HISTOLOGY
Topic 1 | 1st Shifting
Dr. Jacqueline Mupas-Uy
LEGENDS
August 12, 2022
PPT, Lecture
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TOC
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I. THE CELL
A. 2 Types of the Cell
B. Parts of the Cell
C. Other Unique Structures of the Cell
II. ULTRASTRUCTURE OF THE CELL
A. Cell Membrane
1. 2 Models
2. Phospholipid Bilayer
3. Membrane Proteins
4. Glycocalyx
5. Import, Export, Intracellular Transportation
6. Cell Wall Surface
B. Cytoplasm
C. Cytoplasmic Organelles
1. Endoplasmic Reticulum
2. Golgi Apparatus
3. Annulate lamellae
4. Mitochondria
5. Lysosomes
6. Centriole
7. Peroxisomes/Microbodies
8. Filaments
9. Microtubules
D. Cytoplasmic Inclusions
1. Pigments
2. Lipids
3. Glycogen
4. Crystals/Crystalloids
5. Secretory Granules
6. Vacuoles
E. Nucleus
1. Types of Nuclei
2. Nuclear Envelope
3. Nuclear chromatin
4. Nucleolus
5. Chromosomes
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III. SLIDE REVIEW
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APA REFERENCES
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FREEDOM WALL
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I. THE CELL
Histology
● The study of normal cells and tissues through the
use of a microscope
The Cell
● Fundamental unit of living organisms showing a
variety of functional specializations which performs
BATCH 2026
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all the activities necessary for the survival, growth
and reproduction of the organism.
Smallest living unit of an organism
All cells have three things in common no matter the
cell type:
○ Cell Membrane
○ Cytoplasm
○ Genetic material
Functional and structural unit of all organisms
The simplest organisms consists of a single cell
○ Bacteria
○ Algae
A. 2 Types of the Cell
1. Eukaryotic cell
● Presence of true nucleus surrounded by a nuclear
envelope
● Organisms whose cells consists of a cytoplasm and a
defined nucleus bounded by a nuclear membrane
○ Plants
○ Fungi
○ Animals
● Seen within the cytoplasm are different membraneenclosed organelles (nucleus and other special parts)
● More advanced complex cells such as those found in
plants and animals
2. Prokaryotic cell
● Do not have a nucleus and membrane-bound
organelles
● Absence of nuclear envelope
● Its nuclear substance is mixed with the rest of the
cytoplasm
○ E. coli
○ Cyanobacteria
● Have genetic material but not contained within the
nucleus
● ALWAYS unicellular (e.g., bacteria)
B. Parts of the Cell
Figure 1. The Cell
Wheater’s Functional Histology, 6th ed.
1. Plasmalemma/Cell membrane
● Outer/external limiting membrane (selective barrier)
● Separates the inside of a cell from its environment
● Serves as a dynamic interface between the internal
and external environment of the cell
2. Cytoplasm
● Jelly-like fluid
● The protoplasm outside of the nucleus which contain
various organelles and inclusion bodies
3. Nucleus
● Largest organelle
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Substance is referred to as the nucleoplasm
Bound by a membrane system called the nuclear
envelope
● Control center of the cell
● Contains DNA or genetic material
○ Dictates what the cell is going to do and
how it’s going to do it
● Chromatin is a tangled spread out form of DNA
found inside the nuclear membrane.
● When the cell is ready to divide, DNA condenses into
structures known as chromosomes.
● Contains nucleolus where ribosomes are made
○ Once the ribosomes leave the nucleus, they
will proceed to protein synthesis.
4. Endoplasmic Reticulum
● Membrane-enclosed passageway for transporting
materials, such as proteins synthesized by
ribosomes.
● Outside the nucleus, the ribosomes and other
organelles float around the cytoplasm.
● Ribosomes may wander freely in the cytoplasm or
are attached to the endoplasmic reticulum (ER).
a) Rough ER: has ribosomes attached to it
b) Smooth ER: NO ribosomes attached to it
5. Golgi Apparatus
● Receives proteins and other materials that emerge
from the ER in small vesicles
● As proteins move to the golgi body, they are
customized by folding to forms that the cell can use
or by adding other materials such as lipids or
carbohydrates.
