الله بسمالرحيم الرحمن

INTRODUCTION TO HISTOLOGY

HISTOLOGY(MICROSCOPIC ANATOMY)

Definition.

Light Microscope (L/M)

• 1- Illumination.• 2- Magnification.• 3- Resolution. N.B. Resolving power ( It is the least distance between 2 particles at which they will appear separated). R.P. for L/M is 250 nm

Light microscope

STAINING FOR L/M

Staining with Hematoxylin and Eosin

(H&E) or (Hx&E):

Basophilic structures.

Acidophilic structures.

(B) Electron microscopy:

1-Transmission E/M: Resolving power 0.2 nm.

* Electron-dense structure

**Electron-lucent structure

2-Scanning E/M: Resolving power 10 nm.

Transmission Electron Microscope

Scanning Electron microscope

THE CELL

THE CELL NUCLEUS(INTERPHASE NUCLEUS)

Shape of nuclei

Dark Nucleus(Deeply-stained nucleus)

Vesicular (open face) Nucleus

L/M:Appearance (Type):

- Light nucleus (vesicular) (open face)

- Dark nucleus (deeply-stained)

Number: 1, 2, or more.

Position: Central, eccentric, peripheral, basal.

CELL NUCLEUS)Interphase Nucleus(

Cell Nucleus

• L/M (cont.):Size:

Small, medium, large ) Nucleus/cell ratio(

Shape: e.g. Rounded, oval, rod-shaped.

Nucleus (E/M diagram)

RER-------

Hc

Nucleus (Electron Micrograph)

PRACTICAL

Nuclear pores

PRACTICAL

Cell Nucleus(Interphase nucleus)

E/M:(1) Nuclear envelopeInner nuclear membrane.

Outer. " " Nuclear pores.Nuclear pore complex.Perinuclear cisterna.

Nuclear lamina. N.B. Rough Endoplasmic reticula (Relation with,).

)2 (Chromatin: ( Classification ):According to Metabolic activity :

a- Euchromatin(Extended chromatin) b- Heterochromatin(Condensed chrom.)

According to Position: a- Peripheral chromatin.

b- Nucleolus-associated chromatin. c- Chromatin islands.

Nucleolus (E/M)

)3 (Nucleolus: L/M: 1-5 basophilic bodies

E/M: 1- Pale-staining fibrillar center.

2 -Pars fibrosa: containing rRNA (nRNA)

being transcribed.

Nucleolus (cont.):

3 -Pars granulosa: maturing ribosomal subunits are assembled.

4 -Nucleolar matrix.

N.B. Nucleolus is a non-membranous structure.

Function of nucleolus: rRNA synthesis.

NUCLEOPLASM

• 1- Nuclear matrix.

• 2- Ribonucleoprotein.

• 3- Interchromatin granules.

• 4- Perichromatin granules.

CYTOPLASM

(1) Organelles.

(2) Inclusions.

(3) Cytosol.

Cytoplasmic organelles1- Cell Membrane.

2- Ribosomes.

3- Endoplasmic Reticulum.

4- Golgi Apparatus.

5- Endosomes

6- Lysosomes.

7- Peroxisomes.

8- Mitochondria.

9- Cytoskeleton.

10-Centrioles.

11-Cilia & flagella.

12-Filaments (thin f., intermediate f., thick f.).

Cytoskeleton

1- Thin Filaments (actin filaments).

2- Intermediate Filaments.

3- Microtubules.

Specializations of cellmembranes

(1) Microvilli.

(2) Cilia.

(3) Intercellular junctions.

Cytoplasmic Inclusions

1- Glycogen.

2- Lipids.3- Pigments: e.g. lipofuscin pigments, melanin.

4- Crystals.

5- (Secretory granules).

CELL MEMBRANE(PLASMALEMMA)

Cell Membrane(Plasmalemma)

CELL MEMBRANE & GLYCOCALYX

GLYCOCALYX (CELL COAT)

MICROVILLI

MITOCHONDRIA

PRACTICAL

ENDOPLASMIC RETICULUM

ROUGH ENDOPLASMICRETICULUM

RER & SECRETORY GRANULES

GOLGI APPARATUS

LYSOSOMES

CILIA

CILIA

CILIA & CENTRIOLES

CENTRIOLES

CENTRIOLES

MICROTUBULES& ACTIN FILAMENTS

DISTRIBUTION OF MICROTUBULES IN INTERPHASE CELLS

• 1- Cytoplasmic microtubules.

• 2- Cilia.

• 3- Flagella.

• 4- Centrioles.

Glycogen granules in hepatocyte

INTERCELLULAR JUNCTIONS

INTERCELLULAR JUNCTIONS

(1) Occludent junction.

(2) Adherent junction.

(3) Gap junction (Nexus).

OCCLUDENT JUNCTION(TIGHGT JUNCTION)

DESMOSOMES(Macula adherent junctions)

GAP JUNCTION (NEXUS)

JUNCTIONAL COMPLEX