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Histology
What to look for
Histology review
Quiz = 40 pts
• Some slides set up
• Some pictures on the projector
Questions:
• What kind of tissue?
• General function? (e.g. absorption, protection)
• Cells, fibers, ground?
• An example of where would you find it?
Slides
• Epithelial tissues (7 types, could be ANY
of the examples provides)
• Connective tissues (11 types, ANY
example that we looked at)
• Integument and accessory structures
Epithelial tissue
Let’s review….
Simple cuboidal epithelium
• lining a tubule (longitudinal cut). Some of
the cell boundaries between "blocks" or
"cubes" here are quite distinct.
Simple Cuboidal
• Covers surface of ovary, lines kidney
tubules and small ducts of glands (thyroid
and pancreas)
Tubule - cross section
simple cuboidal
Another example - kidney
Type?
Simple squamous epithelium
• High power view of endothelial cells lining
a small blood vessel cut in cross-section.
(You see just the nuclei - the cytoplasm
between them is extremely flat.)
Endothelium = the simple squamous
epithelium lining blood vessels.
Simple squamous epithelium
Kidney
Superficial view
(squamous)
Type?
Simple columnar
• Another example – intestine, with goblet
Intestinal lining
Yet another
Type?
Pseudostratified ciliated columnar
epithelium
Trachea. Nuclei are at different levels. All
cells touch the basement membrane, but
only the taller cells reach the lumen. The
cilia are longer and less regular than the
microvilli of a striated border.
Pseudostratified
Columnar Epithelium
• Look like multiple layers
• Trachea
Figure 4–5b
Another example
Cilia – surface view
Type?
Bladder Low power
Transitional Epithelium
• Tolerates stretching
• Appearance changes (stratified to simple)
• Urinary bladder
Figure 4–4c
Type?
Stratified Squamous Epithelium
Figure 4–3b
Example
Example
Type?
Type?
Stratified Cuboidal Epithelium
• Sweat gland ducts
Figure 4–4b
Type?
Stratified Columnar Epithelium
• Rare
• Salivary gland duct
Figure 4–5c
Connective tissue
Connective tissues
Connective tissue proper
• Loose connective tissue
– Areolar
– Adipose
– Reticular
• Dense connective tissue
– Dense regular
– Dense irregular
– Elastic tissue
Fluid CT
–Blood
Supporting CTs
•Cartilage
–Hyaline cartilage
–Elastic cartilage
–Fibrocartilage
• Bone
Areolar tissue
• A loose CTP
Areolar
Areolar: what to look for
•
•
•
•
Fibroblasts
Collagen fibers
Elastic fibers
Mast cells and macrophages
• Found? Throughout body, under dermis,
divides skin from underlying tissues
Fibroblasts
• Resting fibroblasts typically have so little
cytoplasm that the cells appear, by light
microscopy, as "naked" nuclei
Fibroblast
Adipose tissue
• Another lose CTP (note nucleus)
Adipose: what to look for
• Lots of cytoplasm
• Slim nuclei pushed off the side
• Found? You know where
Reticular tissue
• The third type of loose CTP
Reticular tissue
Reticular: what to look for
• Reticular fibers (network)
• Found? Internal framework in many sort
organs (liver, spleen) supporting the
parenchyma
Dense CTP
• Dense regular – strength in one direction
• Dense irregular – strength in all directions
• Elastic tissue - pliable
Dense regular
Dense regular: what to look for
• Thick parallel bundles of collagen
• Small fibroblasts in between bundles
• Found? Tendons, ligaments, deep fascia.
Dense irregular
More dense irregular
Dense irregular: what to look for
• Mesh of collagen fibers (irregular looking)
• Interspersed fibroblasts
• Found? Dermis of skin, periosteum,
perichondrium
Elastic tissue
Elastic tissue: what to look for
• Elastic fibers (instead of collagen fibers) in
large bundles
• Fibroblasts
• Found? Between vertebrae, in blood
vessel walls (underneath endothelium)
Fluid CT
• Blood
Blood: what to look for
• RBCs
• White blood cells (darker): monocytes,
lymphocytes, granulocytes
• Platelets
Supportive CT
• Cartilage – gelatinous, padding
– Hyaline cartilage
– Elastic cartilage
– Fibrocartilage
Hyaline cartilage
• Glasslike because fibers not visible
More hyaline
• There are collagenous and elastic fibers
lying in the cartilage matrix but they are
invisible because their “refractive index” is
the same as that of the matrix (like cornea)
More hyaline
Hyaline cartilage
Hyaline
• Hyaline cartilage (lavender matrix), with
perichondrium (pink) outside it. The latter
is a dense regular collagenous CT.
Cartilage cells = chondrocytes, and they
are lying in the lacunae.
Hyaline cart.: what to look for
• Perichondrium
• Chondroblasts (make the matrix fibers and
ground)
• Chondrocytes and lacunae
• Where? Most joints, nasal septum
Elastic cartilage
Elastic cart: what to look for
•
•
•
•
Many elastic fibers in matrix
Perichondrium
Chondroblasts
Chondrocytes in lacunae
Fibrocartilage
Fibrocartilage: what to look for
• Irregular, wispy collagen fibers
• Chondrocytes, often stacked up
• Found? Intervertabral discs of spine, pads
in knee joint
Supportive CT: Bone
• Detail of lacuna, showing radiating canaliculi. Tissue fluid
from the capillaries and connective tissue of the
Haversian canal can seep through these spaces and
channels, bringing nutrients to the stellate osteocytes
residing there.
Bone: what to look for
•
•
•
•
•
•
Osteon (whole circular structure)
Concentric lamellae (of matrix)
Central canal (at center of lamellae)
Osteoblasts
Osteocytes in lacunae
Canaliculi
Found? Bones!
Integument
Epidermis and dermis
Epidermis
What to look for:
• Usually darkest between stratum
germinativum and stratum granulosm
(granulosm often a dark meandering line)
• Keratinized cells often lift off the section
• Melanocytes just below basal lamina
Dermis: Papillary vs. Reticular layer
What to look for:
• Papillary layer
– has ridges
– is areolar
– Just under basal lamina
• Reticular layer
– much thicker
– Dense irregular CT
Again
Merocrine sweat glands
Merocrine sweat gland
• What to look for:
– Found in most skin
– Coiled, tubular
– Small lumens in cross
section
– Have duct that goes all
the way to the
epidermal surface and
ends in sweat pore
– Smaller than apocrine,
don’t extend as deep
into dermis
Apocrine sweat gland
Apocrine sweat gland
What to look for:
• Associated with
hair follicle
• Only in nipples,
groin, armpit
• Large lumens
• Deeper in dermis
than merocrine
Hair with
sebaceous
glands and
arrector pilli
Hair
What to look for:
• Follicles are rarely complete
• Can often see root, papilla (at base, wher
hair grows)
• Arrector pilli muscle at an angle
• Associated glands (which are?)
Sebaceous
glands
Sebaceous glands
What to look for:
• Associated with hair follicle
• Found most everywhere hair follicles are
found in skin
• Look like cauliflower (maybe?)
Sebaceous follicle
Sebaceous follicle
What to look for:
• Also look like cauliflower
• Found on face and trunk only
• NOT associated with hair follicle
• Have duct that opens onto skin surface