HUMAN HISTOLOGY (LABORATORY)

2ND SEMESTER- A.Y. 2023-2024

PRELIM
HISTOLOGY & ITS METHODS OF STUDY Darkfield Microscopy
● Field of view is dark and the
organisms are illuminated.
Histology ● A special condenser is used which
● Human body develops from single to multicellular causes light to reflect from the
specialized cells. specimen at an angle.
● The study of the tissues of the body and how these tissues ● Used for observing bacteria such as
are arranged to constitute organs. treponemes (which cause syphilis)
● Cells and Extracellular Matrix are two interacting and leptospira (which cause
components of a tissue. leptospirosis)
- ECM forms complex structure, supports the cells
and contains the fluid transporting in and out of the Phase-Contrast Microscopy
cell. ● Allows the examination of live
- Cells produces ECM locally unstained organisms.
- ECM and cells function together in a well ● Special condensers and objectives are
coordinated manner to give rise to fundamental used.
type of tissue. ● Alter the phase relationships of the
light passing through the object and
Preparation of Tissues for Study that passing around it.

Parts of the Microscope and Its Function

Important Properties of Microscope

1. Magnification
● The power of the microscope to enlarge the image of an
object

2. Resolution
● The power of the microscope to show detail clearly

Ocular Objective
10x red 4 = 40x (Scanner)
10x yellow 10 = 100x (LPO)
The Microscope 10x blue 40 = 400x (HPO)
10x black 100 = 1000x (OIO)
Microscope *only use lens paper to clean objectives
● Magnifies the image of such objects thus making them
visible to the human eye.
● Microscopes are used to observe the shape of bacteria,
fungi, parasites and host cells in various stained and
unstained preparations.
● A compound light microscope is the most common
microscope used in routine microscopic examination.
Binocular Monocular

Light Microscope
Parts of the Microscope
Brightfield Microscopy Eyepiece / Ocular
● Commonly used type of ● The specimen is viewed through the
microscope. eye-piece.
● The field of view is brightly lit so ● It has a lens which magnifies the image
that organisms and other formed by the objective. (10x)
structures are visible against it ● A pointer may be attached to the inside
because of their different of the eye-piece
densities.
 HUMAN HISTOLOGY (LAB)| 2ND SEMESTER | A.Y. 2023-2024

Diopter Adjustment Rules of Using a Microscope

● Change the focus on one eyepiece to ● Always carry with 2 hands
compensate for the difference in vision ● Only use lens paper for cleaning
between your two eyes. ● Do not force knobs
● Always store covered
Microscope Tube ● Be careful of the cords
● Attached on the top of the arm to support
the eye-piece on its upper end.

Nosepiece
● Attached under the arm of the
microscope tube.
● Houses the objective and rotates them.

Objectives
● Where the image of the specimen passes
first.
● 4x , 10x, 40x, 100x How to Use a Microscope
● Magnifying power is marked on the lens ● Place the slide on the stage
and usually color coded for easy ● Use stage clips to secure slide
identification. ● Adjust nosepiece to lowest setting
● OIO is used to provide best image at high - (Lowest = shortest objective)
magnification with the use of immersion oil. ● Look into eyepiece
● Has same refractive index as glass. ● Use coarse focus knob
● Focus your desired specimen.
Mechanical Stage
● Holds the slide and allows it to be moved to
the left, right, forward and backward using
the stage controllers
● Fitted with vernier graduations.

Condenser
● Illuminates the specimen and controls the
amount of light and contrast

Coarse Adjustment Knob

● Alters this distance rapidly and is used to
bring the specimen into the field of view
using an objective having low magnification
power.

Fine Adjustment Knob

● Changes the distance very slowly and
permits better viewing of the object.
● The movement should be smooth.

Rheostat
● A knob that is turned clockwise in order to
increase the light intensity, or
counter-clockwise to reduce the light.
 HUMAN HISTOLOGY (LAB)| 2ND SEMESTER | A.Y. 2023-2024

THE CELL Endoplasmic Reticulum

● Most extensive membranous structure in the cytoplasm.
● Visible with the use of fluorescent dye.
Cell ● Rough ER
● Basic functional unit of all living things ● Smooth ER
● Unicellular ● Serves as supporting structure of the cytoplasm
● Multicellular ● Production of numerous substances to be used within, or
exported by the cell.
Cell Membrane
● Protective covering of the cell.. Rough Endoplasmic Reticulum
● Determines which substance can move in and out of the ● Receives and processes proteins by the attached ribosomes
cell as well as the regulation of that substance. before handing to transfer vesicles.
● Attachment for the cytoskeleton. ● Occupies more of space in the Endoplasmic Reticulum.
● Provides binding sites and receptors.
● Cell-to-cell recognition. Smooth Endoplasmic Reticulum
● Made up of lipids. (Phospholipids)
● Site for synthesis of cholesterol and phospholipids
● Transports fatty acids and other lipids.

