1. Biology 101 Laboratory September 2009
EXERCISE VI
HISTOLOGY
Tissue 4 Major Types of Tissues
• group or aggregation of cells 1. Epithelial Tissues
• display common functional or morphological 2. Connective Tissues
properties or both 3. Muscular Tissues
4. Nervous Tissues
Histology
• study of microstructure of tissues
I. EPITHELIAL TISSUES
Covers external surfaces of the body or lines cavities
Lacks vascular supply but are nourished by diffusion from capillary beds in the underlying CT
Derived from the three embryonic layers
For protection; secretion, absorption, lubrication & sensory perception
Basal membrane/Basal lamina – thin membrane that bounds the epithelial tissues to the underlying
connective tissues
According to Shape: According to Number of Cell Layers:
1. Squamous 1. Simple
2. Cuboidal 2. Stratified
3. Columnar 3. Pseudostratified
4. Transitional
Epithelium
Simple Squamous Epithelium
Source: inner lining of cheek
Epithelium
Simple Cuboidal Epithelium
Source: kidney tubules
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2. Biology 101 Laboratory September 2009
Simple Columnar Epithelium
Source: stomach or small intestine
• highly absorptive surfaces → small intestine
• secretory surfaces → stomach
• may be specialized for secretion → goblet cells in the small intestine
Stratified Squamous Epithelium
Source: skin
• Composed of epithelial tissues with more cell layers
• Only cells of the lowest layer touch the basement membrane
• Basal layer consists of columnar or cuboidal cells → undergoes continuous mitotic division
• Cells near the surface are flattened, consists of squamous cells
Pseudostratified Ciliated Columnar Epithelium
Source: trachea
• ‘pseudo’ → false
• Cells appear to be arranged in more than one
layer but all of them are attached to the basal
membrane, thus are actually single layer of cells
• Pointed structure: microvilli (hair-like
structures)
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Transitional Epithelium
Source: urinary bladder
• Transition between stratified squamous & columnar epithelium
• Cells change their form
• Found in hollow organs subject to contraction & stretching
II. CONNECTIVE TISSUES
Bind, anchor, and support body parts
Abundant cellular matrix
Originate from the mesenchyme, the embryonic connective tissue that develops from the mesoderm
2 Types:
1. Connective Tissue Proper – for binding organs
2. Specialized Connective Tissues – binding & other specific functions
Connective tissue fibers:
1. Collagen fibers – thick, un-branched, appear wavy; show resistance to stretching
2. Elastic Fibers – thin & less wavy than collagen fibers, branched; easily stretched but return to
normal length when tension is released
3. Reticular Fibers – extremely fine & highly branched forming network
Connective Tissue Proper
Loose or Areolar Connective Tissue Dense Connective Tissue (Tendon)
• Large amount of tissue fluid, many cells, few • More fibers, less ground substance & cells
fibers
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4. Biology 101 Laboratory September 2009
Connective Tissue:
Specialized Connective Tissue:
Adipose Tissue
• Store fats in the form of triglycerides
• Stores nutrients, provides insulation, & acts as cushion; fills
crevices in organs
• Adipocytes → fat cells
Cartilage
• Soft & pliable 3 Types of Cartilage based on Matrices:
• Chondrocytes → cartilage cells 1. Hyaline Cartilage
2. Elastic Cartilage
• Lacuna → cartilage matrix
3. Fibrocartilage
• The lacuna houses the chondrocytes
Hyaline Cartilage:
Source: trachea • Clear homogenous matrix
• Perichondrium → dense connective tissue at the periphery
of the cartilage
• Spindle-shaped lacunae
Elastic Cartilage Fibrocartilage
Source: epiglottis & external ear • Resembles connective tissue proper
• Contains collagen fibers, & a network of elastic • Consists of a network of collagen fibers
fibers • Lacunae → round or oval
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5. Biology 101 Laboratory September 2009
Specialized Connective Tissue (continuation)
Bone
For support, protection, movement, forming blood cells;
reservoir of calcium