6. Vacuoles
● Sac-like structures that store different materials
● Central vacuole stores water
7. Lysosomes
● Garbage collectors
● Takes in damage or worn-out cells
● Filled with enzymes that break down the cellular
debris
8. Mitochondria
● Powerhouse for both animal and plant cells
● Cellular respiration
○ Mitochondria make ATP molecules that
provide energy for all the cell’s activities.
● Cells that need more energy have more
mitochondria
9. Cytoskeleton
● Maintenance of shape
● Consists of:
○ Thread-like microfilaments are made up of
protein
○ Microtubules are thin hollow tubes
10. Chloroplast
● Found in plant cells which are photoautotrophic
○ Capture sunlight for energy
● Site of photosynthesis
● Appears green in color due to the green pigment
(chlorophyll)
11. Cell wall
● Outside of the cell membrane
● Shapes, protects and supports plant cells
● ANIMAL CELLS NEVER HAVE A CELL WALL
Figure 2. The Cell EM x16 500
Wheater’s Functional Histology
C adjacent cell ER endoplasmic reticulum F collagen fibrils
G golgi apparatus IS intracellular space L lysosome M mitochondrion
N nucleus NE nuclear envelope PM plasma membrane V transport
vesicles
C. Other Unique Structures of the Cell
1. Cilia
● Found in cells in the respiratory tract of humans
● Microscopic hairlike projections that trap inhaled
particles in the air, and expel them when you cough
2. Flagella
● Found In some bacteria
● Little tail that helps the cell move or propel
● Sperm cell is the only human cell with flagella.
II. ULTRASTRUCTURE OF THE CELL
A. Cell Membrane
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Outer trilaminar-appearing membrane surrounding the
cell
Selective barrier that regulates entrance and exit of
substances into the cell
Dynamic interface with external environment
Figure 3. Cell Membrane
1. 2 Models
1. Classical Model of Davson and Danielli
● Phospholipid bilayer between 2 layers of globular
proteins
○ Lipid center sandwiched by a coat of
protein on each surface
○ Also known as “lipoprotein sandwich”
● Trilaminar and lipoproteinous
Figure 4. Classical Model
2. “Fluid Mosaic Model” of Singer and Nicholson
● Membrane proteins are globular and float like an
iceberg in a sea of lipids
● In a dynamic state
● More acceptable model
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Fluid combination of phospholipids, cholesterol,
proteins, glycolipids, and glycoproteins that extend
from outward facing surface of membrane
○ Glycolipids = carbohydrates attached to
lipids
○ Glycoproteins = carbohydrates attached to
proteins
○ Proteins embedded within the lipid bilayer
act as channels for the selective passage of
particular ions and molecules
Wheater’s Functional Histology, 6th ed.
3. Membrane Proteins
1. Intrinsic protein
● Embedded within the bilayer
2. Transmembrane protein
● Spans the entire thickness of the membrane
3. Peripheral membrane protein (extrinsic)
● Attached to inner or outer membrane
Figure 7. Lipid Bilayer and Membrane Proteins
Wheater’s Functional Histology, 6th ed.