Golgi Complex / Golgi Apparatus / Golgi Body

● Intensely basophilic cytoplasm.
● Processes, sorts, packages the proteins from RER in the
form of secretory vesicles.

● Peripheral proteins (pp)

● Heads of the phospholipid molecules (h)
● Glycoproteins / glycolipids (gg)
● Tails of the phospholipid molecules (t)

Cytoplasm
● Refers to the cytoplasmic matrix that fills the cell and its Lysosomes
formed elements. ● Round or ovoid bodies
● Organelles —> permanent fixtures that support specific ● Diameter: 0.05 – 0.8 um
functions. ● Constitute in intracellular digestive system
● Inclusions —> temporary structures from pigments, lipids ● Principal components in heterophagy and autophagy.
and other substances. ● More on phagocytes.
● Fibrillar Elements —> maintain the shape and internal ● Intracellular use only
organization of the cell.
Peroxisomes
Cytoplasmic Matrix (Cytosol) ● 0.5 – 1.2 um
● >70% of volume is mainly made up with water. ● Spherical bodies that are present in most cells.
● Engaged in different biochemical processes ● Operate with enzymens outside the cell to catalyze
● Provides suitable milieu for the organelles in performing metabolic reactions.
their functions. ● Utilized by phagocytes in destroying the invading
microorganism.
Organelles
● Mitochondria Centrosome
● Ribosomes ● Consist of centrioles that are surrounded by granular
● Endoplasmic Reticulum structures, centriolar satellites.
● Golgi Complex ● Source of mitotic spindle during mitosis.
● Lysosomes ● Sources of cilia and flagellum of the sperm cell /
● Peroxisomes spermatozoon.
● Centrosome
Inclusions
Ribosomes ● Not present in all cells.
● 15 - 30 nm in size ● Generally temporary in the cell that may or may not be
● Seen via high magnification electron microscopy. membrane-bound.
● Clusters called polyribosomes / polysomes ● Fat Droplets, Glycogen (granules), crystals, lipochrome
● Free ribosomes pigments, lipocfuschin granules, etc.
o Sites for synthesis of protein that are for use
within the cell. Cytoskeleton
● Attached ribosomes ● Forms structural framework of the cell.
o Synthesis of proteins that will be exported as well ● Made up of microfilaments, intermediate filaments and
as usage within the cell. microtubules.
● Sites for protein synthesis where amino acids are
assembled into polypeptide chain.
 HUMAN HISTOLOGY (LAB)| 2ND SEMESTER | A.Y. 2023-2024

Nucleus Exocytosis
● Occupies the central region of the cell that makes the ● Transporting substance from the cell outside in the form of
largest structure inside the cell. secretory vesicles.
● Removal of nucleus leads to cell death.
● Date bank of the cell.
● Consist of nuclear matrix, chromatin, nucleoli.

Movement of Material Across Cell Membrane

Endocytosis
● Transport of substance from the extracellular space into the
cell.
● Phagocytosis —> Dust or particles
● Pinocytosis —> Liquid

Phagocytosis
● Phagocytes —> neutrophils and macrophage

Pinocytosis
● Alike phagocytosis but it does not need receptors to form
pseudopodia.
● Invaginates cell membrane to enclose a fluid that needs to
be ingested.
● Macropinocytosis / Micropinocytosis
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MIDTERM
Simple Squamous Epithelium
TISSUE INTRODUCTION & EPITHELIAL TISSUE Structure
● Single layer of flattened cells
Cells to Tissues Function
● Human body develops from single to multicellular
● Absorption, filtration
specialized cells.
● Not that effective for protection
● Body is an interdependent system, malfunction of one
group of cells is catastrophic.
Location
● Cells specialize into types of tissues, then organs.
● Walls of capillaries, lungs' air sacs
Tissues ● Form serous membranes in body cavity
● Groups of cells that are similar in structure and function.

