Basic Histology
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Transcript of Basic Histology
9/29/2010
1
Zoology 100 Lab
HISTOLOGY:
Key facts and
Images
Ma. Victoria B. PangilinanUST - College of Science
Department of Biological Sciences
Metazoan HistologyHistology - study of tissues and its microstructure
Tissues - group of cells specialized for a common
function
4 kinds of tissues:
1. Epithelial
2. Connective
3. Muscular
4. Nervous
Epithelial Tissues
• sheet of cells that covers
external surfaces of the body
or lines cavities.
• also forms glands of the
body.
• tightly packed due to
junctional complexes on cell
surfaces (little extracellular
spaces in between).
Epithelial Tissues• firmly bound to underlying connective tissue by a thin membrane called basal lamina or basement membrane.
• Lacks vascular supply, but nourished by diffusion from capillary bed in underlying connective tissues
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Epithelial TissuesAccording to shape:
1. Squamous – flat2. Cuboidal - box3. Columnar - tall
According to number of cell layers:
1. Simple – 1 layer2. Stratified – several layers3. Pseudostratified – one
layer, “appearing several layers”
4. Transitional – relative
Simple Squamous
Lung alveolusScraped
Cheek Cells
• single layer
• flat
• clear cytoplasm
• oval nucleus
• cell outlines range from wavy,
serrated to smooth.
• lines blood capillaries, lungs.
• permits passive diffusion of
gases and nutrients into and out
of cavities .
Simple Cuboidal
Kidney Tubules
• single layer
• short, box-like
• rounded nucleus
• lines small ducts and tubules
(salivary glands and kidneys)
• have secretory and absorptive
functions
Simple Columnar
Stomach lining Small intestine lining
• single layer
• tall version of cuboidals
• rectangular
• elongated nucleus located near
base
• found in highly absorptive
surfaces (intestinal tract)
• cells bear microvilli
• in female reproductive tract—
ciliated.
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Stratified Squamous
Tongue Skin
• two to many layers of squamous
cells
• withstand mild mechanical
distortion
• lines the esophagus, anal canal,
vagina.
• basal cells undergo continous
mitosis
Pseudostratified Ciliated Columnar
Trachea
• tall rectangular cells in a single
layer, appearing two.
• elongated nucleus
• with microvilli or cilia
• with goblet cells in some
• basal cells render the “double”
layer.
Transitional Epithelium
Urinary bladder
• number of cells vary depending
on whether the organ in
contracted or not
• cells shapes are not strictly
squamous, cuboidal or columnar.
• specialized to accommodate great
stretching
• found in urinary tract and bladder
• relaxed – 4 - 5 layers :
stretched – 2 - 3 layers
Connective Tissues
• bind, anchor, and support tissues
• composed of relatively few cells, many extracellular fibers, fluid and a
ground substance or matrix
• Ground substance or matrix –
amorphous, transparent, colorless
surrounding the fibers and cells
Three major types:
1. Loose connective tissues2. Dense connective Tissues
3. Specialized Connected tissues
First two types are classified under
connective tissue proper
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Fibroblasts
• have large, ovoid, nuclei.
• have dispersed
cytoplasmic processes.
• synthesize fibers, the
ground substance, as well as
macrophages.
Types of Fibers
Collagen fibers – thick, unbranched, and in spreads (B)
Elastic fibers – thinner than collagen fibers, less wavy and
branched (C).
Reticular fibers – thinnest among the three, fine, delicate,
branch extensively to form a network (D)
Connective Tissue Proper:
Loose Connective Tissue• also called areolar connective tissue.
• “packing material” of the body, anchoring blood vessels,
nerves and body organs.
• contains fibroblasts, fibers, matrix, and macrophages
Connective Tissue Proper:
Dense Connective Tissue
Tendon
• forms tendons, ligaments and fasciae (bands of tissue
surrounding the skeletal muscle.
• collagenous fibers are long and tightly packed together.
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Specialized Connective Tissues:
Adipose Tissue
• have abundant adipocytes—store fats as large droplets of
triglycerides
• nucleus at the periphery (signet ring configuration)
• provides insulation, act as cushions, fill in crevices in
organs
Specialized Connective Tissues:
Cartilage
FibrocartilageHyaline Elastic
• soft and pliable.
• chondrocytes – cartilage cells.
• lacunae – spindle shaped cavities where chondrocytes are located.
3 types of cartilage:
1. Hyaline – possess clear, homogenous matrix. (trachea)
2. Elastic – possess elastic fibers (epiglottis, external ear)
3. Fibrocartilage – with network of collagen fibers, and chondrocytes.
Specialized Connective Tissues:
Bone Tissue• for support, protection, movement,
forming blood cells.
Parts of a compact bone:
1. lamellae – matrix
2. Haversian canal – longitudinal
3. Osteocytes – bone cells
4. Lacunae – cavities housing
osteocytes
5. Volkmann’s canals – at right angles
#’s 1 – 4 are collectively the
Haversian system or osteon
Specialized Connective Tissues:
BloodRBC – circular cells without nucleus in humans, nucleated in frogs.
Granulated WBC’s
1. Eosinophil – two-lobed nuclei, reddish color in stain.
2. Basophil - S-shaped nucleus, blue cytoplasm.
3. Neutrophil – 3-5 lobed nuclei, lavender cytolasm
AgranulatedWBC’s
1. Lymphocytes – large nucleus indented on one side, thin cytoplasm
2. Monocytes – oval or kindney-shaped nuclei, irregular cytoplasm
Platelets – minute cytoplasmic fragments, stain blue
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Specialized Connective Tissues:
Blood
Red Blood Cells
Muscle Tissues
Skeletal Cross section
muscle bundle
Teased skeletal
muscle
• connected to the skeleton, VOLUNTARY, striated.
• concerned with body movement
• skeletal muscles are cylindrical, striated, multinucleated, the nucleus being oval
and located at the periphery of the cell.
• fasciculi – muscle bundles
• endomysium – tissue covering single fiber
perimysium – tissue covering fasciculi
epimysium – tissue covering entire muscle mass
Muscle Tissues
Smooth Muscle
• found as part of walls of viscera / visceral organs, INVOLUNTARY.
• individual muscle cell appear as spindle-shaped cells, with single
centrally located nucleus at the widest part of the cell.
• cytoplasm is fairly homogenous, unstriated.
Muscle Tissues
Cardiac Muscle
• composes the contractile wall of the heart, INVOLUNTARY.
• arranged as branching networks interspersed with capillaries.
• nucleus centrally located, one per cell, cells striated.
•With interacalated discs – boundaries between neighboring cells.
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Nervous Tissues
Nervous system is divided into:1. Central nervous system (CNS) which includes the
brain and spinal cord, and the
2. Peripheral nervous system (PNS) which includes nerves and ganglia.*Nerves consist of axons in the PNS bundled together.*Ganglia are collections of neuron cell bodies.
Nervous Tissues
Nerve cells include neurons and neuroglia(supporting cells).
Neurons (cells) are specialized to produce and conduct
electrochemical impulses.
Neuroglia=do not conduct electrical impulses but instead
support and insulate neurons and eliminate foreign materials in and around neurons.
Myelin sheath - insulating covering of neuroglia cells
wrapped around axons
Nodes of Ranvier - separate adjacent neuroglia cells
Nervous Tissues
Neurons X-S of Nerve Trunk Teased Nerve
Nervous Tissues
Multipolar and
Bipolar NeuronsUnipolar Neurons
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Nervous Tissues
X-S of Nerve Trunk