Basic Histology

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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


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.


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


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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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

Documents

Basic Histology