Types
● Epithelium -coverings, linings of surfaces
● Muscle -movement
● Connective -support; bone, ligaments and fat
● Nervous -control; Brain, nerves, spinal cord

Function of Epithelial Tissue

● Protection - skin protects from sunlight, microorganism Simple Cuboidal Epithelium
and physical damage. Structure
● Absorption - lining of small intestine, absorbing nutrients ● Single layer of cube-shaped cells
into blood.
● Filtration - lining of kidney tubules filtering wastes from Function
blood plasma.
● Secretion and transportation in glands, filtration in kidneys
● Secretion - different glands produce perspiration, oil,
digestive enzymes and mucus.
Location
Characteristics of Epithelial Tissue ● Glands and ducts (pancreas & salivary), kidney tubules,
● Form continuous sheets (fit like tiles) covers ovaries
● Apical Surface - all epithelial cells have a top surface that
borders and open space (lumen)
● Basement Membrane - underside of all epithelial cells
which anchors them to connective tissue.
● Avascularity - lacks blood vessels; nourished by connective
tissue.
● Regenerate and repair quickly

Classification of Epithelial Tissue

Cell Shape
Simple Columnar Epithelium
● Squamous -flattened line fish scales Structure
● Cuboidal - cube-like
● Elongated layer of cells with nuclei at same level
● Columnar - column-like
Function
Cell Layer
● Absorption, protection and secretion
● Simple (one layer
● When open to body cavities (mucous membranes)
● Stratified (many layers)
- Named for the type of cell at the apical surface Location
● Linings of entire digestive tract

Special Features
● Microvilli, bumpy extension of apical surface, increase
surface area and absorption rate.
● Goblet Cells, single cell glands, produce protective mucus.
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Pseudostratified Epithelium Glands

Structure ● One or more cells that make and secrete a product.
● Irregularly shaped cells with nuclei at different (appear ● Secretion - protein in aqueous solution: hormones, acids
stratified but aren't) and oils.
● All cells reach basement membrane
Endocrine Glands
Function ● No duct, release secretion into blood vessels
● Absorption and secretion ● Often hormones
● Goblet cells produce mucus ● Thyroid, adrenal and pituitary gland
● Cilia (larger than microvilli) sweep mucus
Exocrine Glands
Location ● Contain ducts, empty onto epithelial surface
● Respiratory linings and reproductive tract ● Sweat, oil glands, salivary glands, mammary glands

Shapes of Exocrine Glands

Branching
● Simple - single, unbranched duct
● Compound - branched

Shape
● Tubular - shaped like a tube
● Alveolar - shape like flasks or sacs
Stratified Squamous Epithelium ● Tubualveolar - has both tubes and sacs in gland
Structure
● Many layers (usually cuboidal/columnar at bottom and Modes of Secretion
squamous at top) How the gland’s product is released

Function
● Protection
● Keratin (protein) is accumulated in older cells near the
surface

Location
● Skin (keratinized), mouth and throat)

Transitional Epithelium
Structure
● Many layers
● Very specialized (skin at base are cuboidal or columnar, at
surface will vary.
● Change between stratified and simple as tissue
stretched-out

Function
● Allows stretching (change size)

Location
● Urinary bladder, ureters and urethra

https://pressbooks-dev.oer.hawaii.edu/anatomyandphysiolog
y/chapter/epithelial-tissue/
 HUMAN HISTOLOGY (LAB)| 2ND SEMESTER | A.Y. 2023-2024

CONNECTIVE TISSUE Adipose Connective tissue

Location
● Present in subcutaneous layer deep in the skin, around the
Connective Tissue heart and kidneys
● The tissues connect and support other tissues of the body Function
● Prevents heat loose from body, act as reservoir of energy,
Function of Connective Tissue gives shape to the limbs and body, protects underlying
● Mechanical support organ from injury.
● Medium for exchange of nutrients and waste products
● Energy store and thermal insulation
● Defensive functions
- Barriers
- Engulf Bacteria
- Antibodies

Composition of Connective Tissue

Collagen Fibers Reticular Connective tissue

● Large fibers made of the protein collagen Location
● Typically the most abundant fibers.
● Present in the supporting framework of liver, spleen, lymph
● Promote tissue flexibility.
nodes, red bone marrow and around blood vessels and
muscles.
Elastic Fibers
Function
● Intermediate fibers made of the protein elastin.
● Branching fibers that allow for stretch and coil. ● Binds together smooth muscle tissue cells, filters and
removes microbes in the lymph node.
Reticular Fibers
● Small delicate, branched fibers that have same chemical
composition of collagen.
● Forms structural framework for organs such as spleen and
lymph nodes.