Figure 5. Fluid Mosaic Model
2. Phospholipid Bilayer
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Amphipathic or Amphiphilic
● Polar hydrophilic (“water-loving”) head
○ Directed outwards
○ Connected by phosphate bridges that
consist of glycerol conjugated to a
nitrogenous compound such as:
■ Choline
■ Ethanolamine, or
■ Serine
○ Phosphate = negatively charged
○ Nitrogenous compound = positively charged
● Non-polar hydrophobic (“water-hating”) tail
○ Directed inwards
○ Consist of 2 long chains of fatty acids, each
covalently linked to the glycerol component
of the polar head
■ Straight-chain saturated fatty acid
■ Unsaturated fatty acid kinked
(bent) at unsaturated bond
Sphingomyelin
● Important and plentiful phospholipid
Cholesterol molecules
● Present in between bilayer
● Amphipathic and have kinked formation
○ Promote flexibility of membrane by
preventing close packing of hydrophobic
tails
○ Stabilize and regulate fluidity of
phospholipid bilayer
● Present in almost 1:1 ratio with phospholipids
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Membrane proteins are attached to the inner or outer
membrane leaflet by weak non-covalent bonds to other
proteins or lipids
Functions
○ Cell-cell adhesion
○ Cell-matrix adhesion
○ Intercellular signaling
○ Formation of transmembrane channels for
transport of materials into and out of cell
a Plasmalemma/plasma membrane is composed of a
phospholipid bilayer and its membrane proteins are
embedded in a “mosaic formation/configuration”
b Protein molecules on external and protoplasmic surfaces
of the plasmalemma give an asymmetrical appearance to
molecular structure
c Polysaccharide chains from the surface of the
plasmalemma conjugate with glycoproteins and
glycolipids, forming an outer coating called the glycocalyx
which vary in thickness and different cell types
4. Glycocalyx
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Glycoprotein and polysaccharide covering of external
surface of cell membrane
Imparts special identity to each cell type
Plays a vital role in histocompatibility
Involved in:
○ Cell recognition phenomena
○ Formation of intercellular adhesions
○ Adsorption of molecules to cell surface
Provides mechanical and chemical protection for plasma
membrane
Figure 8. Glycocalyx
Figure 6. Phospholipid Structure
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Figure 9. Cross section of cell membrane (EM)
Figure 10. Long section electron micrograph of microvilli of
the small intestine. Glycocalyx is bound to plasmalemma of
microvilli.
5. Import, Export, Intracellular Transportation
1. Passive Diffusion/Transport
● Dependent on:
○ Presence of concentration gradient across
the membrane
○ Size and polarity of molecule
● Movement of substances into or out of the cell
without use of energy
● Diffusion
○ Movement of molecules down the
concentration gradient across the plasma
membrane from an area of high to low
concentration
● Examples
○ Lipids and lipid-soluble molecules (estrogen
and testosterone), gases pass freely
through lipid membranes
○ Unchanged but polar small molecules
(water and urea) diffuse slowly
○ Charged molecules (Na+ and K+) diffuse
very slowly
2. Facilitated Diffusion
● Strictly passive
● Moving polar/charged substances (water, ions,
glucose, amino acids) along electrochemical gradient
● Requires the presence of protein carrier
○ Pores or channels
■ From water-filled channels across
the membrane through which
selected molecules or ions can
pass depending on the
concentration, size and electrical
charge
■ Ex. Aquaporins allow water to
cross membranes at a faster rate
than diffusion alone. Some
facilitated diffusion pores are
gated wherein they open or close
depending on different
physiological conditions.
○ Transporter or carrier
■ Binds particular molecule/ion and
undergoes change in conformation
3. Active Transport
● Independent of the electrochemical gradient
● Operates against extreme electrochemical gradient
Movement of substances into or out of the cell with
the use of energy (ATP) through transport proteins
that undergo conformational change
● Use Pumps → forces ions/molecules from an area of
low to high concentration/ against the concentration
gradient
● Example: Continuous movement of sodium out and
potassium in the cell by Na & K ATPase pump
○ ATP is converted to ADP to generate the
energy required
4. Bulk Transport
● Transport of large molecules or small particles into,
out of or between compartments when cell is
mediated by subcellular transient membrane-bound
vesicles
○ Transport vesicles formed by the assembly
of protein “coat” leading to the budding of
a section of the membrane which is pinched
off to form a vesicle.
● Vessels are taken in the cell via endocytosis (endo=
inside) or exocytosis (exo= outside)
5. Transmembrane signaling
● Various ways by which signals cause plasma
membrane to deliver information to cell
● Examples
○ Neurotransmitters at nerve synapses bind
to ion channels in the postsynaptic
membrane, allowing ions to enter the cell
to initiate membrane depolarization
○ Lipid-soluble molecules (estrogen) diffuse
the plasma membrane to bind to
intracellular receptor
6. Osmosis
● Movement of water across the plasma membrane
through specialized proteins called aquaporins
NOTE: The video (Ricochet Science) supplemented in the
recording stated that diffusion, facilitated diffusion, and
osmosis fall under passive transport since no energy is
needed for the molecules to move in or out of the cell
membrane.
