بسم الله الرحمن الرحيم

By Prof. Dr. Nahed Zohdy Professor of Histology & Cell Biology The cell By Prof. Dr. Nahed Zohdy Professor of Histology & Cell Biology

About this Lecture Cytoplasm: Structure Organelles Ribosomes ER Golgi apparatus Lysosomes Mitochondria

Haematoxylin and Eosin (H&E) Haematoxylin is a basic violet stain. Eosin is an acidic pink stain. Acidophilic structure= A structure that has affinity to stain with acidic dyes = basic in nature………So it stains pink with eosin Basophilic structure= A structure that has affinity to stain with basic dyes = acidic in nature……… So it stains violet with haematoxylin

The cytoplasm Composed of: 1- Cytosol: jelly like fluid matrix, its primary component is water 2- Organelles 3- Inclusion 4- Cytoskeleton cytoplasm Nucleus

Organelles Little organs: - Living structures Types: - Metabolicaly active - Perform certain functions - Permenant - Present in all cell types Types: - Memberanous organelles Non-membranous organelles

Ribosomes - Non-membranous organelles - Chemical nature: nucleoproteins consist of proteins conjugated with ribosomal RNA (rRNA) Structure: LM: By H&E stain: can not be seen if large in number they impart Cytoplasmic basophilia.

EM: 2 subunits: Electron dense granules Small subunit (RNA+30 P) large subunit (2RNA+40 P)

Types of ribosomes Free Attached Solitary Polysomes

Polysomes - Clusters of ribosomes connected by mRNA thread & producing identical proteins mRNA ribosomes Free protein in cytoplasm

Attachment of ribosmes to the rER

EM of attached ribosomes

Function of ribosomes Ribosomes are the sites of protein synthesis: Solitary: reserve Polysomes: proteins used by the cell Attached: proteins for secretion outside the cell

Endoplasmic reticulum - Membranous organelle - Network of interconnecting tubules and cisternae

Endoplasmic reticulum Rough (rER) Smooth (sER)

rER sER Cyto. basophalia LM Cyto. acidophilia

rER sER EM -Interconnected branching tubules -Interconnected parallel -Lacks ribosomes- -No connection with nucl. -Interconnected parallel cisternae -Has attached ribosomes -Connected to nuclear m.

rER sER EM Interconnected cisternae Interconnected tubules Has attached ribosomes Interconnected tubules Lacks ribosomes

rER sER Function Participates in protein synthesis. 1- Lipid synthesis (fatty acids ,cholestrol & steroid hormones) 2- Detoxification of toxic substance 3- Muscle contraction (control calcium ions -sarcoplasmic reticulum) 4- Glycogen synthesis

Role of rER in protein synthesis 1- receiving of polypeptide chains in ER lumen 2- storage 3- protein trasport

Golgi apparatus Structure: LM: -Membranous organelle -H&E stain: not apparent - Special stain: silver stain

Golgi apparatus in epididymis (Silver stain) Brown anastomosing network of threads at the secretory border of the cells

EM structure of Golgi apparatus 3 components: - macrovesicles - flattened membranous saccules. (4-10) - microvesicles Flattened membranous cisternae: Convex surface: immature face Concave surface: Secretory face = mature face

Fate of protein transported by rER

Fate of protein transported by rER Primary lysosomes

Functions of Golgi apparatus 1- Chemical modification of proteins 2- Formation of primary lysosomes 3- Secretion of cell products 4- Renewal of the cell membrane

Cytoplasmic Organelles that participate in the process of protein synthesis 1- Ribosomes (factories) 2- Rough endoplasmic reticulum (storage & transport) 3- Golgi apparatus (chemical modification & secretion)

Lysosomes Definition: (Digestive system of the cell) - Membrane bound organelles containing hydrolytic enzymes (Digestive system of the cell)

Lysosomes LM Structure: Histochemical methods staining their enzymes - Membrane bound organelles containing hydrolytic enzymes Structure: LM Histochemical methods staining their enzymes

EM 2 types 1ry lysosome 2ry lysosome small, regular vesicle , contains homogenous dense content 2ry lysosome Large, irregular vesicle, contains heterogenous dense and light contents

Function of lysosomes - The digestive system of the cell (contain hydrolytic enzymes that could digest the food vacuole's contents & destroy old cell organelles)

Formation of the 2 types of lysosomes

Forms of secondary lysosomes 1-pinocytotic vesicles = multivesicular body 2- phagosomes =residual bodies 3- autophagic vacuole = residual bodies 5- Lipofuscin pigment

Mitochondria Structure: LM: -Membranous organelles Mitos= thread chondros= granule -Membranous organelles Structure: LM: -H&E stain: not apparent - Special stain: silver stain

LM picture of mitochondria (special stain: silver stain) mitochondria appear as dark brown granules

EM of the Mitochondria Double membranes: -Outer smooth -Inner folded forming cristae Double spaces: -intermembranous space - intercristal space (matrix space) intermembranous space

- cristae to increase surface area Inner membrane: - cristae to increase surface area - contains protein enzymes for respiratory chain - contains ATP synthetase for ATP synthesis Matrix: - oxidative enzymes - mitochondril DNA so mitochondria can replicate themselves

Function of a mitochondrion -Energy production & storage (ATP synthesis) -Concerned with cell respiration (sites for Kreb’s and fatty acid cycles)

LM: can not be seen EM: - small, rounded - similar to 1ry lysosomes Peroxisomes - Contain 40 oxidative enzymes (urate oxidase) LM: can not be seen EM: - small, rounded - similar to 1ry lysosomes

Functions of peroxisomes: 1- Generate energy but can not store it (NO ATP formation) 2- Maintenance of body temperature (The energy is released as heat). 3- Cell protection : catalase enzyme breaks down H2O2.

Thank you