Classification of Connective Tissue

1) Loose Connective Tissue Dense Connective Tissue

1. Areolar connective tissue
2. Adipose connective tissue Dense Regular Connective tissue
3. Reticular connective tissue Location
● It forms tendon (attach muscle to bone) and ligaments
2) Dense Connective Tissue (attach bone to bone)
1. Dense Regular connective tissue Function
2. Dense irregular connective tissue ● It provides strong attachment to structure.
3. Elastic connective tissue

3) Cartilage
1. Hyaline cartilage
2. Fibro cartilage
3. Elastic cartilage

4) Bone Connective Tissue

1. Compact bone
2. Spongy bone Dense Irregular Connective tissue
Location
5) Liquid Connective Tissue ● Dermis layer of skin, membrane capsules around kidneys,
1. Blood Tissue liver, testes, heart valves and lymph nodes.
2. Lymph Function
● Provides strength to different organs.
Loose Connective Tissue

Areolar Connective tissue

Location
● Below the skin, fill space between muscles, supports blood
vessels and nerves in the alimentary canal.
Function
● Gives strength, elasticity and support to tissue.
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Elastic Connective tissue Spongy Bone

Location Location
● Present in tissues, walls of elastic arteries, trachea, ● Interior (epiphyses and metaphyses) of long bones
bronchial tubes, vocal cords Function
Function ● Structural support
● Provides stretching of various organs. ● Red Bone Marrow Production
● Mineral Exchange
● Flexibility

Cartilage

Hyaline Cartilage
Location Liquid Connective Tissue
● Present at the end of long bones,anterior ends of ribs,
nose and some parts of larynx, trachea, bronchi, bronchial Blood Tissue
tubes. Location
Function ● Heart and blood vessels
● Provides small surface for movement at joints, flexibility, Function
and support. ● Transportation
● Immune response
● Hemostasis
● Regulation

Elastic Cartilage
Location
● Present in pinna of ear and top of the larynx Lymphoid Tissue
Function Location
● Provides strength and elasticity and maintain the shape of ● Lymphatic system
certain organs such as the external ear. Function
● Immune responses
● Lymphocyte production and maturation
● Filtration and defense
● Fluid balance
● Antigen presentation

Bone Connective Tissue

Compact Bone
Location
● Diaphysis of long bones, outer layer of flat bones, surfaces
of short and irregular bones.
Function
● Structural support and rigidity to bones,protects bone
marrow and vital organs, reservoir for mineral storage,
facilitation of blood supply
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SEMI-FINAL
NERVOUS TISSUE The Peripheral Nervous System (PNS)
● Consists of ganglia, cranial nerves, spinal nerves and
peripheral receptors
Nervous System ● Ganglia = a collection of nerve cell bodies in the PNS
● The nervous system is the master controlling system of the ● Nerve = bundle of nerve fibers in the PNS
body. It is designed to constantly and rapidly adjust and ● Composed of cranial nerves and spinal nerves and their
respond to stimuli the body receives. It includes the brain, branches, ganglia and sensory receptors.
cranial nerves, spinal cord, and associated peripheral ● PNS is subdivided into sensory and motor divisions:
nerves. - somatic nervous system (SNS)
- autonomic nervous system (ANS) and the
Properties of Neurons - enteric nervous system (ENS)
1.Excitability (irritability): the ability to respond to
environmental changes or stimuli. Sensory or Afferent Division
2.Conductivity: respond to stimuli by initiating electrical ● Somatic sensory = senses touch, pressure, pain,
signals that travel quickly to other cells at distant locations. temperature, vibration and proprioception in skin, body
3.Secretion: Upon arrival of the impulse at a distant wall and limbs.
location the neuron usually secretes a chemical ● Visceral sensory = Autonomic sensory division -
neurotransmitter at a synapse that crosses the synaptic gap senses stretch, pain, temperature, chemical changes and
and stimulates the next cell. irritation in viscera; nausea and hunger.