Lamellae → matrix
Haversian canal
Osteocytes → bone cells
Lacunae
Canaliculi → minute canals radiating from the lacunae
Haversian System or Osteone – composed of haversian canal,
lamellae, osteocytes, lacunae, & canaliculi
Volkman’s canal – canals that runs diagonally/right angles to
the Haversian canal
Blood
Transport medium
Consists of cells, matrix, & intercellular fibers
Cellular elements: erythrocytes, leucocytes, & thrombocytes
Matrix: liquid called plasma
Function: transporting gases & substances to and from the different parts of the body
1. Erythrocytes or Red Blood Cells
Oxygen carrier
carries hemoglobin
2. Leucocytes or White Blood Cells
For body defense against microorganisms by their phagocytic action & antibody production
a. Granular WBC
♦ have a granulated cytoplasm & multi-lobulated nucleus connected by chromatin strands
♦ function as phagocytes
b. Agranular WBC
♦ cells without granules in the cytoplasm
♦ are transformed into large phagocytic cells called macrophages
3. Platelets
also, thrombocytes
small, non-nucleated, colorless, round or oval, non-motile corpuscles
functionally related to blood clotting
Human RBC Frog’s RBC
Granulated WBC Agranulated WBC
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III. MUSCLE TISSUES
• specialized for contraction
• contains contractile proteins – allows them to shorten their lengths
• muscle cells → muscle fibers
• 3 Types of Muscle Tissues:
1. Skeletal muscle
2. Smooth muscle
3. Cardiac muscle
Skeletal Muscle
• connected to the skeleton
• concerned with body movement
• striated; voluntary in action
• skeletal muscle cells: cylindrical, striated & multinucleated; oval nuclei are at the periphery of the cell
• Fasciculi – muscle fibers grouped into bundles
• Endomysium – connective tissue meshwork enveloping the muscle fiber
• Perimysium – connective tissue sheath joining the fasciculi
• Epimysium – holds together the whole muscle mass
Smooth Muscle
• found as part of the walls of the viscera (internal organs)
• non-striated; involuntary in action
• smooth muscle cell: spindle-shaped cells in side view with
a single centrally located nucleus at the widest part of the
cell
• cytoplasm is homogenous
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Cardiac Muscle
• comprises the contractile wall of the heart; also found in the roots of large blood vessels arising from the
heart
• specialized to contract automatically & rhythmically
• striated, branched; involuntary in action
• presence of intercalated discs → dark bands
IV. NERVOUS TISSUES
• specialized to receive stimuli from the environment or from the various organs of the body
• transmit impulses to the nerve centers in the brain & spinal cord
• composed of 2 Types of Cells: Neurons & Neurologia
Neuron
• consist of nerve cell body → soma or perikaryon 2 processes (nerve fibers): 1 axon & 1 dendrite
perikaryon
aryon;
1. axon
thinner & longer compared to the dendrite, branches extensively
gradually decreases in diameter as it furthers the cell body
conveys impulses away from the cell body
2. dendrite
short & confined near the cell body
may be more than one process in a neuron
have thorny appearance
conveys impulses towards the cell body
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8. Biology 101 Laboratory September 2009
• Types of Neurons (based on Processes)
a. Multipolar Neuron – 1 axon & several dendrites
b. Bipolar Neuron – 1 axon & 1 dendrite; least numerous
c. Unipolar Neuron – 1 process that separate into an axon & a dendrite
Teased Nerve:
Myelin Sheath – appears as a tube surrounding the axis cylinder
(cytoplasm of the axon); produced by Schwann cells
Nodes of Ranvier – regions in the myelin sheath that appears
interrupted
Neurologia
• supporting cells of the neurons
• possess several branching processes
Cross Section of Nerve:
Fascicle → single discrete bundle of nerve fibers & connective tissue
Epineurium → connective tissue that binds several fascicles in nerve trunks
Perineurium → dense connective tissue covering each fascicle
Endoneurium → covers individual nerve fibers
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