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Microscope Use, Tissue Classification,

and Nervous Tissue

BI 302L Week 1

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Microscope use Please read Exercise 3 in your Marieb lab manual Some common-sense rules

Be careful: microscopes and slides are fragileand expensive

Carry scope w/ 2 hands on arm/neck and base Do NOT drag the microscopes across the table Handle slides by edges only Start with 4x objective and coarsefocus knob When using higher-power objectives use only

finefocus knob

Never use 100x (oil-immersion) objective in thislab

Turn back to 4x objective and lower stagebefore removing slide

Make sure to return slides to proper box andslot Be sure you can see the pointer through the

eyepiece

coarse

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Body planes and sections

3D objects can look verydifferent when viewed in

different sections!

Tissues can be cut in

cross section,

longitudinal sectionor

somewhere in between.(a) cross section (x.s., c.s. on slides),

(b) longitudinal section (cut down the

bilaterally symmetrical midline, l.s. on

slides), and (c) longitudinal sections

in different planes.

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Some Common histological stains

Staining techniques preferentially color

components in cells.

H&E stains nucleiblue/purple and

cytoplasm pink

(make up the

majority of our slides)

Mason or Mallory-Azan are 3-colorstains that stain nuclei red, collagen

green or blue and cytoplasm red.

(we have several of these)

Silver stainingstains certain

proteins and DNAbrown

(reticular

connective tissue

slides)

Mason

Mallory-Azan

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Epithelial tissue

General characteristicsCovers and lines stuff

A lot of tightly packed cells; formscontinuous sheets

Avascular; relies on diffusionFree or Open/apical surfaceSupported by an

adhesive basement

membrane

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Epithelium

Named according to shape Squamous: thin and flat (scale-like) cells Cuboidal: cube-shaped cells Columnar: column-shaped cells

Named according to number of layers Simple: one layer Stratified: multiple layers

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Epithelium: Simple Squamous

Scale-like

Flat cells

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Epithelium

Nuclei are round and located in the centerof the cell

Simple cuboidal Simple columnar

The nuclei are usually oval (can beround) shaped and show polarity

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Epithelium

Stratified squamous Stratified cuboidal

Consists of two, sometimes three layers

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Epithelium

Nuclei line up in rows

Stratified columnar Pseudostratified columnarAll cells contact basement membrane,not all reach apical surface

TransitionalScalloped apicaledge, only in

urinary tract

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Connective tissue (CT)

Cells are widely spaced within an extensive, oftenfibrous extracellular (nonliving) matrix whichdetermines the characteristics of each specific CT.

4 categories of CT

CT proper (fibrous matrix): areolar, adipose,dense regular, dense irregular, reticular

Cartilage (gel matrix): hyaline, elastic,fibrocartilage Bone (solid mineral matrix) Blood and lymph (fluid matrix)

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Connective Tissue ProperAreolar CT

Elastic, collagen

and reticular fibers

(thick and thin)

crisscross haphazardly

Widely spaced

cells

Lots of

extracellular

matrix

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Connective Tissue Proper

Adipose

Few nuclei,visible at

periphery of cell

Dont confusewith simplesquamous, onlyone nucleus per

cell

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Connective Tissue Proper

Reticular CT

Silver staining:

Brownish or grayish

color

Dark stained reticular fibers Numerous nuclei Found in Lymphatic Organs and

surrounding small blood vessels

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Connective Tissue Proper

Dense Regular CT

Densely packed parallel collagenfibers

Nuclei of fibroblasts parallel andflattened

No lacunae distinguishes it fromcartilage

Fewer nuclei than smooth muscle

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Connective Tissue Proper

Dense Irregular CT

Irregularlyarranged

collagen fibers

Marbled or swirlyappearance

Major cell type isfibroblast

Fewer nucleithan smoothmuscle

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Connective Tissue

Hyaline Cartilage

Distinctivelacunae,

often paired

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Connective Tissue

Elastic Cartilage

Distinctive,large, often

paired

lacunae

Extensivedark elastic

fibers

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Connective Tissue

Fibrocartilage

Thick somewhatparallel collagen fibers

(red arrows)

distinct lacunae (blueand black arrows)

Intervertebral disc

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Connective Tissue

Bone

Concentric rings (like treerings) of Haversian

(dense) bone are

unmistakable

Spongy (cancellous ortrabecular) bone hasspicules.

Spongy Bone Haversian Bone

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Connective TissueBlood

Numerousround, red

blood cellsin

a featureless

matrix of

plasma

White bloodcells lessnumerous

and distinct

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Muscle tissue Functions to contract (shorten), causing

movement

Consists of long cells (fibers) arranged inparallel

3 subtypes you DO need to know Skeletal muscle Smooth muscle Cardiac muscle

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Skeletal muscle

Straight,parallel

fibers

Striations Peripheral

nuclei

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Cardiac muscle

Uninucleate cells Intercalated discs Branching fibers

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Smooth muscle

Spindleshaped cells

tightly packedtogether

Many morenuclei than

dense regular

or irregular

connective

tissue

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Nervous tissue

Neuron Cell Bodies

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Anatomical Structures of Neurons and

Neuroglia

AxonHillock

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Structural Types of Neurons

Bipolar Unipolar Multipolar

Multipolar:

One axon, several dendritesMost common

Unipolar:One short process that divides intoperipheral and central processes

Generally are sensory (conductimpulses to CNS)

Bipolar:2 processesRare; found in olfactory epithelium,retina, and cochlear/vestibular

ganglia

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Functional Types of Neurons

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Neuroglia

OligodendrocytesCNS-myelinates many axons

Schwann cells- PNS-myelinates one axon

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Nervous tissue:

longitudinal sections of nerves

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Nervous tissue:

cross sections of nerves