Functional Classes of Neurons Motor or Efferent Division

● Sensory (afferent) neurons - afferent neurons are ● Somatic motor
specialized to detect stimuli and transmit the information to -Motor control to all skeletal muscles except
the CNS. They begin in any organ in the body but end in pharyngeal muscles.
the brain or spinal cord. ● Visceral Motor = Autonomic Nervous System - Four
● Interneurons (association neurons) - lie entirely in the -Sensory receptors convey information from visceral
CNS. They receive signals from many different neurons and organs (e.g. heart, lungs, intestines, etc.) to the
perform an integrative function "decision making" to CNS for integration and interpretation. A motor
respond to different stimuli. response is initiated that conducts impulses from
● Motor (efferent) neurons - efferent neurons transmit CNS to smooth muscle, cardiac muscle and/or
the appropriate response from the interneuron to an end glands for appropriate response
organ(muscle and gland cells) to carry out the body's
response to the stimuli. Autonomic Nervous System
● Two divisions of ANS
- Sympathetic division
- Parasympathetic division

CNS/PNS Summary

● Based on the direction of conduction

-Sensory or afferent conduct toward the CNS
-Motor or efferent conduct away from the CNS
-Interneuron interposed between sensory and
motor

Organization of the Nervous System Parts of a Neuron

● Two main divisions: ● Cell body-Trophic Unit
The Central Nervous System (CNS) ● Dendrites -Receptive Unit
● Consists of the brain and spinal cord with tracts and nuclei ● Axon -Conductive Unit
● Nucleus = a collection of nerve cell bodies in the CNS.
● Tract = bundle of nerve fibers within the CNS
● Brain + Spinal Cord
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Structural Classification of Neurons CNS: Microglia

● Neurons may be: Multipolar, Bipolar or Unipolar ● Thorny bushes in appearance and
● Determined by the number of processes attached to the the smallest glia
cell body ● Phagocytic function in CNS
● Originate from monocytes

PNS: Schwann Cells

● Form myelin sheath around peripheral axons
● Look like jelly roll with neurolemma cover
● Node of Ranvier separate each Schwann cell

Neurons
● Most (99%) neurons in the body are multipolar.
● Bipolar neurons are rare and occur in special sense organs
of the ear, nose and eye.
● Unipolar neurons begin as bipolar but processes fuse into
one. They are primarily sensory neurons.
PNS: Satellite Cells
Neuroglia Cells ● Surround neuron cell bodies within ganglia
● Found in CNS and PNS
● Perform a supporting function for neurons
● CNS
- Oligodendroglialcytes
- Astrocytes
- Ependymal cells
- Microglia Synaptic Ending
● PNS ● Synapse -site where two nerves communicate with each
- Schwann cells other.
- Satellite cells ● Presynaptic neuron - neuron that is conducting
Types of Glial Cells information toward the next neuron
● Postsynaptic neuron - transmits information away from
synapse
● Most synaptic communication is via chemical messengers
(e.g. acetylcholine, serotonin, norepinephrine, dopamine,
endorphins, GABA, glycine, glutamic acid, etc.)

Synaptic Terminals

Types of Synapses
CNS: Oligodendrocytes
● Axodendritic = axon to dendrite
● Form myelin sheath in CNS
● Axosomatic = axon to cell body
● Fewer branches than astrocytes
● Axoaxonic = axon to axon
Myelin
● Dendrodendritic = dendrite to dendrite
● Insulating layer around a nerve ● Dendrosomatic = dendrite to cell body
● Formed by oligodendrocytes in CNS
and Schwann cells in PNS
● Composed of a lipoprotein with
phospholipids, glycolipids and cholesterol.
● Myelination is process of myelin formation

CNS: Astrocytes
● Star shaped
● Blood brain barrier
● Most numerous
 HUMAN HISTOLOGY (LAB)| 2ND SEMESTER | A.Y. 2023-2024

BLOOD Colorized SEM Micrograph of Normal Erythrocyte

Blood
● Blood is a specialized connective tissue consisting of cells
and fluid extracellular material called plasma.
● Distributing vehicles transporting oxygen, carbon dioxide,
metabolites, hormones, and other substances.

Blood Preparation
● Collected blood in which the addition of anticoagulants
prevents clotting, can be separated to three layers by Buffy Coat
centrifugation according to heterogeneity. ● Leukocytes (WBCs)
● Blood cells histology can be studied in smears stained by - Granulocyte
Eosin (acidic) and Methylene Blue (Basic) •Neutrophil
•Eosinophil
•Basophils
- Agranulocyte
•Lymphocyte
•Monocyte
● Platelet (Thrombocytes)

Leukocyte

Composition of Blood

Plasma
● It is an aqueous solution, pH 7.4, containing substances of
low molecular weight that make up 7% of the volume and
the rest is water
Composition of Blood Plasma
● Water - 92%
● Proteins - 7%
● Others- 1%

