membranous organelles.pdf

# Practical Histology ## Section 1: Membranous Organelles ### Learning Objectives - Identify histological structure of cell membrane at EM level. - Identify histological structure of rough endoplasmic reticulum at the level. - Identify histological structure of smooth endoplasmic reticulum at t...

# Practical Histology ## Section 1: Membranous Organelles ### Learning Objectives - Identify histological structure of cell membrane at EM level. - Identify histological structure of rough endoplasmic reticulum at the level. - Identify histological structure of smooth endoplasmic reticulum at the level. - Identify histological structure of mitochondria at EM level. ### Components of the cell | Components of the Cell | | |---|---| | 1- Cell membrane | | | 2- Cytoplasm | | **Cell Organelles** | | | A- Membranous | * Mitochondria * Golgi apparatus * Rough endoplasmic reticulum * Smooth endoplasmic reticulum * Lysosomes * Proxisomes * Proteosomes * Annulate lamellae | | B- Non-membranous | * Ribosomes * Centriole * Basal body * Microtubules * Microfilaments * Cilia * Flagella | | 3- Nucleus || | Cell inclusions || | * Storage | | | * Secretor | | | * Excretor | | ### Membranous Organelles - **Nucleus** - **Vacuole** - **Ribosomes** - **Endoplasmic Reticulum** - **Cytoplasm** - **Lysosomes** - **Mitochondria** - **Cell Membrane** - **Golgi Body** ### Cell Membrane - The envelope of the cell. - It encloses its cytoplasmic compartment and its shape. - **L/M:** Appears as a very thin limiting border line. - **E/M:** Tri-lamellar or unit-membrane (7.5-10 nm). - Two thin, dense lines with intervening light area, - Each layer is about 2.5 nm. ### Endoplasmic Reticulum - It is a network of channels present allover the cytoplasm, - Intermittently with the cell and nuclear membranes. - It exists in 2 forms: * **Rough endoplasmic reticulum (rER)** * **Smooth endoplasmic reticulum (sER)** ### Rough Endoplasmic Reticulum (rER) - **Membranous organelle** - **L/M:** Basophilia of the cytoplasm. - **E/M:** Parallel flattened membranous cisternae (tubules & vesicles). - Ribosomes attached to its cytoplasmic surface. - **Function:** Protein synthesis on the ribosomes. ### Smooth Endoplasmic Reticulum (sER) - **Membranous organelle** - **L/M:** Acidophilia of the cytoplasm. - **E/M:** Membranous tubules or vesicles of highly fenestrated cisternae. - No ribosomes (outer smooth surface). - **Function:** Lipid synthesis (cells of adrenal cortex secreting steroids) ### Differences Between Rough and Smooth Endoplasmic Reticulum ### Mitochondria - **E/M:** Elongated, spherical, rounded or filamentous organoid formed of: * **Outer membrane:** Smooth. * **Inner membrane:** Rough (cristae) * Cristae: * Spaces * Inter membrane space: * Inter cristae (matrix) space: * **Mitochondrial matrix** - **Function:** The power houses of the cell ### Group Discussion ### **Identification Of Photomicrographs** 1. **TEM of 2 adjacent Cell membranes** - The photomicrograph shows 2 parallel lines. Each line represents a cell membrane. The middle space between the two dark lines is the intercellular space. 2. **Rough Endoplasmic Reticulum (rER)** - The photomicrograph shows a network of parallel lines or lamellae. Each line represents a membrane of rER. The attached granules in the network represent ribosomes. 3. **Smooth Endoplasmic Reticulum (SER)** - The photomicrograph shows a network of interconnected tubules, vesicles, and cisternae. The network is smooth as it lacks any attached granules. 4. **TEM of Mitochondria** - The photomicrograph shows an oval-shaped organelle with 2 membranes. The internal membrane has folds called cristae. The inner space is the mitochondrial matrix. ### References - Pawlina, W. (2016): A text of Atlas with cell and molecular biology. 7th ed. Lippincott, Williams and Wilkins. - Junqueira, L.C.; Carneiro, J. and Kelly, R.O. (2014): Basic Histology. 11th ed. Appleton and Lange. New York. - Gartner, L.P. and Haiat, J.L. (2011): C.V.S. In: Colour Text Book of Histology, 4th ed. Saunders Elsevier. # Thank you