6. Cell Wall Surface
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Functions
○ Filtration barrier
○ Allows sudden changes in ion permeability in
response to changes in electrical potential
○ Receptops site for hormones & enzymes
○ Cell Recognition (GLYCOCALYX)
Processes that occur on the cell surface:
1. Endocytosis
● Engulfing of materials into the cell via the enclosure
of local invaginations of the plasma membrane then
pinching off to form a membrane-bound vesicle in
the cell
a. Pinocytosis
○ “Cell drinking” of fluids, solutes, and/or
relatively small particles
b. Phagocytosis
○ “Cell eating”
○ Engulfing relatively large particles (ex.
Bacteria or Food particle)
c. Receptor-mediated endocytosis
○ Binding of molecules to specific receptor
proteins embedded in a coated pit on the
plasma membrane
○ When enough molecules are attached to
the receptors, the coated pit deepens,
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seals, and is incorporated as a form of
vesicle
C. Cytoplasmic Organelles
1. Endoplasmic Reticulum
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Figure 11. Endocytosis
Wheater’s Functional Histology, 6th ed.
Figure 12. Phagocytic white blood cell engulfing bacteria
Wheater’s Functional Histology, 6th ed.
B bacteria Pp pseudopodia Ps phagosomes Ly1 lysosomes
2. Exocytosis
● Moving of materials out of the cell
● Excretory granule is membrane bound and fuses
with the cell membrane to release its contents to the
outside of the cell
Figure 13. Exocytosis of typical protein-secreting cells from
the pancreas
Wheater’s Functional Histology, 6th ed.
Consists of an anastomosing network of
intercommunicating channels and sacs formed by a
continuous membrane
1. Granular/Rough ER (RER)
● Site of protein synthesis (ribosomes)
● Interconnecting network of membranous tubules,
vesicles, and flattened sacs (cisternae)
● Most typical
● Appears rough under electron microscopy because
its membrane surface is studded by evenly-spaced
ribosomes
● Ribosomes adhere to the outer membrane of the
nuclear envelope which is continuous with the RER
● RER may also be connected with the SER
● Function:
○ Synthesis of secretory protein and its
storage within the intracisternal space
Figure 14. Rough Endoplasmic Reticulum
Wheater’s Functional Histology, 6th ed.
2. Smooth ER (SER)
● Site of lipid biosynthesis
● Membranes are also arranged in an anastomosing
network of tubules
● Non-granular
● Cisternae are more tubular
● May also connect with the ER, the plasmalemma, and
the Golgi complex
● Functions:
○ Membrane synthesis and repair: where
cholesterol
and
phospholipid
are
synthesized
○ Striated muscle: sarcoplasmic reticulum
○ Endocrine cells: biosynthesis of steroid
hormone
○ Liver cells: rich in cytochrome P450;
detoxification
of
noxious/harmful
substances
(e.g.
drug/alcohol)
and
metabolism of glycogen
○ Intestinal villi: synthesis of neural fats
○ Parietal cells of the stomach: formation of
HCl
B. Cytoplasm
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1.
2.
The ground substance (hyaloplasm) is subdivided into:
Endoplasm
● Usually in sol phase and manifests active streaming
● Cellular components are carried along by directed
movements
Exoplasm
● Usually in gel state
● Relatively free of cellular components
● Occupies the periphery of the plasmalemma
Figure 15. Smooth Endoplasmic Reticulum
Wheater’s Functional Histology, 6th ed.