Plasma VS Serum
Neutrophils
● Granulocytes with nuclei having 2-5 lobes linked thin
nuclear extensions
● Constitute 50- 70% of circulating leukocyte
● 1-4 days life span.
● First cell to arrive during the inflammatory process by
releasing of chemokines, cytokines and important lipid
mediators.
● PUS -Viscous, usually yellow collection of fluid formed
Red Blood Cells during the inflammatory process due to neutrophilic
● They are also called erythrocytes, are terminally secretions contains: apoptotic,neutrophils, bacteria,
differentiated cells, flexible biconcave in shape, lacking semi-digested material and tissue fluid.
nuclei and filled with oxygen-carrying protein called
hemoglobin
● Life span is about 120 days.
● Erythrocytosis (polycythemia) - increased
concentration of RBCs in the blood.
● Anemia - decreased or low concentration of RBCs in the
system.
 HUMAN HISTOLOGY (LAB)| 2ND SEMESTER | A.Y. 2023-2024
FINAL
Eosinophils HEMATOPOIESIS
● Far less numerous than neutrophils,constituting only 1-4%
of leukocytes.
● Bilobed nucleus Red Blood Cells
● Act to kill parasitic worms of helminths.
● Life span is about 1-2 weeks.
TERMINOLOGIES
● RBCs are formally called erythrocytes.
● Nucleated precursors in the bone marrow are called
erythroblasts
● Developing nucleated cells with normal appearance can be
called normoblasts
● Rubriblast terminology parallels the nomenclature used
Basophils for granulocyte development.
● Nuclei are always "baseball" round.
● Less than 1% of circulating leukocytes ● As hemoglobin develops, the cytoplasm becomes more
● The nucleus is divided into two irregular lobes.
magenta.
● Basophils and mast cells have surface receptors for IgE and
are responsible for hypersensitivity type 1. Three Erythroid Precursor Nomenclature Systems
● Life span is about several months.

Normoblastic Rubriblastic Erythroblastic

Pronormoblast Rubriblast Proerythroblast

Basophilic Prorubricyte Basophilic

normoblast erythroblast
Lymphocytes
● The most numerous type of agranulocyte and typically the Polychromatic Rubricyte Polychromatic
smallest leukocyte (polychromatophi (polychromatophi
● Spherical nuclei lic) normoblast lic) erythroblast
● Life span is about hours to many years.
Orthochromic Metarubricyte Orthochromic
normoblast erythroblast

Polychromatic (polychromatophilic) erythrocyte)*

Erythrocyte
*Polychromatic erythrocytes are called reticulocytes when
Monocyte
observed with vital stains.
● Monocytes are precursor cells of macrophages, osteoclasts, Pronormoblast/Rubriblast/Proerythroblast
microglia and other cells of the mononuclear phagocyte ● largest of the erythroid precursors
system. ● the "mother cell”
● The nucleus is large and usually c-shaped NUCLEUS:
● Monocytes' lifespan vary from hours to years.
● N:C ratio:4:1
● Chromatin : fine and dark
staining
● Nucleoli: 1-2

CYTOPLASM
● Heterogeneous
● Dark blue (distinctively
basophilic)
Platelets
● No granules
● Small, non-nucleated, membrane bound fragments.
● Originate by separation from the ends of cytoplasmic
Prorubricyte / Basophilic Normoblast (Erythroblast)
processes from giant bone marrow cells called
NUCLEUS
megakaryocytes.
● Controlling blood loss. ● N:C ratio:4:1
● Chromatin : partially clumped, ‘wheel w/ broad spokes’.
● Nucleoli: ABSENT

CYTOPLASM
● Deeply basophilic
● No granules
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Rubricyte / Polychromatic Normoblast (Erythroblast) LYMPHOID TISSUE

● "dawn of hemoglobinization"
● Last stage capable of mitosis
NUCLEUS:
● N:C ratio:1:1
● Chromatin : increasingly clumped
● Nucleoli: ABSENT

CYTOPLASM
● Mixtures of the red-staining of hemoglobin with the blue of
RNA in varying shades of gray
● Pink coloration mixed with basophilia → muddy, light gray
appearance

Lymphoid Tissue
● Specialized form of connective tissue
● Supporting framework: reticular cells & reticular fibres
● Large number of lymphocytes
● Other cells: Plasma cells & macrophages
Metarubricyte / Orthochromic Normoblast Consists of:
(Erythroblast) ● Lymphatic vessels
● Nucleated RBC ● Specific lymphoid organs
● Mitosis no longer possible - lymph node
NUCLEUS: - spleen
● N:C ratio:LOW - thymus
● Chromatin : Pyknotic (dense or compact) ● Lymphatic tissue found within the tissues of other
● Nucleoli: ABSENT organs
- Bone marrow
CYTOPLASM - GI tract
● Acidophilic (reddish pink) cytoplasm - Urinary tract
● Salmon-pink color - Respiratory tract

