety in the nuclear morphology
and granule characteristics (size and color) seen within the
leukocytes.
Muscle Tissue

Three types named after their location
 Skeletal
 Muscles attached to bones
 Smooth
 Muscles found in the wall of the viscera
(hollow internal organs)
 Cardiac
 Muscles that make up the wall of the heart
Skeletal Muscle

Voluntary- we can control the muscle movement
or will it to happen.

Striated- stripes that can be seen under the
microscope

Cells have many nuclei and are long and
threadlike.

The cells are often called muscle fibers.
Skeletal Muscle
Notice the striations, multiple nuclei, and
shape of the cells (fibers). The sarcomere
is the contractile unit of the cell, but we will
focus on the sarcomere during the
Muscular System unit.
Smooth Muscle

Found in walls of hollow internal organs.
stomach, intestines, blood vessels
•
Involuntary- we cannot control the movement.
Nonstriated (hence the name smooth)
Long narrow fibers, but not as long as skeletal
muscle fibers.
One nucleus per cell.
•
•
•
Smooth Muscle
Notice the long narrow shape.
One nucleus per cell (fiber)
Locations: walls of hollow organs, i.e. stomach,
intestine, uterus, ureter
Functions: involuntary movement - i.e. churning of food,
movement of urine from the kidney to the bladder,
partuition
Cardiac Muscle

Striated

Involuntary

Intercalated Disks (dark bands)- this is where
the plasma membranes of two cells join
Cardiac Muscle
Notice the fibers, intercalated
disks, and one nucleus per cell.
Muscle Tissue
Nervous Tissue

Tells all parts of the body what to do.

The Nervous System is composed of the brain,
spinal cord, and nerves.

Arises from the ectoderm.

Neurons (nerve cells) and neuroglia (supporting
cells)
Neuron
Nervous Tissue
Tissue Repair

Regeneration: Phagocytic cells remove the
injured or dead cells and then new cells fill in
the gaps.

Epithelial cells and connective tissue cells have the
greatest capacity to regenerate

When a break occurs in the epithelium, the cells will
rapidly undergo mitosis to produce daughter cells to
fill in the wound.
Tissue Repair



When the connective tissue is damaged,
fibroblasts fill in the gap with a dense mass of
fibrous connective tissue.
If the mass is small, it usually is replaced by
normal tissue later.
If it is deep or very large, it may remain as a
fibrous mass. This is a SCAR.
Tissue Repair
Scars

Regular scars

Keloid: the collagen
keeps growing and
becomes larger than
the actual wound.
Tissue Repair/Muscle Tissue

Muscle tissue doesn’t repair itself very well.

Damaged muscle tissue is usually replaced
with fibrous connective tissue.

If a muscle is damaged, it generally never
heals well and loses some or all of its function.
Tissue Repair/Nervous Tissue



Nervous tissue is similar to muscle tissue in
that it doesn’t repair itself well.
Neurons outside the brain and spinal cord can
sometimes regenerate but it’s very slow and
must have supporting neuroglia there to help
them.
In adults, cells in the brain and spinal cord do
not regenerate, so the damage is usually
permanent.
Inflammation


The way in which cells and tissues react to
injury.
Also called the inflammatory response.
4 signs:
rubor (redness)
calor (heat)
tumor (swelling)
dolor (pain)
Inflammation


1. Immediately after injury the blood vessels
dilate (open) and blood flow increases.
2. The injured tissues release chemicals that
affect the blood vessels.

Histamine, seratonin, and kinins tell the blood vessels
to dilate and allow the components that normally stay
in the blood to be allowed to “leak” into the tissue
spaces.
3. White blood cells leave the blood vessels and
migrate into the interstitial space at the site of the
injury.
Inflammation
4. Leukocytosis-promoting factor (LP) is also
released by injured tissue.
-Stimulates the release of white blood cells
from their storage areas and increases the number
of circulating white blood cells.
5. The accumulation of dead leukocytes and tissue
debris can cause pus at the focal point of the
infection.
Inflammation

6. Edema: The tissues can start to swell
because of the accumulation of blood, white
blood cells, tissue debris and leaked
substances.
Inflammation

Rubor (redness): increased blood flow and
pooling of blood following injury.

Calor (heat): increased blood flow to the injury.

Tumor (swelling): edema and accumulation of
the fluids, tissues, and clot in the tissue spaces.

Dolor (pain): kinins and other chemicals activate
pain receptors near the injury site.
Membranes
Thin, sheetlike structure that…
*cover and protect the body surface
* line body cavities
*cover the inner surface of hollow organs
*anchor organs to each other or to bones
*cover internal organs
Some membranes secrete lubricating fluids that
reduce friction during beating of the heart, lung
expansion, bones and joints.
Epithelial Membranes

Epithelial membranes are made of epithelial
tissue and specialized connective tissue.
Cutaneous membrane: skin
 Serous membrane: lines body cavities and covers the
surfaces of organs in the cavities.
-Parietal membrane: lines the walls of the cavity like
wallpaper
-Visceral membrane: covers the surface of the
organs.
Ex: pleura (thoracic and lungs)
pericardium (heart)
peritoneum (abdominal cavity and abdominal
organs)

Epithelial Membranes

Mucous Membranes
Line surfaces opening directly to the exterior
Ex. Respiratory tract, digestive tract, reproductive
tract

Mucus acts as a lubricant for food as it moves along
the digestive tract.
It also is a sticky trap for contaminants in the
respiratory tract.
Connective Tissue Membrane
Do not contain epithelial tissue.
 Synovial membranes line the spaces
between bones and joints.
 The lubricating fluid they secrete is called
synovial fluid.

Cancer
Neoplasms: “New matter” also called
tumors.
 Benign: do not spread to other tissues
 Malignant: spread to other regions of the
body. (metastasis)

Cancer

Benign tumors
Papilloma
 Adenoma (glandular tumor)
 Nevus (small, pigmented skin tumor)
 Lipoma( adipose tumor)
 Osteoma (bone tumor)
 Chondroma (cartilage tumor)

Cancer

Malignant Tumors- Epithelial (carcinomas)
Melanoma (skin pigment cell cancer)
 Adenocarcinoma (glandular cancer)

Cancer

Malignant Tumor Connective Tissue
(sarcoma)
Lymphoma (lymphatic cancer)
 Osteosarcoma (bone cancer)
 Fibrosarcoma (cancer of fibrous connective
tissue)

Cancer
Hyperplasia: too many cells
Anaplasia: abnormal, undifferentiated cells
Genetic factors and carcinogens