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2. Golgi Apparatus
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Membrane-bound organelle that is made up of a series of
flattened, stacked pouches called cisternae
Important site of protein synthesis, lipid glycosylation, and
site of synthesis of many Glycosaminoglycans (GAGs) that
form the extracellular matrix
Function:
○ Packaging of secretory products in a membrane
capable of fusing with the plasma membrane
during exocytosis
■ In granular cells: site of accumulation
and concentration of secretory products
■ Site of sulfation of cells that secrete a
mucopolysaccharide/ glycoprotein
■ Concentrates and packages hydrolytic
enzymes in cells (lysosomes)
System of stacks of 4-6 saucer-shaped cisternae with
concave (maturing/trans face) facing the nucleus and a
(forming/cis face) adjcent to RER
Difference of CIS vs. TRANS face
○ CIS face = vesicles leave ER and fuse with the
Golgi apparatus
○ TRANS face = vesicles exit Golgi apparatus
4. Mitochondria
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Mobile “Power plant or powerhouse of the cell”
○ Site of aerobic respiration
Appearance: slender rods, cigar shaped organelle
Vary in size, shape and number
Self-replicating
Present in all eukaryotic cells
Enclosed by two layers of smooth membranes
Cristae mitochondriales: infoldings that increase the
surface area of the mitochondria
Mitochondrial spaces formed by the mitochondrial
membrane
○ Large Intercristal space
○ Small intramembranous space
Inner membrane: Contains minute club shaped particles
called elementary particles that participate in the
formation of ATP
Mitochondrial matrix
○ Amorphous, finely granular with small dense
intramitochondrial granules
○ Circular form of DNA and RNA (for selfreplication) is found inside
Functions of the Mitochondria
○ Main Function: ATP Synthesis as cell energy
source
■ Attached to membranes are the
respiratory
and
phosphorylating
enzymes
■ Kreb’s citric cycle, protein and lipid
synthesis cycles are found inside the
matrix
○ Calcium accumulation
○ Nucleic acid and protein synthesis
○ Fatty acid oxidation
Figure 16. Cis and Trans Golgi network
Wheater’s Functional Histology, 6th ed.
Figure 19. Mitochondria
5. Lysosomes
Figure 17. Golgi Apparatus
Wheater’s Functional Histology, 6th ed.
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3. Annulate lamellae
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Visible only with electron microscopy
Parallel array of cisternae with small pores at regular
intervals
Presence of diaphragms closing the pores
Unknown functional significance
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Figure 18. Annulate lamellae
Small membrane bound bodies that vary in shapes and
sizes
Contain hydrolytic enzymes called acid hydrolases for
intracellular digestion
Two types of lysosomes:
○ Primary Lysosomes: Resting lysosomes
○ Secondary Lysosomes: Actively engaged in
digestion
Functions:
○ Site of foreign body destruction for cellular
defense
○ For the normal replacement of cellular
components and organelles
○ Has an important part in the metabolism of some
substances found in the body
Function concepts
○ Enzyme synthesis occurs in the RER and is packed
in the golgi complex
○ Heterophagosome:
where
bacteria
are
destroyed
○ Autophagosome: involved in digestion, along
with the RER and mitochondria
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Residual body contains
undigested molecules
remnants
of
all
Figure 22. Peroxisomes/ Microbodies
Figure 20. Lysosomes
8. Filaments
NOTE: Both heterophagosomes and autophagosomes are
secondary lysosomes and the product of their digestion can
be excreted.