Functions:
● Defense of body
● Phagocytosis of foreign cells
● Involved in production of lymphocytes and plasma cells

Lymphatic Vessels
● Originate as lymph capillaries vessels
● Capillaries unite to form larger lymph
- Resemble veins in structure
Polychromatic Erythrocyte - Connect to lymph nodes at various intervals
● Called reticulocytes when stained with a vital stain Lymphatic Capillaries
● No nucleus
● Polychromatophilic as a result of the retention of RNA
● Synthesizing hemoglobin, for 2 to 3 days in the marrow
and for 1 day in the blood
● Seen in Wright's stain as large bluish-red cells,
polychromatophilic macrocytes

Erythrocyte (Mature)
● No nucleus
● Biconcave disc
● Salmon pink-staining cell with a central pale area
● Area of central pallor of 1 to 3 pm (1/3 of the cell) Lymphatic Vessels
● Circulate for about 120 days.

● PRONORMOBLAST
● BASOPHILIC NORMOBLAST
● POLYCHROMATIC NORMOBLAST
● ORTHOCHROMATIC NORMOBLAST
● POLYCHROMATIC ERYTHROCYTE
● ERYTHROCYTE
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Channels of Lymphatics LYMPHATIC NODULE

● Lymphatics ultimately deliver lymph into 2 main channels ● Circumscribed concentration of lymphatic tissue
(lymphocytes and related cells).
Right lymphatic duct ● Not surrounded by capsule.
● Drains right side of head & neck, right arm, right thorax
● Empties into the right subclavian vein LYMPHATIC ORGANS
● Circumscribed concentration of lymphatic tissue
Thoracic duct (lymphocytes and related cells)
● Drains the rest of the body
● Empties into the left subclavian vein Lymph Node
● Consists of connective tissue framework & numerous
lymphocytes.
● Bean shaped structures placed in pathways of lymphatic
vessels.
● Enclosed by a fibrous capsule
Cortex
● Outer portion
● Germinal centers produce lymphocytes

Medulla
● Inner portion
● Medullary cords

● Lymph enters nodes through afferent lymph vessels, flows

through sinuses, exits through efferent lymph vessel.

Major Lymphatic Vessel of the Trunk

Lymphatic Tissue
● 3 Types:
Diffuse lymphatic tissue
Medullary Sinus of a Lymph Node
● No capsule present
● Found in connective tissue of almost all organs ● Containing reticular cells with long processes and
elongated nuclei, macrophages, and many lymphocytes.
Lymphatic nodules (1) Macrophage;
(2) Reticular cell;
● No capsule present
(3) Trabecula.
● Oval-shaped masses
H&E stain. High magnification. (Courtesy of PA
● Found singly or in clusters
Abrahamsohn.)
Lymphatic organs
● Capsule present
● Lymph nodes, spleen, thymus

DIFFUSE LYMPHATIC TISSUE

● Called as mucosa associated lymphatic tissue (MALT).
● Accumulation of lymphatic tissue in the mucous membrane
of gastrointestinal, respiratory,urinary and reproductive
tracts.
● Located where they come in direct contact with antigens.
 HUMAN HISTOLOGY (LAB)| 2ND SEMESTER | A.Y. 2023-2024

Cells of Lymph Node ● Consists of 2 lobes (rt. & It.)covered by

● Lymphocytes connective tissue capsule.
● Plasma cells ● Septa passing inwards from the capsule
● Reticular cells subdivide the lobe into a large number
● Macrophages and other phagocytic antigen processing cells of lobules.
● Lymphatic and vascular endothelial cells ● Lobule: outer cortex, inner medulla
● Supporting stroma: epithelioreticular
Functions of Lymph Node cells
● Filtration of particles and microorganisms to keep them out
of general circulation. Thymic Lobule
● Interaction of circulating antigens in lymph with ● Cortex:
lymphocytes to initiate immune response. - Densely packed small
● Activation, proliferation of B lymphocytes and antibody lymphocytes.
production. ● Medulla:
● Activation, proliferation of T lymphocytes. - Lymphocytes are less densely
packed.
Spleen - Presence of Hassall's
● Largest lymphoid organ corpuscles
● Encapsulated
● Structure is similar to a node Functions of Thymus
- Capsule present ● Provides the environment for stem cells where they can
- But no afferent vessels or divide and mature into T lymphocytes.
sinuses ● Thymopoietin induces T cell production & maturation.
● Thymosin supports T cell activities.

