2. Introduction to Histology and
Histological techniques.
● Objectives:
At the end of the lecture you should be able to:
o 1. Know the organization and components of the
human body and the principle tools used to study its
microscopic structures, i.e. the different techniques
for preparation and staining of tissue sections and
different types of microscopes.
o 2. Explain the significance of tissue culture
techniques to the study of live cell systems.
3. THE CELL
● At the end of the lecture you should be able
to:
o 1. Know the structure of the different
components of the cell at both light and electron
microscope levels and give their functional
significance.
o 2. Correlate between the predominance of cell
organelle and the function of the cell.
4. Histology: is the study of the cells and
tissues.
Cytology: is the study of the structure
and function of the cell.
The cell: every cell consists of cytoplasm
surrounded by membrane and contains
nucleus. Suspended within the cytoplasm;
are the organelles and inclusions.
5. The cell is surrounded by a membrane and contains:
(I) Nucleus
(II) Cell organelles
(III) Cell inclusions
Suspended within
the cytoplasm
7. The Nucleus
1. Nucleolus: is the center for the synthesis of
ribosomal RNA
2. Nuclear membrane (envelope):
It surrounds the nucleus & is formed of inner
and outer membranes.
The space between the two layers is named
perinuclear cisterna
The nuclear pores are perforations in the
nuclear envelope.
3. Chromatin: is the genetic material of the cell
(DNA). It is formed of:
Heterochromatin: inactive form
Euchromatin: active form
4. Nucleoplasm (Karoplasm):
It contains macromolecules and nuclear particles
8. (II) Cell organellesoOrganelles are
specialized parts of
living substance
within cells.
oOrganelles are
divided into:
(A) Membranous
(B) Non membranous
9. (A) Membranous organelles:
surrounded by membrane; including:
oPlasma membrane
oMitochondria
oEndoplasmic reticulum
➢Smooth (SER)
➢Rough (RER)
oGolgi apparatus
oPeroxisomes
oLysosomes
oEndosomes
What are the Membranous orgnales and talk
about one of them ??
10. B) Non membranous organelles:
oCytoskeleton of the cell:
➢Microtubules
➢Filaments
oCentrioles
oRibosomes
For example: myosin and actin in muscles
Has relationship in cell division
11. Cell Membrane
• LM: Not visible
• EM: It has trilaminar
appearance = it appears
as 2 electron dense
lines and a clear space
in between.
• Molecular structure:
Light microscope
Electron microscope
Cell membrane 2 layers and clean space in between
But in Electron microscope (EM) looks like it has 3 layers
12. Cell Membrane Molecular Structure
● The cell membrane consists mainly of lipid and protein and
other molecules.
1. lipid is mainly phospholipid (bimolecular) lipids
present in the central part of the cell membrane. Each
lipid layer is formed of:
Hydrophilic head: attached to water.
Hydrophobic tail: no affinity to water.
2. Protein molecules: constitute about 60-70% of
membrane mass.
a. Peripheral proteins attached to the
heads.
b. Integral proteins throughout the
phospholipid.
3.Other molecules:
A. Cholesterol
B. Carbohydrate: glycoprotein and glycolipid which form
the cell coat (glycocalyx)
Carbohydrates chain
calls glycoliped
13. Cell Membrane Function
● Function:
➢ Exchange of materials.
➢ Receptor function.
➢ Conduct impulses.
➢ Protection and cell recognition
What are the function of membrane ??
14. Mitochondria
● It is the main source of energy
in the cell.
● They can divide by binary
division.
● The inner membrane is highly
folded (cristae) and the outer
membrane is smooth.
● The mitochondrial lumen is filled
with matrix, which contains
mitochondrial granules.
● Function:
● It is the powerhouse of the cell.
● It contains enzymes of the Kreb’s
cycle.
15. Endoplasmic Reticulum
RER and SER
● It is formed of anastomotic network of
tubules and vesicles.
There are two types:
1. Smooth endoplasmic reticulum
(SER)
● Its lumen is continued with the lumen
of RER.
Function:
● Steroid and lipid synthesis
● Detoxification of drugs.
● It may be involved in glycogen
synthesis.
● Form sarcoplasmic reticulum in
skeletal muscle.
SER
RER
SE
R
16. Endoplasmic Reticulum
RER
2. Rough endoplasmic reticulum
(RER)
● The outer membranes of
these saccules are richly
studied with ribosomes.
● The cells rich in (RER) stains
deeply with basic dye
(basophilia) i.e. blue color.
Function:
● Protein synthesis and
modification
RER
RE
R
17. Golgi Apparatus
It is formed of a stack of parallel
flattened cisternae or sacs, each
cisternae has 2 faces:
● Cis Golgi or forming face
(convex) towards nucleus.
● Trans Golgi or mature face
(concave)towards
plasmalemma.
• Transport vesicle.
• Condensing vacuoles.
• Secretory vesicle.
Golgi Apparatus
Contents of Golgi Apparatus:
18. Golgi Apparatus Function
● Function:
➢ It is concerned with secretory
activity of the cell.
➢ Modification and sorting of proteins
manufactured on RER.
➢ Has a role in membrane
biosynthesis.
21. Lysosomes• They have different sizes and shapes.
• They have hydrolytic enzymes.
• Function:
Digestion of macromolecules, microorganisms, cellular
debris and excessive organelles
• Types:
1- Primary lysosomes recently formed and don`t contain digested
material.
2- Secondary lysosomes:
● phagosome
● auto phagic vacuole
● pinocytotic vesicle
3- Residual body lysosome that digested materials.
23. Peroxisomes
Perixosomes: (Microbodies = spherical bodies)
• They contain oxidative enzymes that are responsible
for break down of H2O2 (Hydrogen peroxide), which
is a toxic substance.
Endosomes
•They are system of tubules and vesicles
•Prepare contents for the destruction by lysosomes
It’s an example
of Free radicals
25. (B) Non- Membranous organelles:
1. Cytoskeleton:
•They maintain the shape of the cell.
•They include:
a.Microtubules formed of tubulin
b.Filaments = microfilaments.
-Thick filaments (Myosin)
-Intermediate filaments (Tonofilament)
- Thin filament (Actin)
• Function:
-Shape and movement of the cell, cilia, flagella
-Transport of vesicles and chromosomes
27. 2- Centriole: is involved in cell division.
3. Ribosomes:
•They are granules consist of 2 subunits: large and small.
•They are attached to (RER) by their large subunit.
•There are two types of ribosomes:
Attached ribosomes:
•Are attached to RER by their large subunits.
Free ribosomes:
•They circulate freely in the cytoplasm.
•Polysomes: are ribosomes forming circled strings
•Functions:
-Attached ribosomes are responsible for protein secretion to outside the
cells (proteins for export).
-Free ribosomes are responsible for protein synthesis inside the cells.
29. (III) Cell Inclusions
● These are the non- living structures of the cell:
● Pigments:
● Melanin
● Lipofuscin
● Haemosidrin
● Lipid = Fat droplets.
● Glycogen : stored in liver cell and muscle.