Table 1. Types of Filaments
6. Centriole
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Nine groups of longitudinally oriented parallel sub-units
Each of the nine groups consists of 3 microtubules aligned
and fused together making it look like they appear as
three circles in a row
Diplosome
○ A pair of short centriole rods associated with cell
division
○ Usually adjacent to the nucleus
○ Self-duplicating
○ Electron Microscopy: Hollow cylinder, with one
end closed, and one end open
○ Long axis view: Positioned perpendicular to each
other
○ Function:
■ Has an important role in cell division
■ Essential in cilia and flagella formation
■ Serves as the basal bodies and sites of
epithelial origin
Diameter
Contractility
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Less than 8 nm
8-12 nm
Contractile
Non-contractile
Functions:
○ Maintain cellular shape of the cytoskeleton
○ Provide resilience to forces that alter the shape
as seen in “wear and tear” epithelium
○ These are regular components along with
microtubules in nerve cells
○ For supportive intracellular network and
transmission of forces among adherent cells
○ Seen in sites of adhesions between adjacent cells
of epithelial systems
Figure 23. Microfilaments
7. Peroxisomes/Microbodies
Membrane-bound bodies that sometimes contain a
crystalloid
Enzymes (catalases) are found inside and these are for
hydrogen peroxide destruction
Function:
○ Beta oxidation of certain long chain fatty acids
○ Helps in the synthesis of plasmalogens (myelin
sheath lipids)
○ Essential in some steps in bile synthesis of the
liver
Intermediate/
Tonofilaments
Mupas-Uy, J. (2022). Recording of the Ultrastructure of the
cell
Figure 21. Centrioles
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Microfilaments
9. Microtubules
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Widely occurring, slender, cylindrical structures
Appears as a circle composed of 13 globular subunits
○ Composed of 9 doublets with a central pair
Seen in cilia, flagella, mitotic spindle, and centrioles
Functions:
○ Important element of the spindle apparatus in
dividing cells, forming the mitotic spindle
○ Form the cores of cilia and the flagella of sperm
cells (Nine doublets with a central pair)
○ Play a role in maintaining diverse cell shape
Cytoskeleton
○ Difficult to identify with routine light microscopy
○ Immunostaining techniques must be used
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Figure 24. Microtubules
With increasing age, it accumulates as a yellowish
brown granule commonly seen in cells of older
individuals.
Referred to as the “Wear & tear” or “age pigments”
Figure 27. Micrograph of lipofuscin
Wheater’s Functional Histology, 6th ed.
D. Cytoplasmic Inclusions
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Lifeless accumulations of metabolites or cell products are
regarded as dispensable and often temporary
constituents, which are not essential for the survival of the
cell.
2. Lipids
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Round, clear areas (unstained vacuoles) in the cytoplasm
because the solvents extracted the lipids
Appear as black spherical droplets of varying sizes with
osmium tetroxide
1. Pigments
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Materials with natural color that do not require staining
by dyes.
A. Exogenous pigment
● Formed outside of the body
● Examples: carotenes, dusts (carbon), minerals (lead &
silver); those used for tattooing
B. Endogenous pigment
● Formed within the body
● Examples: melanin, hemosiderin, lipofuscin, bilirubin
Melanin
● Dark brown/black pigments found in melanocytes
containing melanosomes in the epidermis
● Responsible for giving the skin its color
● Also found in the brain (substantia nigra)
Figure 28. Lipids
Wheater’s Functional Histology, 6th ed
3. Glycogen
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Non-membrane bound spherical aggregates of lipid
Commonly found in the liver
Appears as full cytoplasmic particles under an electron
micrograph
Two (2) types:
○ Beta particles - appear as dense, irregular,
spherical bodies
○ Alpha particles - appear as rosette-like
aggregates of larger size (glycogen rosettes)
Figure 25. Melanin
Figure 30. Glycogen
Figure 26. Melanin in Substantia Nigra
Wheater’s Functional Histology, 6th ed.
Lipofuscin
● Represents an insoluble degradation product or
organelle turnover
Figure 31. Alpha and beta particles of glycogen
under electron micrograph
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4. Crystals/Crystalloids
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Proteinaceous
Not bound by membranes
Found in Sertoli cells and interstitial cells of Leydig
Electron Microscopy: Shows a regular lattice pattern
under an electron micrograph
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Archive of the cell; repository of hereditary
factors
Source of rRNA, mRNA, and tRNA
1. Types of Nuclei
1. Vesicular nucleus
● Larger, paler-staining nucleus
● Highly-stained nucleolus giving a “fish-eye” or an
“owl’s-eye” appearance
● Found in liver cells or nerve cells
2. Pyknotic nucleus
● Seen in dying cells
● Heterochromatin is extremely dense
3. Chromatic nucleus
● Small, darkly-stained nucleus with more condensed
chromatin
● Commonly seen in fibroblasts and fibrocytes
Figure 32. Crystals
Figure 35. Types of nuclei
5. Secretory Granules
NOTE: The shape, appearance, and location of the cell nuclei
can be very helpful in identifying particular cell types.