Tonsils
● Multiple groups of large lymphatic nodules

Location
● Mucous membrane of the oral and pharyngeal cavities.
White pulp: Lymphoid Nodule (Malpighian corpuscle)
● 1.Germinal center Palatine Tonsil
● 2.Central artery ● Posterior-lateral wall of the oropharynx
● Aggregation of lymphatic nodules within diffuse lymphoid
tissue.
● Covered by stratified squamous epithelium.
● Tonsillar crypts (opening of numerous mucous glands)

Red Pulp of Spleen (Splenic cords: Cords of Billroth)

Functions of Spleen Pharyngeal Tonsil

● Filtration of blood. ● Posterior wall of nasopharynx
● Immune response against antigens circulating in blood.
● Site for production of B & T lymphocytes. Lingual Tonsil
● Formation of blood cells during fetal life. ● Base of tongue
● Storage of blood.
● Site of destruction of aged erythrocytes. Functions of Tonsil
● Production of lymphocytes.
Thymus ● Immunological response against antigens & organisms
Location coming in contact with epithelium.
● Behind the sternum in the mediastinum

Development
● Infant - conspicuous
● Puberty - maximum size
● Maturity - decreases in size

Function
● Differentiation and
maturation of T cells
 HUMAN HISTOLOGY (LAB)| 2ND SEMESTER | A.Y. 2023-2024
BLOOD SMEAR PREPARATION 8.) Label the slide with pencil on the frosted end (
Patient's name and date)
9.) Air dry then stain
Overview
● A peripheral Blood Smear enables the medical technologist
to view the cellular components of the blood. The
morphology of erythrocytes, leukocytes and platelets are
viewed to evaluate structure and maturity, size and
number.
● WBC Differential Count, RBC Morphology and PLT
Estimates are done using a well stained Blood Film

Specimen
● EDTA anticoagulated blood
● High quality smears can be obtained if they are done 2-3
hours of drawing blood
● If more than 5 hours, it will result to unacceptable blood
artifacts (echinocytic RBCs, spherocytes, vacuolated Features of a Well-made Wedge Peripheral Film
Neutrophils) ● The film is 2/3 to 3/4 the length of the slide.
● The film is finger shaped.
Methods ● The lateral edges of the film are visible
1.) Cover Glass Smear (Coverslip Technique) ● The film is smooth without irregularities, holes and streaks.
● Older technique ● If helds against the light, The feather Edge has a
● Inconvenient "Rainbow" appearance
● Only advantage is an excellent leukocyte distribution ● The whole drop of blood is piched up and spread
● Utilizes 2 cover slips (22 mm2)

2.) Wedge Smear (Manual Wedge Technique)

● The most convenient method and widely used.
● Requires 2 glass slides 3 inch by 1 inch (75mm X 25mm)

3.) Spun Smear

● Requires an automated slide making and staining system.
Drying
Coverslip Technique ● Slides are air dried
1.) Hold one coverslip by its 2 corners with the thumb ● Slides should be dried quickly as possible to avoid drying
and index finger. then place a small drop of blood. artifact
2.) Gently press the 2nd cover slip over the cover slip ● Blowing breath on a slide is not recommended because the
with blood moisture in breath can
3.) Separate the two cover glass by a rapid, even, ● Cause RBCs to become echinocytic or develop water/
horizontal, lateral pull. drying artifact.
4.) Allow smears to dry
5.) Stain Factors that will Affect Thickness of Smear

Factors Thin Thick

Angle Decrease Increase

Pressure/Speed Increase Decrease

Size of blood Decrease Increase

Wedge Smear Procedure

1.) Fill capillary tubes with blood (3/4 full)
2.) Place a small drop on one slide, about 2 mm in
diameter, half inch from the end of the slide.
3.) Hold the slide between your left thumb and
forefinger.
4.) Using the right hand, place the smooth clean slide
(Spreader) on the 1st slide just in front the drop of
blood
5.) Draw the spreader slide at 30 degrees angle
(30-45) and draw it back against the drop of blood.
6.) Allow blood to spread almost of the edges of the
slide
7.) Push the spreader forward with one light, smooth
fluid motion.