Membrane-bound
With limiting membranes
Zymogen secretory granules are seen as large dense
granules
2. Nuclear Envelope
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Figure 33. Secretory granules
Encloses nucleus with a perinuclear space in between
Outer limit of nucleus; separates nucleus from cytoplasm
About 40nm thick and 7x thicker than plasmalemma
Consists of a lipid bilayer membrane enclosing a narrow
perinuclear space that communicates with the cisternae
of the reticulum
Inner and outer nuclear membranes have the typical
phospholipid bilayer structure but contain different
integral proteins
6. Vacuoles
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Storage cavities
Figure 34. Vacuoles
E. Nucleus
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Largest organelle
Most obvious feature of the cell
Contains the genetic material of the cell (DNA) arranged
in the form of chromosomes
Found in all cells except in RBCs and platelets
Stains blue (basophilic) because of its nucleic acids and
basic protein
Varies in shape, size, and number
○ Can be spherical, lobated in neutrophils, cupshaped or indented;
○ Usually single (but binucleated in liver cells); can
be multiple in skeletal muscles and osteoclasts
Major Functions:
1. Outer lipid layer
● Has ribosomes on its cytoplasmic surface
● Continuous with lumen of endoplasmic reticulum
(specifically RER)
● The intramembranous space is continuous with the
lumen of the ER
2. Inner lipid layer
● Contains nuclear lamina
○ A layer of intermediate filaments that
consists of lamins that links the inner
membrane to heterochromatin
● Contains numerous nuclear pores with a small dense
granule
○ A pore complex is seen in each pore
■ At the margins of which the inner
and outer membrane become
continuous
○ A short cylinder formed by eight regular
subunits with a central granule.
○ Important in the exchange of materials
between the nucleoplasm and the
cytoplasm
■ Permits and regulates the exchange
of metabolites, macromolecules
and other substances
○ Its permeability varies with nuclear activity.
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1. Dense Fibrillar Component (DFC)
● Contains newly synthesized pre-RNA
2. Fibrillar Centers (FC)
● Site of RNA synthesis
3. Granular Component (G)
● Site of ribosome assembly
Figure 36. Nuclear envelope and related structures
3. Nuclear chromatin
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Nuclear material that contains DNA and protein
Structural manifestation of chromosomes in
Interphase
1. Heterochromatin
● The condensed, coiled part; metabolically inert
● Inactive chromatin found in irregular clumps
2. Euchromatin
● Dispersed, less coiled regions
● Active in protein synthesis
Figure 39. Nucleolus and its regions
5. Chromosomes
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Humans have 44 chromosomes in a pair of sex
chromosomes
Sex Chromatins
○ Possible to determine the genetic sex of an
individual by light microscopy.
○ Small visible mass in the nucleus of the
buccal epithelium (Barr bodies)
○ In female: neutrophil granular leukocytes
(drumstick appendage)
Figure 37. Nuclear chromatins
Yellow pointed structure = heterochromatin
III. SLIDE REVIEW
SLIDE 1: PARTS OF THE CELL
Figure 38. Euchromatin and Heterochromatin
Heterochromatin - dark and at the periphery; Euchromatin - lighter
4. Nucleolus
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A round body eccentrically located in the nucleus
Rich in RNA and basic proteins
Site of ribosomal RNA synthesis and tRNA processing
Newly discovered functions include control of cell
cycle and stress response
Not membrane bound and may change appearance
depending on cell activity
Consists of an aggregate of ribosomal genes,
ribosomal RNA, ribonucleoprotein, and ribosomal
proteins
Intensely basophilic due to presence of
ribonucleoproteins
Regions of Nucleolus:
Plasmalema
● Plasma Membrane
● Thin Layer enclosing a cell’s cytoplasm
Nucleus
● Closed organelle that contains chromosomes
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Nucleolus
● Largest structure in the nucleus
● Site of ribosome biogenesis
Euchromatin
● Lightly Packed form of chromatin (DNA, RNA Protein
) that is rich in genes
● Invovled in active transcripton of DNA to mRNA
Heterochromatin
● Located at the nuclear periphgery
● Highly condensed compared to auchomatin
Michrocondrion
● Double membrane bound organelle
● Generate cell supply of ATP or chemical energy
Gogli Body
● Fucntions to packages the proteins to membrane
bound vesicles inside the cells before it is
transported to different locations
Endoplasmic Reticulum
● Production of proteins
Secretory Granules
Contains the bilirubin pigment, which is
produced during the breakdown of RBCs →
production of bile
Peripherally Located
Example:
● Osteoclast
SLIDE3: MEGAKARYOCYTE
SLIDE 2: APPEARANCES OF THE NUCLEUS
Multilobulated and Bilobulated
●
●
Multilobulated (ie. segmenters)
Bilobulated (ie. eosinophil)
Peripherally Located
Megakaryocyte
● Giant cell with large irregularly lobed polyploid
nucleus (yellow arrow)
● Occurs in small numbers in the bone marrows
● Give rise to platements via fragmentation of its
cytoplasm
SLIDE 4: TYPE OF NUCLEUS
Example:
● Striated muscle
○ Peripherally located nucleus
Chromatic Nuclei
Chromatic Nucleus
● Small darkly stained nucleus
● More condensed chromatin
● Seen in fibroblast and fibrocytes
Example:
● Hepatocytes
○ Livers of the cell
○ Some of the nucleus are binucleated
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●
●
●
Cigar-shaped organelle
Self-replicating
Present in all eukaryotic cells
RER with ribosomes
● Presence of ribosomes making it look rough in
appearance
● Composed of interconnecting networks of
membranous tubules, vesicles, and flattened sacs
Vesicular Nucleus
● Seen in the neuron
● Described as larger, paler staining nucleus with a
highly stained nucleolus
● Fish eye or owl’s eye appearance
Pyknotic Nucleus
● Seen in dying cells
● Heterochromatin is extremely dense
Lysosomes
● Primary lysosome
○ Aka resting lysosome
○ Homogenous, dense
○ Membrane-bound organelle packed with
acid hydrolases
● Secondary lysosome
○ Active lysosome
○ Composed of a combination of primary
lysosome that are fused with phagosomes
in which lysis takes place through the use of
the hydrolytic enzymes
SLIDES 5: ORGANELLES
SLIDES 6: TYPES OF FILAMENTS
Microtubules
● 24 mm in diameter
● Made up of globular protein subunits such as alpha
and beta tubulin which polymerizes to form a hollow
tube
● There are 13 tubulin molecules that make up a circle
Rough Endoplasmic Reticulum (RER)
● Studded with ribosomes
Centriole
● Has a circular outline
● Wall that is composed of 9 groups of longitudinal
parallel subunits
● Each of the 9 groups consist of 3 microtubules
aligned and fused together so they appear as 3
circles in a row
Mitochondria
● Mobile power plant of the cell
● Appear as slender rods
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SLIDES 7: PIGMENTS
Microfilaments (Actin filaments)
● Protein filaments in the cytoplasm of eukaryotic cells
that forms part of the cytoskeleton
● This slide shows a smooth muscle cell with
cytoplasmic microfilaments
Melanin
● Seen in the epidermis
Lipofuscin
● Found in cardiac muscle
● Yellowish brown pigments found in the skin of older
individuals
● Wear and tear or age pigment
APA REFERENCES
●
●
Intermediate filaments
● Forms the true skeleton of the cell
● Tonofilaments
○ Intermediate filaments found in the
cytoplasm of epithelial cells
● There are different subtypes of intermediate
filaments found in different cell types and is typical
of that type of cell
○ In the epithelial cells: keratin
○ In the mesenchyme cells: vimentin
○ In the muscle cells: desmin
○ Neurons: neurofilament
○ Nuclear lamina: lamins
●
Mupas-Uy, J. (2022). Recording of the Ultrastructure of
the cell
Young, B., Woodford, P., & O'Dowd, G. (2014). Wheater's
functional histology E-book: A text and colour atlas.
Elsevier Health Sciences.
Batch 2025 transcript
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FREEDOM WALL
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